Agriculture conducted in urban areas is a major contributor to food, fuel and fibre production in the world, and it exists largely for the daily needs of consumers within cities and towns. Urban agriculture uses and reuses natural resources and urban wastes to produce crops and livestock. Table 1 summarizes the variety of farming systems in urban areas. Urban agriculture is a source of income for an estimated 100 million people, and a source of food for 500 million. It is oriented to urban markets rather than national or global markets, and it consists of many small-scale farms and some large-scale agribusinesses. Urban farmers range from a household garden in 20 m² or less, to a small-scale farmer making a living on 200 m², to a large-scale operator who may rent 10 hectares in an industrial zone (UNDP 1996).

Table 1. Farming systems in urban areas

Sources: UNDP 1996; Rowntree 1987.

Landscaping, an offshoot of architecture, has emerged as another urban agriculture endeavour. Landscape gardening is the tending of plants for their ornamental appearance in public parks and gardens, private yards and gardens, and industrial and commercial building plantings. Landscape gardening includes lawn care, planting annuals (bedding plants), and planting and caring for perennials, shrubs and trees. Related to landscape gardening is grounds keeping, in which playing fields, golf courses, municipal parks and so on are tended (Franck and Brownstone 1987).

Process Overview

Urban agriculture is seen as a method for establishing ecological sustainability for towns and cities in the future. Urban agriculture usually engages shorter-cycle, higher-value market crops and uses multi-cropping and integrated farming techniques located where space and water are scarce. It uses both vertical and horizontal space to its best advantage. The principal feature of urban farming is the reuse of waste. The processes are typical of agriculture with similar inputs and steps, but the design is to use both human and animal wastes as fertilizer and water sources for growing vegetation. In this near idealized model, external inputs still exist, however, such as pesticides (UNDP 1996).

In the special case of landscaping, appearance is the product. The care of lawns and ornamental trees, shrubs and flowers are the focus of the landscape operation. In general, the landscaper purchases planting stock from a nursery or a turf farm, plants the stock and cares for it routinely and frequently. It typically is labour and chemical intensive, and the use of hand and power tools and lawn and garden equipment is also common. Grass mowing is a routine chore in landscaping.

Hazards and Their Control

Urban agriculture is typically small scale, close to housing, exposed to urban pollutants, engaged in the reuse of waste and exposed to potential theft of products and related violence. The hazards related to various types of agriculture, pesticides and composting discussed elsewhere in this volume are similar (UNDP 1996).

In the developed countries, suburban farms and landscaping enterprises make use of lawn and garden equipment. This equipment includes small tractors (tractor attachments such as mowers, front-end loaders and blades) and utility haulers (similar to all-terrain vehicles). Other tractor attachments include tillers, carts, snow blowers and trimmers. These tractors all have engines, use fuel, have moving parts, carry an operator and are often used with towed or mounted equipment. They are substantially smaller than the typical agricultural tractor, but they can be overturned and cause serious injury. The fuel used on these tractors poses a fire hazard (Deere & Co. 1994).

Many of the tractor attachments have their own peculiar hazards. Children riding with adults have fallen from the tractor and been crushed under the wheels or chopped by mower blades. Mowers pose two types of hazards: one is potential contact with rotating blades and the other is being struck by objects thrown from the blades. Both front-end loaders and blades are operated hydraulically, and if left unattended and elevated, pose a hazard of falling onto anyone who gets a body part under the attachment. Utility haulers are inexpensive when compared to the cost of a small truck. They can turn over on steep terrain, especially when turning. They are dangerous when used on public roads because of the possibility of collision. (See table 2 for several safety tips for operating some types of lawn and garden equipment.)

Table 2. Safety advice for using mechanical lawn and garden equipment

Tractors (smaller than regular farm equipment)

Prevent rollovers:

• Do not drive where the tractor can tip or slip; avoid steep slopes; watch for rocks, holes
  and similar hazards.

• Travel up and down slopes or hillsides; avoid travelling across steep slopes.

• Slow down and use care in turning to prevent tipping or losing steering and braking control.

• Stay within the tractor load limits; use ballast for stability; refer to the operator’s manual.

Never allow extra riders.

Maintain safety interlocks; they ensure that powered equipment is disengaged
when the operator is not seated or when starting the tractor.

Rotary lawn mowers (tractor mounted or walk-behind type)

Maintain safety interlocks.

Use proper blades and guards.

Keep all safety blades and guards in place and in good condition.

Wear substantial closed-toe shoes to prevent slipping and protect against injury.

Do not allow anyone to put their hands or feet near the mower deck or discharge chute
while the machine is running; stop the mower if children are nearby.

When leaving the machine, shut it down.

To prevent thrown object injuries:

• Clear the area to be mowed.

• Keep the mower deck guards, discharge chute, or bag in place.

• Stop the mower whenever someone comes near.

When working on mower (on push or walk-behind type mowers), disconnect the spark plug
to prevent engine starting.

Avoid fires by not spilling fuel on hot surfaces nor handling fuel near sparks or flames;
avoid the accumulation of fuel, oil and trash around hot surfaces.

Front-end loaders (attached to lawn and garden tractors)

Avoid overloading.

Back down ramps and steep inclines with the loader bucket lowered.

Watch the driving route rather than watching the bucket.

Operate the hydraulic loader controls only from the tractor seat.

Use the loader only for materials that it was designed to handle.

Lower the bucket to the ground when leaving the machine.

Utility haulers (similar to all-terrain vehicles but designed for off-the-road work)

Avoid rollovers:

• Practise driving on smooth terrain before driving on rough terrain.

• Do not speed; slow down before turning (especially on slopes).

• Reduce speed on slopes and rough terrain.

• Watch for holes, rocks and other hidden hazards.

Never allow extra riders.

Avoid tipping over by distributing the cargo box load so it is not too high or too far to rear.

Avoid an upset when raising the cargo box by staying clear of the edge of loading docks
or embankments.

When towing loads, place weight in the cargo box to assure traction.

Avoid driving on public roads.

Children should not operate these machines.

A helmet is recommended head protection.

Source: Adapted from Deere & Co. 1994.

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Migrant and seasonal farmworkers represent a large, global population with the double hazard of occupational health hazards of farming superimposed on a foundation of poverty and migrancy, with its associated health and safety problems. In the United States, for example, there are as many as 5 million migrant and seasonal farmworkers, although precise numbers are not known. As the total farm population has decreased in the United States, the proportion of hired farmworkers has increased. Globally, workers migrate in every region of the world for work, with movement generally from poorer to wealthier countries. In general, migrants are given more hazardous and difficult jobs and have increased rates of illness and injury. Poverty and lack of adequate legal protection exacerbate the risks of occupational and non-occupational disease.

Studies of hazardous exposures and health problems in this population have been limited because of the general paucity of occupational health studies in agriculture and the specific difficulties in studying farmworkers, due to their migratory residence patterns, language and cultural barriers, and limited economic and political resources.

Migrant and seasonal agricultural workers in the United States are predominantly young, Hispanic males, although farmworkers also include whites, blacks, Southeast Asians and other ethnic groups. Almost two-thirds are foreign born; most have low levels of education and do not speak or read English. Poverty is a hallmark of agricultural workers, with over half having family incomes below the poverty level. Substandard working conditions prevail, salaries are low and there are few benefits. For example, less than one-fourth have health insurance. Seasonal and migrant agricultural workers in the United States work about half the year on the farm. Most work is in labour-intensive crops such as harvesting of fruits, nuts or vegetables.

The general health status of agricultural workers directly derives from their working conditions and low income. Deficiencies exist in nutrition, housing, sanitation, education and access to medical care. Crowded living conditions and inadequate nutrition may also contribute to the increased risks of acute, infectious illnesses. Farmworkers see a physician less often than non-farmworking populations, and their visits are overwhelmingly for treatment of acute illnesses and injuries. Preventive care is deficient in farmworker populations, and surveys of farmworker communities find a high prevalence of individuals with medical problems requiring attention. Preventive services such as vision and dental care are seriously deficient, and other preventive services such as immunizations are below the population averages. Anaemia is common, probably reflecting poor nutritional status.

The poverty and other barriers for migrant and seasonal farmworkers generally result in substandard living and working conditions. Many workers still lack access to basic sanitary facilities at the worksite. Living conditions vary from adequate government-maintained housing to substandard shacks and camps used while work exists in a particular area. Poor sanitation and crowding may be particular problems, increasing the risks of infectious diseases in the population. These problems are exacerbated among workers who migrate to follow agricultural work, reducing community resources and interactions at each living site.

Various studies have shown a greater burden of infectious diseases on morbidity and mortality in this population. Parasitic diseases are significantly increased among migrant workers. Increased deaths have been found for tuberculosis, as well as many other chronic diseases such as those of the cardiovascular, respiratory and urinary tracts. The greatest increase in mortality rates is for traumatic injuries, similar to the increase seen for this cause among farmers.

The health status of children of farmworkers is of particular concern. In addition to the stresses of poverty, poor nutrition and poor living conditions, the relative deficiency of preventive health services has a particularly serious impact on children. They also are exposed to the hazards of farming at a young age, both by living in the farming environment and by doing agricultural work. Children under 5 years of age are most at risk of unintentional injury from agricultural hazards such as machinery and farm animals. Above 10 years of age, many children begin working, particularly at times of acute labour need such as during harvesting. Working children may not have the necessary physical strength and coordination for farm labour, nor do they have adequate judgement for many situations. Exposure to agrochemicals is a particular problem, since children may not be aware of recent field application or be able to read warnings on chemical containers.

Farmworkers are at increased risk of pesticide illness during work in the fields. Exposures most commonly occur from direct contact with the spray of application equipment, from prolonged contact with recently sprayed foliage or from drift of pesticide applied by aircraft or other spray equipment. Re-entry intervals exist in some countries to prevent foliar contact while the pesticide on foliage is still toxic, but many places have no re-entry intervals, or they may not be obeyed to hasten the harvest. Mass poisonings from pesticide exposure continue to occur among agricultural workers.

The greatest workplace hazard to farmworkers is from sprains, strains and traumatic injuries. The risk of these outcomes is increased by the repetitive nature of much labour-intensive agricultural work, which often involves workers bending or stooping to reach crops. Some harvesting tasks may require the worker to carry heavy bags full of the harvested commodity, often while balancing on a ladder. There is substantial risk of traumatic injuries and musculoskeletal strains in this situation.

In the United States, one of the most serious causes of fatal injuries to farmworkers is motor vehicle accidents. These often occur when farmworkers are driving or being driven to or from the fields very early or late in the day on unsafe rural roads. Collisions may also occur with slow-moving farm equipment.

Dust and chemical exposures result in an increased risk of respiratory symptoms and disease in farmworkers. The specific hazard will vary with the local conditions and commodities. For example, in dry-climate farming, inorganic dust exposure may result in chronic bronchitis and dust-borne diseases of the lung.

Skin disease is the most common work-related health problem among agricultural workers. There are numerous causes of skin disease in this population, including trauma from using hand equipment such as clippers, irritants and allergens in agrochemicals, allergenic plant and animal materials (including poison ivy and poison oak), nettles and other irritant plants, skin infections caused or exacerbated by heat or prolonged water contact, and sun exposure (which can cause skin cancer).

Many other chronic diseases may be more common among migrant and seasonal farmworkers, but data on actual risks are limited. These include cancer; adverse reproductive outcomes, including miscarriage, infertility and birth defects; and chronic neurologic disorders. All of these outcomes have been observed in other farming populations, or those with high-level exposure to various agricultural toxins, but little is known about actual risk in farmworkers.

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Adapted from 3rd edition, “Encyclopaedia of Occupational Health and Safety”.

The term plantation is widely used to describe large-scale units where industrial methods are applied to certain agricultural enterprises. These enterprises are found primarily in the tropical regions of Asia, Africa and Central and South America, but they are also found in certain subtropical areas where the climate and soil are suitable for the growth of tropical fruits and vegetation.

Plantation agriculture includes short-rotation crops, such as pineapple and sugar cane, as well as tree crops, such as bananas and rubber. In addition, the following tropical and subtropical crops are usually considered as plantation crops: tea, coffee, cocoa, coconuts, mango, sisal and palm nuts. However, large-scale cultivation of certain other crops, such as rice, tobacco, cotton, maize, citrus fruits, castor beans, peanuts, jute, hemp and bamboo, is also referred to as plantation cultivation. Plantation crops have several characteristics:

• They are either tropical or subtropical products for which an export market exists.

• Most require prompt initial processing.

• The crop passes through few local marketing or processing centres before reaching the consumer.

• They typically require a significant investment of fixed capital, such as processing facilities.

• They generate some activity for most of the year, and thus offer continuous employment.

• Monocropping is typical, which allows for specialization of technology and management.

While the cultivation of the various plantation crops requires widely different geographic, geological and climatic conditions, practically all of them thrive best in areas where climatic and environmental conditions are arduous. In addition, the extensive nature of plantation undertakings, and in most cases their isolation, has given rise to new settlements that differ considerably from indigenous settlements (NRC 1993).

Plantation Work

The main activity on a plantation is the cultivation of one of two kinds of crops. This involves the following kinds of work: soil preparation, planting, cultivation, weeding, crop treatment, harvesting, transportation and storage of produce. These operations entail the use of a variety of tools, machines and agricultural chemicals. Where virgin land is to be cultivated, it may be necessary to clear forest land by felling trees, uprooting stumps and burning off undergrowth, followed by ditch and irrigation channel digging. In addition to the basic cultivation work, other activities may also be carried out on a plantation: raising livestock, processing crops and maintaining and repairing buildings, plants, machinery, implements, roads and railway tracks. It may be necessary to generate electricity, dig wells, maintain irrigation trenches, operate engineering or woodworking shops and transport products to the market.

Child labour is employed on plantations around the world. Children work with their parents as part of a team for task-based compensation, or they are employed directly for special plantation jobs. They typically experience long and arduous working hours, little safety and health protection and inadequate diet, rest and education. Rather than direct employment, many children are recruited as labour through contractors, which is common for occasional and seasonal tasks. Employing labour through contracted intermediaries is a long-standing practice on plantations. The plantation management thus does not have an employer- employee relationship with the plantation workers. Rather, they contract with the intermediary to supply the labour. Generally, conditions of work for contract labour are inferior to those of directly employed workers.

Many plantation workers are paid based upon the tasks performed rather than the hours worked. For example, these tasks may include lines of sugar cane cut and loaded, number of rubber trees tapped, rows weeded, bushels of sisal cut, kilograms of tea plucked or hectares of fertilizer applied. Conditions such as climate and terrain may affect the time to complete these tasks, and whole families may work from dawn to dusk without taking a break. The majority of countries where plantation commodities are grown report that plantation employees work more than 40 hours per week. Moreover, most plantation workers move to their work location on foot, and since plantations are large, much time and effort are expended on travel to and from the job. This travel can take hours each way (ILO 1994).

Hazards and Their Prevention

Work on plantations involves numerous hazards relating to the work environment, the tools and equipment used and the very nature of the work. One of the first steps toward improving safety and health on plantations is to appoint a safety officer and form a joint safety and health committee. Safety officers should assure that buildings and equipment are kept safe and that work is performed safely. Safety committees bring management and labour together in a common undertaking and enable the workers to participate directly in improving safety. Safety committee functions include developing work rules for safety, participating in injury and disease investigations and identifying locations that place workers and their families in danger.

Medical services and first aid materials with adequate instruction should be provided. Medical doctors should be trained in the recognition of occupational diseases related to plantation work including pesticide poisoning and heat stress. A risk survey should be implemented on the plantation. The purpose of the survey is to comprehend risk circumstances so that preventive action can be taken. The safety and health committee can be engaged in the survey along with experts including the safety officer, the medical supervisor and inspectors. Table 1  shows the steps involved in a survey. The survey should result in action including the control of potential hazards as well as hazards that have resulted in an injury or disease (Partanen 1996). A description of some potential hazards and their control follow.

Table 1. Ten steps for a plantation work risk survey

1. Define the problem and its priority.
2. Find existing data.
3. Justify the need for more data.
4. Define survey objectives, design, population, time and methods.
5. Define tasks and costs, and their timing.
6. Prepare protocol.
7. Collect data.
8. Analyse data and assess risks.
9. Publish results.
10. Follow up.

Source: Partanen 1996.

Fatigue and climate-related hazards

The long hours and demanding work make fatigue a major concern. Fatigued workers may be unable to make safe judgements; this may lead to incidents that can result in injuries or other inadvertent exposures. Rest periods and shorter workdays can reduce fatigue.

Physical stress is increased by heat and relative humidity. Frequent water consumption and rest breaks help to avoid problems with heat stress.

Tool and equipment-related injuries

Poorly designed tools will often result in poor work posture, and poorly sharpened tools will require greater physical effort to complete tasks. Working in a bent or stooping position and lifting heavy loads imposes strain on the back. Working with arms above the shoulder can cause upper-extremity musculoskeletal disorders (figure 1). Proper tools should be selected to eliminate poor posture, and they should be well maintained. Heavy lifting can be reduced by lessening the weight of the load or engaging more workers to lift the load.

Figure 1. Banana cutters at work on "La Julia" plantation in Ecuador

Injuries can result from improper uses of hand tools such as machetes, scythes, axes and other sharp-edged or pointed tools, or portable power tools such as chain-saws; poor positioning and disrepair of ladders; or unsuitable replacements for broken ropes and chains. Workers should be trained in the proper use and maintenance of equipment and tools. Appropriate replacements should be provided for broken or damaged tools and equipment.

Unguarded machinery can entangle clothing or hair and can crush workers and result in serious injury or death. All machines should have safety built in, and the possibility of dangerous contact with moving parts should be eliminated. A lockout/tagout programme should be in effect for all maintenance and repair.

Machinery and equipment are also sources of excessive noise, resulting in hearing loss among plantation workers. Hearing protection should be used with machinery with high levels of noise. Low noise levels should be a factor in selecting equipment.

Vehicle-related injuries

Plantation roadways and paths may be narrow, thus presenting the hazard of head-on crashes between vehicles or overturns off the side of the road. Safe boarding of transport vehicles including trucks, tractor- or animal-drawn trailers and railways should be ensured. Where two-way roads are used, wider passages should be provided at suitable intervals to allow vehicles to pass. Adequate railing should be provided on bridges and along precipices and ravines.

Tractors and other vehicles pose two principal dangers to workers. One is tractor overturns, which commonly result in the fatal crushing of the operator. Employers should ensure that rollover protective structures are mounted on tractors. Seat-belts should also be worn during tractor operation. The other major problem is vehicle run-overs; workers should remain clear of vehicle travel paths, and extra riders should not be allowed on tractors unless safe seating is available.

Electricity

Electricity is used on plantations in shops and for processing crops and lighting buildings and grounds. Improper use of electric installations or equipment can expose workers to severe shocks, burns or electrocutions. The danger is more acute in damp places or when working with wet hands or clothing. Wherever water is present, or for electrical outlets outdoors, ground fault interrupter circuits should be installed. Wherever thunderstorms are frequent or severe, lightning protection should be provided for all plantation buildings, and workers should be trained in ways to minimize their danger of being struck and to locate safe refuges.

Fires

Electricity as well as open flames or smouldering cigarettes can provide the ignition source for fuel or organic dust explosions. Fuels—kerosene, gasoline or diesel fuel—can cause fires or explosions if mishandled or improperly stored. Greasy and combustible waste poses a risk of fire in shops. Fuels should be kept clear of any ignition source. Flameproof electrical devices and appliances should be used wherever flammables or explosives are present. Fuses or electrical breaker devices should also be used in electrical circuits.

Pesticides

The use of toxic agrochemicals is a major concern, particularly during the intensive use of pesticides, including herbicides, fungicides and insecticides. Exposures can take place during agricultural production, packaging, storage, transport, retailing, application (often by hand or aerial spraying), recycling or disposal. Risk of exposure to pesticides can be aggravated by illiteracy, poor or faulty labelling, leaking containers, poor or no protective gear, dangerous reformulations, ignorance of the hazard, disregard of rules and a lack of supervision or technical training. Workers applying pesticides should be trained in pesticide use and should wear appropriate clothing and respiratory protection, a particularly difficult behaviour to enforce in tropical areas where protective equipment can add to the heat stress of the wearer (figure 2 ). Alternatives to pesticide use should be a priority, or less toxic pesticides should be used.

Figure 2. Protective clothing worn when applying pesticides

Animal-inflicted injuries and illnesses

On some plantations, draught animals are used for dragging or carrying loads. These animals include horses, donkeys, mules and oxen. These types of animals have injured workers by kicking or biting. They also potentially expose workers to zoonotic diseases including anthrax, brucellosis, rabies, Q-fever or tularaemia. Animals should be well trained, and those that exhibit dangerous behaviour should not be used for work. Bridles, harnesses, saddles and so on should be used and maintained in good condition and be properly adjusted. Diseased animals should be identified and treated or disposed of.

Poisonous snakes may be present on the ground or some species may fall from trees onto workers. Snakebite kits should be provided to workers and emergency procedures should be in place for obtaining medical assistance and the appropriate anti-venom drugs should be available. Special hats made of hard materials that are capable of deflecting snakes should be provided and worn in locations where snakes drop on their victims from trees.

Infectious diseases

Infectious diseases can be transmitted to plantation workers by rats that infest buildings, or by drinking water or food. Unsanitary water leads to dysentery, a common problem among plantation workers. Sanitary and washing facilities should be installed and maintained in accordance with national legislation, and safe drinking water consistent with national requirements should be provided to workers and their families.

Confined spaces

Confined spaces, such as silos, can pose problems of toxic gases or oxygen deficiency. Good ventilation of confined spaces should be assured prior to entry, or appropriate respiratory protective equipment should be worn.

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The family farm is an enterprise and a homestead on which both children and the elderly are likely to be present. In some parts of the world, farm families live in villages surrounded by their farm land. The family farm combines family relationships and child raising with the production of food and other raw materials. Family farms range from small, subsistence or part-time operations worked with draught animals and hand tools to very large, family-held corporations with numerous full-time employees. Types of family farms are distinguished by national, regional, cultural, historical, economic, religious and several other factors. The size and type of operations determine the demand for labour from family members and the need for hired full- or part-time workers. A typical farm operation may combine the tasks of livestock handling, manure disposal, grain storage, heavy equipment operation, pesticide application, machinery maintenance, construction and many other jobs.

The Organization for Economic Cooperation and Development (OECD 1994) reports several trends in agriculture, including:

1. the increasing economic dominance of large, highly mechanized producers
2. the increase in off-farm employment as the principal source of income for small farms
3. the controlling role of national and international agricultural policies and trade agreements.

The concentration of farm operations and the reduction in the number of family farms has been recognized for decades. These economic forces affect the work processes, workload and safety and health of the family farm. Several key changes are occurring in family farming as a direct result of these economic forces, including expanding workloads, increasing reliance on hired labor, use of new techniques, unsupervised adolescents and struggling to maintain economic viability.

Children nearing adolescence contribute to family farm productivity. Small and medium-size family farms are likely to rely on this labor, especially when adult family members work off the farm. The result may be unsupervised work by farm children.

Hazards

The family farm is a hazardous work environment. It is one of few hazardous workplaces where multiple generations of family members may live, work and play. A farm can be the source of many and differing life-threatening hazards. The most important indicator for safety and health is workload per worker—both physical labor and decision-making or mental workload. Many serious injuries happen to experienced farmers, working with familiar equipment in familiar fields, while doing tasks that they have been performing for years and even decades.

Hazardous agricultural materials including pesticides, fertilizers, flammable liquids, solvents and other cleaners are responsible for acute and chronic illnesses in farm workers and family members. Tractors, augers and other mechanized equipment have permitted a dramatic increase in the land and livestock that can be worked by a single farmer, but mechanization has contributed to severe injuries in agriculture. Machinery entanglement or tractor rollover, livestock, operating equipment on public roads, falling or being struck by falling objects, material handling, confined spaces and exposures to toxins, dust, moulds, gases, chemicals, vibration and noise are among the principal risks for illness and injury on farms. Climate and topography (e.g., weather, water, slopes, sinkholes and other obstacles) also contribute to the hazards.

Overall, agricultural occupations produce some of the highest rates of death and injury of all types of jobs. Unfortunately, farm children are at great risk along with their parents. As farm families attempt to remain profitable as they expand, family members may take on too high a workload and place themselves at greatly increased risk of fatigue, stress and injury. It is under these conditions that farm children are most likely to try to help out, often working unsupervised. In addition, unrelenting stressors associated with farming may lead to depression, family breakup and suicide. For example, principal owner-operators on single-family farms appear to be at particularly high risk for suicide when compared to other rural residents (Gunderson 1995). Further, the costs of illnesses and injuries are most often borne by the family member(s), and by the family enterprise—both as direct medical costs and in the reduction of labour necessary to maintain the operation.

Prevention

Classic agricultural safety and health programmes emphasize improved engineering design, education and good practices. Special attention on these farms needs to be placed on age-appropriate tasks for children and older adults. Young children should neither be allowed near operating farm equipment nor ever ride on tractors and other farm equipment. They should also be excluded from farmstead buildings that present hazards including electricity, confined spaces, chemical storage areas and operating equipment (National Committee for Childhood Agricultural Injury Prevention 1996). Warning labels should be maintained on equipment and chemicals so adults are informed of hazards and can thus better protect their families. The availability of experienced part-time or full-time workers reduces the burden on the family during periods of high workloads. The abilities of older adults should be a factor in the tasks that they perform.

Self-reliant farmers, determined to complete tasks regardless of the risks, may ignore safe work practices if they perceive them to interfere with farm productivity. Improving safety and health on family farms requires engaging the active participation of farmers and farm workers; improving attitudes, behavioral intentions and work practices; recognizing farm economics and productivity as powerful determinants in shaping the structure and organization of the enterprise; and including agricultural specialists, equipment dealers, insurance agents, bankers, local media, youth and other community members in generating and sustaining a broad climate of farm and community safety.

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Overview

Twelve millennia ago, humankind moved into the Neolithic era and discovered that food, feed and fibre could be produced from the cultivation of plants. This discovery has led to the food and fibre supply that feeds and clothes more than 5 billion people today.

This general profile of the agricultural industry includes its evolution and structure, economic importance of different crop commodities and characteristics of the industry and workforce. Agricultural workforce systems involve three types of major activities:

1. manual operations
2. mechanization
3. draught power, provided specifically by those engaged in livestock rearing, which is discussed in the chapter Livestock rearing.

The agriculture system is shown as four major processes. These processes represent sequential phases in crop production. The agricultural system produces food, feed and fibre as well as consequences for occupational health and, more generally, public health and the environment.

Major commodities, such as wheat or sugar, are outputs from agriculture that are used as food, animal feed or fibre. They are represented in this chapter by a series of articles that address processes, occupational hazards and preventive actions specific to each commodity sector. Animal feed and forage are discussed in the chapter Livestock rearing.

Evolution and Structure of the Industry

The Neolithic revolution—the change from hunting and gathering to farming—started in three different places in the world. One was west and southwest of the Caspian Sea, another was in Central America and a third was in Thailand near the Burmese border. Agriculture started in about 9750 BC at the latter location, where seeds of peas, beans, cucumbers and water chestnuts have been found. This was 2,000 years before true agriculture was discovered in the other two regions. The essence of the Neolithic revolution and, thus, agriculture is the harvesting of plant seeds, their reintroduction into the soil and cultivation for another harvest.

In the lower Caspian area, wheat was the early crop of choice. As farmers migrated, taking wheat seed with them, the weeds in other regions were discovered to also be edible. These included rye and oats. In Central America, where maize and beans were the staples, the tomato weed was found to bear nutritious food.

Agriculture brought with it several problems:

• Weeds and other pests (insects in the fields and mice and rats in the granaries) became a problem.

• Early agriculture concerned itself with taking all that it could from the soil, and it would take 50 years to naturally replenish the soil.

• In some places, the stripping of growth from the soil would turn the land to desert. To provide water to crops, farmers discovered irrigation about 7,000 years ago.

Solutions to these problems have led to new industries. Ways to control weeds, insects and rodents evolved into the pesticide industry, and the need to replenish the soil has resulted in the fertilizer industry. The need to provide water for irrigation has spawned systems of reservoirs and networks of pipes, canals and ditches.

Agriculture in the developing nations consists principally of family-owned plots. Many of these plots have been handed down from generation to generation. Peasants make up half of the world’s rural poor, but they produce four-fifths of the developing countries’ food supply. In contrast, farms are increasing in size in the developed countries, turning agriculture into large-scale commercial operations, where production is integrated with processing, marketing and distribution in an agribusiness system (Loftas 1995).

Agriculture has provided subsistence for farmers and their families for centuries, and it has recently changed into a system of production agriculture. A series of “revolutions” has contributed to an increase in agricultural production. The first of these was the mechanization of agriculture, whereby machines in the fields substituted for manual labour. The second was the chemical revolution that, after the Second World War, contributed to the control of pests in agriculture, but with environmental consequences. A third was the green revolution, which contributed to North American and Asian productivity growth through genetic advances in the new varieties of crops.

Economic Importance

The human population has grown from 2.5 billion in 1950 to 5.6 billion in 1994, and the United Nations estimates that it will continue to grow to 7.9 billion by 2025. The continued rise in the human population will increase the demand for food energy and nutrients, both because of the increase in numbers of people and the global drive to combat malnutrition (Brown, Lenssen and Kane 1995). A list of nutrients derived from food is shown in table 1.

Table 1. Sources of nutrients

Source: Loftas 1995.

Agriculture today can be understood as an enterprise to provide subsistence for those doing the work, staples for the community in which the food is grown and income from the sale of commodities to an external market. A staple food is one that supplies a major part of energy and nutrient needs and constitutes a dominant part of the diet. Excluding animal products, most people live off of one or two of the following staples: rice, wheat, maize (corn), millet, sorghum, and roots and tubers (potatoes, cassava, yams and taro). Although there are 50,000 edible plant species in the world, only 15 provide 90% of the world’s food energy intake.

Cereals constitute the principal commodity category that the world depends upon for its staples. Cereals include wheat and rice, the principal food staples, and coarse grains, which are used for animal feed. Three—rice, maize and wheat—are staples to more than 4.0 billion people. Rice feeds about half of the world’s population (Loftas 1995).

Another basic food crop is the starchy foods: cassava, sweet potatoes, potatoes, yams, taro and plantains. More than 1 billion people in developing nations use roots and tubers as staples. Cassava is grown as a staple in developing countries for 500 million people. For some of these commodities, much of the production and consumption remains at the subsistence level.

An additional basic food crop is the pulses, which comprise a number of dry beans—peas, chickpeas and lentils; all are legumes. They are important for their starch and protein.

Other legumes are used as oil crops; they include soybeans and groundnuts. Additional oil crops, used to make vegetable oil, include coconuts, sesame, cotton seed, oil palm and olive. In addition, some maize and rice bran are used to make vegetable oil. Oil crops also have uses other than for food, such as in manufacturing paints and detergents (Alexandratos 1995).

Small landholders grow many of the same crops as plantation operations do. Plantation crops, typically thought of as tropical export commodities, include natural rubber, palm oil, cane sugar, tropical beverages (coffee, cocoa, tea), cotton, tobacco and bananas. They may include crops that are also grown for both local consumption and export, such as coffee and sugar cane (ILO 1994).

Urban agriculture is labour intensive, occurs on small plots and is present in developed as well as developing countries. In the United States, more than one-third of the dollar value of agricultural crops is produced in urban areas and agriculture may employ as much as 10% of the urban population. In contrast, up to 80% of the population in smaller Siberian and Asian cities may be employed in agricultural production and processing. An urban farmer’s produce may also be used for barter, such as paying a landlord (UNDP 1996).

Characteristics of the Industry and Workforce

The 1994 world population totalled 5,623,500,000, and 2,735,021,000 (49%) of this population was engaged in agriculture, as shown in figure 1 . The largest component of this workforce is in the developing nations and transitional economies. Less than 100 million are in the developed nations, where mechanization has added to their productivity.

Figure 1. Millions of people engaged in agriculture by world region (1994)

Farming employs men and women, young and old. Their roles vary; for example, women in sub-Saharan Africa produce and market 90% of locally grown food. Women are also given the task of growing the subsistence diet for their families (Loftas 1995).

Children become farm labourers around the world at an early age (figure 2 ), working typically 45 hours per week during harvesting operations. Child labour has been a part of plantation agriculture throughout its history, and a prevalent use of contract labour based upon compensation for tasks completed aggravates the problem of child labour. Whole families work to increase the task completion in order to sustain or increase their income.

Figure 2. Young boy working in agriculture in India

Data on plantation employment generally show that the highest incidence of poverty is among agricultural wage labourers working in commercial agriculture. Plantations are located in tropical and subtropical regions of the world, and living and working conditions there may aggravate health problems that accompany the poverty (ILO 1994).

Agriculture in urban areas is another important component of the industry. An estimated 200 million farmers work part-time—equivalent to 150 million full-time workers—in urban agriculture to produce food and other agricultural products for the market. When subsistence agriculture in urban areas is included, the total reaches 800 million (UNDP 1996).

Total agricultural employment by major world region is shown in figure 1. In both the United States and Canada, a small proportion of the population is employed in agriculture, and farms are becoming fewer as operations consolidate. In Western Europe, agriculture has been characterized by smallholdings, a relic of equal division of the previous holding among the children. However, with the migration from agriculture, holdings in Europe have been increasing in size. Eastern Europe’s agriculture carries a history of socialized farming. The average farm size in the former USSR was more than 10,000 hectares, while in other Eastern European countries it was about one-third that size. This is changing as these countries move toward market economies. Many Asian countries have been modernizing their agricultural operations, with some countries achieving rice surpluses. More than 2 billion people remain engaged in agriculture in this region, and much of the increased production is attributed to high- production species of crops such as rice. Latin America is a diverse region where agriculture plays an important economic role. It has vast resources for agricultural use, which has been increasing, but at the expense of tropical forests. In both the Middle East and Africa, per capita food production has seen a decline. In the Middle East, the principal limiting factor on agriculture is the availability of water. In Africa, traditional farming depends upon small, 3- to 5-hectare plots, which are operated by women while the men are employed elsewhere, some in other countries to earn cash. Some countries are developing larger farming operations.

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Characteristic Chemical Pollutants

Chemical contaminants of the indoor air can occur as gases and vapors (inorganic and organic) and particulates. Their presence in the indoor environment is the result of entry into the building from the outdoor environment or their generation within the building. The relative importance of these indoor and outdoor origins differs for different pollutants and may vary over time.

The major chemical pollutants commonly found in the indoor air are the following:

1. carbon dioxide (CO₂), which is a metabolic product and often used as an indicator of the general level of air pollution related to the presence of humans indoors
2. carbon monoxide (CO), nitrogen oxides (NO_x) and sulphur dioxide (SO₂), which are inorganic combustion gases formed predominantly during the combustion of fuels and ozone (O₃), which is a product of photochemical reactions in polluted atmospheres but may also be released by some indoor sources
3. organic compounds that originate from a variety of indoor sources and outdoors. Hundreds of organic chemicals occur in indoor air although most are present at very low concentrations. These can be grouped according to their boiling points and one widely used classification, shown in Table 1, identifies four groups of organic compounds: (1) very volatile organic compounds (VVOC); (2) volatile (VOC); (3) semi-volatile (SVOC); and (4) organic compounds associated with particulate matter (POM). Particle-phase organics are dissolved in or adsorbed on particulate matter. They may occur in both the vapor and particle phase depending on their volatility. For example, polyaromatic hydrocarbons (PAHs) consisting of two fused benzene rings (e.g., naphthalene) are found principally in the vapor phase and those consisting of five rings (e.g., benz[a]pyrene) are found predominantly in the particle phase.

Table 1. Classification of indoor organic pollutants

An important characteristic of indoor air contaminants is that their concentrations vary both spatially and temporally to a greater extent than is common outdoors. This is due to the large variety of sources, the intermittent operation of some of the sources and the various sinks present.

Concentrations of contaminants that arise principally from combustion sources are subject to very large temporal variation and are intermittent. Episodic releases of volatile organic compounds due to human activities such as painting also lead to large variations in emission with time. Other emissions, such as formaldehyde release from wood-based products may vary with temperature and humidity fluctuations in the building, but the emission is continuous. The emission of organic chemicals from other materials may be less dependent upon temperature and humidity conditions but their concentrations in indoor air will be greatly influenced by ventilation conditions.

Spatial variations within a room tend to be less pronounced than temporal variations. Within a building there may be large differences in the case of localized sources, for example, photocopiers in a central office, gas cookers in the restaurant kitchen and tobacco smoking restricted to a designated area.

Sources within the Building

Elevated levels of pollutants generated by combustion, particularly nitrogen dioxide and carbon monoxide in indoor spaces, usually result from unvented, improperly vented or poorly maintained combustion appliances and the smoking of tobacco products. Unvented kerosene and gas space heaters emit significant quantities of CO, CO₂, NO_x, SO₂, particulates and formaldehyde. Gas cooking stoves and ovens also release these products directly into the indoor air. Under normal operating conditions, vented gas-fired forced air heaters and water heaters should not release combustion products into the indoor air. However flue gas spillage and backdrafting can occur with faulty appliances when the room is depressurized by competing exhaust systems and under certain meteorological conditions.

Environmental tobacco smoke

Indoor air contamination from tobacco smoke results from sidestream and exhaled mainstream smoke, usually referred to as environmental tobacco smoke (ETS). Several thousand different constituents have been identified in tobacco smoke and the total quantities of individual components varies depending upon the type of cigarette and the conditions of smoke generation. The main chemicals associated with ETS are nicotine, nitrosamines, PAHs, CO, CO₂, NO_x, acrolein, formaldehyde and hydrogen cyanide.

Building materials and furnishings

The materials which have received greatest attention as sources of indoor air pollution have been wood-based boards containing urea formaldehyde (UF) resin and UF cavity wall insulation (UFFI). Emission of formaldehyde from these products results in elevated levels of formaldehyde in buildings and this has been associated with many complaints of poor indoor air quality in developed countries, particularly during the late 1970s and early 1980s. Table 2 gives examples of materials that release formaldehyde in buildings. These show that the highest emission rates may be associated with the wood-based products and UFFI which are products often used extensively in buildings. Particleboard is manufactured from fine (about 1 mm) wood particles which are mixed with UF resins (6 to 8 weight%) and pressed into wood panels. It is widely used for flooring, wall panelling, shelving and components of cabinets and furniture. The plies of hardwood are bonded with UF resin and are commonly used for decorative wall panelling and components of furniture. Medium-density fibreboard (MDF) contains finer wood particles than those used in particleboard and these are also bound with UF resin. MDF is most often used for furniture. The primary source of formaldehyde in all these products is the residual formaldehyde trapped in the resin as a result of its presence in excess needed for the reaction with urea during the manufacture of the resin. Release is therefore highest when the product is new, and declines at a rate dependent upon product thickness, initial emission strength, presence of other formaldehyde sources, local climate and occupant behaviour. The initial decline rate of emissions may be 50% over the first eight to nine months, followed by a much slower rate of decline. Secondary emission can occur due to hydrolysis of the UF resin and hence emission rates increase during periods of elevated temperature and humidity. Considerable efforts by manufacturers have led to the development of lower-emitting materials by use of lower ratios (i.e. closer to 1:1) of urea to formaldehyde for resin production and the use of formaldehyde scavengers. Regulation and consumer demand have resulted in widespread use of these products in some countries.

Table 2. Formaldehyde emission rates from a variety of construction material furnishings and consumer products

Building materials and furnishings release a wide range of other VOCs which have been the subject of increasing concern during the 1980s and 1990s. The emission can be a complex mixture of individual compounds, though a few may be dominant. A study of 42 building materials identified 62 different chemical species. These VOCs were primarily aliphatic and aromatic hydrocarbons, their oxygen derivatives and terpenes. The compounds with the highest steady-state emission concentrations, in decreasing order, were toluene, m-xylene, terpene, n-butylacetate, n-butanol, n-hexane, p-xylene, ethoxyethylacetate, n-heptane and o-xylene. The complexity of emission has resulted in emissions and concentrations in air often being reported as the total volatile organic compound (TVOC) concentration or release. Table 3 gives examples of rates of TVOC emission for a range of building products. These show that significant differences in emissions exist between products, which means that if adequate data were available materials could be selected at the planning stage to minimize the VOC release in newly constructed buildings.

Table 3. Total volatile organic compound (TVOC) concentrations and emission rates associated with various floor and wall coverings and coatings

^a PVC, polyvinyl chloride.

Wood preservatives have been shown to be a source of pentachlorophenol and lindane in the air and in dust within buildings. They are used primarily for timber protection for outdoor exposure and are also used in biocides applied for treatment of dry rot and insect control.

Consumer products and other indoor sources

The variety and number of consumer and household products change constantly, and their chemical emissions depend on use patterns. Products that may contribute to indoor VOC levels include aerosol products, personal hygiene products, solvents, adhesives and paints. Table 4 illustrates major chemical components in a range of consumer products.

Table 4. Components and emissions from consumer products and other sources of volatile organic compounds (VOC)

Other VOCs have been associated with other sources. Chloroform is introduced into the indoor air chiefly as a result of dispensing or heating tap water. Liquid process copiers release isodecanes into the air. Insecticides used to control cockroaches, termites, fleas, flies, ants and mites are widely used as sprays, fogging devices, powders, impregnated strips, bait and pet collars. Compounds include diazinon, paradichlorobenzene, pentachlorophenol, chlordane, malathion, naphthalene and aldrin.

Other sources include occupants (carbon dioxide and odours), office equipment (VOCs and ozone), mould growth (VOCs, ammonia, carbon dioxide), contaminated land (methane, VOCs) and electronic air cleaners and negative ion generators (ozone).

Contribution from the external environment

Table 5 shows typical indoor-outdoor ratios for the major types of pollutant that occur in indoor air and average concentrations measured in outdoor air of urban areas in the United Kingdom. Sulphur dioxide in the indoor air is normally of outdoor origin and results from both natural and anthropogenic sources. Combustion of fossil fuels containing sulphur and smelting of sulphide ores are major sources of sulphur dioxide in the troposphere. Background levels are very low (1 ppb) but in urban areas maximum hourly concentrations may be 0.1 to 0.5 ppm. Sulphur dioxide can enter a building in air used for ventilation and can infiltrate through small gaps in the building structure. This depends upon the airtightness of the building, meteorological conditions and internal temperatures. Once inside, the incoming air will mix and be diluted by the indoor air. Sulphur dioxide that comes into contact with building and furnishing materials is adsorbed and this can significantly reduce the indoor concentration with respect to the outdoors, particularly when outdoor sulphur dioxide levels are high.

Table 5. Major types of chemical indoor air contaminant and their concentrations in the urban United Kingdom

^a ETS, environmental tobacco smoke.

Nitrogen oxides are a product of combustion, and major sources include automobile exhaust, fossil fuel-fired electric generating stations and home space heaters. Nitric oxide (NO) is relatively non-toxic but can be oxidized to nitrogen dioxide (NO₂), particularly during episodes of photochemical pollution. Background concentrations of nitrogen dioxide are about 1 ppb but may reach 0.5 ppm in urban areas. The outdoors is the major source of nitrogen dioxide in buildings without unvented fuel appliances. As with sulphur dioxide, adsorption by internal surfaces reduces the concentration indoors compared with that outdoors.

Ozone is produced in the troposphere by photochemical reactions in polluted atmospheres, and its generation is a function of intensity of sunlight and concentration of nitrogen oxides, reactive hydrocarbons and carbon monoxide. At remote sites, background ozone concentrations are 10 to 20 ppb and can exceed 120 ppb in urban areas in summer months. Indoor concentrations are significantly lower due to reaction with indoor surfaces and the lack of strong sources.

Carbon monoxide release as a result of anthropogenic activities is estimated to account for 30% of that present in the atmosphere of the northern hemisphere. Background levels are approximately 0.19 ppm and in urban areas a diurnal pattern of concentrations is related to use of the motor vehicle with peak hourly levels ranging from 3 ppm to 50 to 60 ppm. It is a relatively unreactive substance and so is not depleted by reaction or adsorption on indoor surfaces. Indoor sources such as unvented fuel appliances therefore add to the background level otherwise due to the outdoor air.

The indoor-outdoor relationship of organic compounds is compound-specific and may vary over time. For compounds with strong indoor sources such as formaldehyde, indoor concentrations are usually dominant. For formaldehyde outdoor concentrations are typically below 0.005 mg/m³ and indoor concentrations are ten times higher than outdoor values. Other compounds such as benzene have strong outdoor sources, petrol-driven vehicles being of particular importance. Indoor sources of benzene include ETS and these result in mean concentrations in buildings in the United Kingdom being 1.3 times higher than those outdoors. The indoor environment appears not to be a significant sink for this compound and it is therefore not protective against benzene from outdoors.

Typical Concentrations in Buildings

Carbon monoxide concentrations in indoor environments commonly range from 1 to 5 ppm. Table 6 summarizes results reported in 25 studies. Concentrations are higher in the presence of environmental tobacco smoke, though it is exceptional for concentrations to exceed 15 ppm.

Table 6. Summary of field measurements of nitrogen oxides (NO^x) and carbon monoxide (CO)

^a ND = not detected.

Nitrogen dioxide concentrations indoors are typically 29 to 46 ppb. If particular sources such as gas stoves are present, concentrations may be significantly higher, and smoking can have a measurable effect (see table 6).

Many VOCs are present in the indoor environment at concentrations ranging from approximately 2 to 20 mg/m³. A US database containing 52,000 records on 71 chemicals in homes, public buildings and offices is summarized in Figure 3. Environments where heavy smoking and/or poor ventilation create high concentrations of ETS can produce VOC concentrations of 50 to 200 mg/m³. Building materials make a significant contribution to indoor concentrations and new homes are likely to have a greater number of compounds exceeding 100 mg/m³. Renovation and painting contribute to significantly higher VOC levels. Concentrations of compounds such as ethyl acetate, 1,1,1-trichloroethane and limonene can exceed 20 mg/m³ during occupant activities, and during residents’ absence the concentration of a range of VOCs may decrease by about 50%. Specific cases of elevated concentrations of contaminants due to materials and furnishings being associated with occupant complaints have been described. These include white spirit from injected damp-proof courses, naphthalene from products containing coal tar, ethylhexanol from vinyl flooring and formaldehyde from wood-based products.

Figure 1. Daily indoor concentrations of selected compounds for indoor sites.

The large number of individual VOCs occurring in buildings makes it difficult to detail concentrations for more than selected compounds. The concept of TVOC has been used as a measure of the mixture of compounds present. There is no widely used definition as to the range of compounds that the TVOC represents, but some investigators have proposed that limiting concentrations to below 300 mg/m³ should minimize complaints by occupants about indoor air quality.

Pesticides used indoors are of relatively low volatility and concentrations occur in the low microgram-per-cubic-meter range. The volatilized compounds can contaminate dust and all indoor surfaces because of their low vapor pressures and tendency to be adsorbed by indoor materials. PAH concentrations in air are also strongly influenced by their distribution between the gas and aerosol phases. Smoking by occupants can have a strong effect on indoor air concentrations. Concentrations of PAHs range typically range from 0.1 to 99 ng/m³.

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All new buildings and civil engineering structures go through the same cycle of conception or design, groundworks, building or erection (including the roof of a building), finishing and provision of utilities and final commissioning before being brought into use. In the course of years, those once new buildings or structures require maintenance including re-painting and cleaning; they are likely to be renovated by being updated or changed or repaired to correct damage by weather or accident; and finally they will need to be demolished to make way for a more modern facility or because their use is no longer required. This is true of houses; it is also true of large, complex structures like power stations and bridges. Each stage in the life of a building or civil engineering structure presents hazards, some of which are common to all work in construction (like the risk from falls) or unique to the particular type of project (such as the risk from collapse of excavations during preparation of foundations in either building or civil engineering).

For each type of project (and, indeed, each stage within a project) it is possible to forecast what will be the principal hazards to the safety of construction workers. The risk from falls is common to all construction projects, even those at ground level. This is supported by the evidence of accident data which show that up to half of fatal accidents to construction workers involve falls.

New Facilities

Conception (design)

Physical hazards to those engaged in design of new facilities normally arise from visits by professional staff to carry out surveys. Visits by unaccompanied staff to unknown or abandoned sites may expose them to risks from dangerous access, unguarded openings and excavations and, in a building, to electrical wiring and equipment in a dangerous condition. If the survey requires entry into rooms or excavations that have been closed for some time, there is the risk of being overcome by carbon dioxide or reduced oxygen levels. All hazards are increased if visits are made to an unlit site after dark or if the lone visitor has no means of communicating with others and summoning aid. As a general rule, professional staff should not be required to visit sites where they will be on their own. They should not visit after dark unless the site is well lit. They should not enter enclosed spaces unless these have been tested and shown to be safe. Lastly, they should be in communication with their base or have an effective means of getting help.

Conception or design proper should play an important part in influencing safety when contractors are actually working onsite. Designers, be they architects or civil engineers, should be expected to be more than mere producers of drawings. In creating their design, they should, by reason of their training and experience, have some idea how contractors are likely to have to work in putting the design into effect. Their competence should be such that they are able to identify to contractors the hazards that will arise from those methods of working. Designers should try to “design out” hazards arising from their design, making the structure more “buildable” as regards health and safety and, where possible, substituting safer materials in the specifications. They should improve access for maintenance at the design stage and reduce the need for maintenance workers to be put at risk by incorporating features or materials that will require less frequent attention during the life of the building.

In general, designers are able to design out hazards only to a limited extent; there will usually be significant residual risks that the contractors will have to take into account when devising their own safe systems of work. Designers should provide contractors with information on these hazards so that the latter are able to take both the hazards and necessary safety procedures into account, firstly when tendering for the job, and secondly when developing their systems of work to do the job safely.

The importance of specifying materials with better health and safety properties tends to be underestimated when considering safety by design. Designers and specifiers should consider whether materials are available with better toxic or structural properties or that can be used or maintained more safely. This requires designers to think about the materials that will be used and to decide whether following previous practice will adequately protect construction workers. Often cost is the determining factor in choice of materials. However, clients and designers should realize that while materials with better toxic or structural properties may have a higher initial cost, they often yield much bigger savings over the life of the building because construction and maintenance workers require less expensive access or protective equipment.

Excavation

Usually the first job to be done on the site after site surveys and laying out of the site once the contract has been awarded (assuming there is no need for demolition or site clearance) is groundworks for the foundations. In the case of domestic housing, the footings are unlikely to require excavations greater than half a metre and may be dug by hand. For blocks of flats, commercial and industrial buildings and some civil engineering, the foundations may need to be several metres below ground level. This will require the digging of trenches in which work will have to carried out to lay or erect the foundations. Trenches deeper than 1 m are likely to be dug using machines such as excavators. Excavations are also dug to permit laying of cables and pipes. Contractors often use special-purpose excavators capable of digging deep but narrow excavations. If workers have to enter these excavations, the hazards are essentially the same as those encountered in excavations for foundations. However, there is usually more scope in cable and pipe excavations or trenches to adopt methods of working that do not require workers to enter the excavation.

Work in excavations deeper then 1 m needs especially careful planning and supervision. The hazard is the risk of being struck by earth and debris as the ground collapses along the side of the excavation. Ground is notoriously unpredictable; what looks firm can be caused to slip by rain, frost or vibration from other construction activities nearby. What looks like firm, stiff clay dries out and cracks when exposed to the air or will soften and slip after rain. A cubic metre of earth weighs more than 1 tonne; a worker struck by only a small fall of ground risks broken limbs, crushed internal organs and suffocation. Because of the vital importance to safety of selecting a suitable method of support for the sides of the excavation, before work starts, the ground should be surveyed by a person experienced in safe excavation work to establish the type and condition of the ground, especially the presence of water.

Support for trench sides

Double-sided support. It is not safe to rely on cutting or “battering” back the sides of the excavation to a safe angle. If the ground is wet sand or silt, the safe angle of batter would be as low as 5 to 10 above horizontal, and there is generally not enough room onsite for such a wide excavation. The most common method of providing safety for work in excavations is to support both sides of the trench through shoring. With double-sided support, the loads from the ground on one side are resisted by similar loads acting through struts between the opposing sides. Timber of good quality must be used to provide vertical elements of the support system, known as poling boards. Poling boards are driven into the ground as soon as excavation begins; the boards are edge to edge, and thus provide a timber wall. This is done on each side of the excavation. As the excavation is dug deeper, the poling boards are driven into the ground ahead of the excavation. When the excavation is a metre deep, a row of horizontal boards (known as walings or wales) is placed against the poling boards and then held in position by timber or metal struts wedged between the opposing walings at regular intervals. As digging proceeds, the poling boards are driven further into the ground with their walings and struts, and it will be necessary to create a second row of walings and struts if the excavation is deeper than 1.2 m. Indeed, an excavation of 6 m could require up to four rows of walings.

The standard timber methods of support are unsuitable if the excavation is deeper than 6 m or the ground is water bearing. In these situations, other types of support for the sides of excavations are required, such as vertical steel trench sheets, closely spaced with horizontal timber walings and metal adjustable struts, or full-scale steel sheet piling. Both methods have the advantage that the trench sheets or sheet piles can be driven by machine before excavation proper starts. Also, trench sheets and sheet piles can be withdrawn at the end of the job and re-used. Support systems for excavations deeper than 6 m or in water-bearing ground should be custom designed; standard solutions will not be adequate.

Single-sided support. An excavation that is rectangular in shape and too large for the support methods described above to be practicable may have one or more of its sides supported by a row of poling boards or trench sheets. These are themselves supported first by one or more rows of horizontal walings which are themselves then held in place by angled rakes back to a strong anchorage or support point.

Other systems. It is possible to use manufactured steel boxes of adjustable width that may be lowered into excavations and within which work can be carried out safely. It is also possible to use proprietary waling frame systems, whereby a horizontal frame is lowered into the excavation between the poling boards or trench sheets; the waling frame is forced apart and applies pressure to keep the poling boards upright by the action of hydraulic struts across the frame which can be pumped from a position of safety outside the excavation.

Training and supervision. Whatever method of support is adopted, the work should be carried out by trained workers under supervision of an experienced person. The excavation and its supports should be inspected each day and after each occasion that they have been damaged or displaced (e.g., after a heavy rain). The only assumption one is entitled to make regarding safety and work in excavations is that all ground is liable to fail and therefore no work should ever be carried out with workers in an unsupported excavation deeper than 1 m. See also the article “Trenching” in this chapter.

Superstructure

Erection of the main part of the building or civil engineering structure (the superstructure) takes place after completion of the foundation. This part of the project usually requires work at heights above ground. The biggest single cause of fatal and major injury accidents is falls from heights or on the same level.

Ladder work

Even if the job is simply building a house, the number of workers involved, the amount of building materials to be handled and, in later stages, the heights at which work will have to be carried out all require more than simple ladders for access and safe places of work.

There are limitations on the sort of work that can be done safely from ladders. Work more than 10 m above ground is usually beyond the safe reach of ladders; lengthy ladders themselves become dangerous to handle. There are limitations on the reach of workers on ladders as well as on the amount of equipment and materials they can safely carry; the physical strain of standing on ladder rungs limits the time they can spend on such work. Ladders are useful for carrying out short-duration, light-weight work within safe reach of the ladder; typically, inspection and repair and painting of small areas of the building’s surface. Ladders also provide access in scaffolds, in excavations and in structures where more permanent access has not yet been provided.

It will be necessary to use temporary working platforms, the most common of which is scaffolding. If the job is a multi-storey block of flats, office building or structure like a bridge, then scaffolding of varying degrees of complexity will be required, depending on the scale of the job.

Scaffolds

Scaffolds consist of easily assembled frameworks of steel or timber on which working platforms may be placed. Scaffolds may be fixed or mobile. Fixed scaffolds—that is, those erected alongside a building or structure—are either independent or putlog. The independent scaffold has uprights or standards along both sides of its platforms and is capable of remaining upright without support from the building. The putlog scaffold has standards along the outer edges of its working platforms, but the inner side is supported by the building itself, with parts of the scaffold frame, the putlogs, having flattened ends that are placed between courses of brickwork to gain support. Even the independent scaffold needs to be rigidly “tied” or secured to the structure at regular intervals if there are working platforms above 6 m or if the scaffold is sheeted for weather protection, thus increasing wind-loadings.

Working platforms on scaffolds consist of good-quality timber boards laid so that they are level and both ends are properly supported; intervening supports will be necessary if the timber is liable to sag due to loading by people or materials. Platforms should never be less than 600 mm in width if used for access and working or 800 mm if used also for materials. Where there is a risk of falling more than 2 m, the outer edge and ends of a working platform should be protected by a rigid guard rail, secured to the standards at a height of between 0.91 and 1.15 m above the platform. To prevent materials falling off the platform, a toe board rising at least 150 mm above the platform should be provided along its outer edge, again secured to the standards. If guard rails and toe-boards have to be removed to permit passage of materials, they should be replaced as soon as possible.

Scaffold standards should be upright and properly supported at their bases on base plates, and if necessary on timber. Access within fixed scaffolds from one working platform level to another is usually by means of ladders. These should be properly maintained, secured at top and bottom and extend at least 1.05 m above the platform.

The principal hazards in the use of scaffolds—falls of person or materials—usually arise from shortcomings either in the way the scaffold is first erected (e.g., a piece such as a guard rail is missing) or in the way it is misused (e.g., by being overloaded) or adapted during the course of the job for some purpose that is unsuitable (e.g., sheeting for weather protection is added without adequate ties to the building). Timber boards for scaffold platforms become displaced or break; ladders are not secured at top and bottom. The list of things that can go wrong if scaffolds are not erected by experienced persons under proper supervision is almost limitless. Scaffolders are themselves particularly at risk from falls during erection and dismantling of scaffolds, because they are often obliged to work at heights, in exposed positions without proper working platforms (see figure 1).

Figure 1.  Assembling scaffolding at a Geneva, Switzerland, construction site without adequate protection. 

Tower scaffolds. Tower scaffolds are either fixed or mobile, with a working platform on top and an access ladder inside the tower frame. The mobile tower scaffold is on wheels. Such towers easily become unstable and should be subject to height limitations; for the fixed tower scaffold the height should not be more than 3.5 times the shortest base dimension; for mobile, the ratio is reduced to 3 times. The stability of tower scaffolds should be increased by use of outriggers. Workers should not be permitted on the top of mobile tower scaffolds while the scaffold is being moved or without the wheels being locked.

The principal hazard with tower scaffolds is overturning, throwing people off the platform; this may be due to the tower being too tall for its base, failure to use outriggers or lock wheels or unsuitable use of the scaffold, perhaps by overloading it.

Slung and suspended scaffolds. The other main category of scaffold is those that are slung or suspended. The slung scaffold is essentially a working platform hung by wire ropes or scaffold tubes from an overhead structure like a bridge. The suspended scaffold is again a working platform or cradle, suspended by wire ropes, but in this case it is capable of being raised and lowered. It is often provided for maintenance and painting contractors, sometimes as part of the equipment of the finished building.

In either case, the building or structure must be capable of supporting the slung or suspended platform, the suspension arrangements must be strong enough and the platform itself should be sufficiently robust to carry the intended load of people and materials with guard sides or rails to prevent them from falling out. For the suspended platform, there should be at least three turns of rope on the winch drums at the lowest position of the platform. Where there are no arrangements to prevent the suspended platform from falling in the event of failure of a rope, workers using the platform should wear a safety harness and rope attached to a secure anchorage point on the building. Persons using such platforms should be trained and experienced in their use.

The principal hazard with slung or suspended scaffolds is failure of the supporting arrangements, either of the structure itself or the ropes or tubes from which the platform is hung. This can arise from incorrect erection or installation of the slung or suspended scaffold or from overloading or other misuse. Failure of suspended scaffolds has resulted in multiple fatalities and can endanger the public.

All scaffolds and ladders should be inspected by a competent person at least weekly and before being used again after weather conditions that may have damaged them. Ladders which have cracked styles or broken rungs should not be used. Scaffolders who erect and dismantle scaffolds should be given specific training and experience to ensure their own safety and the safety of others who may use the scaffolds. Scaffolds are often provided by one, perhaps the main, contractor for use by all contractors. In this situation, tradespeople may modify or displace parts of scaffolds to make their own job easier, without restoring the scaffold afterwards or realizing the hazard they have created. It is important that the arrangements for coordination of health and safety across the site deal effectively with the action of one trade on the safety of another.

Powered access equipment

On some jobs, during both construction and maintenance, it may be more practicable to use powered access equipment than scaffolding in its various forms. Providing access to the underside of a factory roof undergoing recladding or access to the outside of a few windows in a building may be safer and cheaper than scaffolding out the whole structure. Powered access equipment comes in a variety of forms from manufacturers, for example, platforms that may be raised and lowered vertically by hydraulic action or the opening and closing of scissor jacks and hydraulically-powered articulated arms with a working platform or cage on the end of the arm, commonly called cherry pickers. Such equipment is generally mobile and can be moved to the place it is required and brought into use in a matter of moments. Safe use of powered access equipment requires that the job be within the specification for the machine as described by the manufacturer (i.e., the equipment must not overreach or be overloaded).

Powered access equipment requires a firm, level floor on which to operate; it may be necessary to put out outriggers to ensure that the machine does not tip over. Workers on the working platform should have access to operating controls. Workers should be trained in safe use of such equipment. Properly operated and maintained, powered access equipment can provide safe access where it may be virtually impossible to provide scaffolding, for example, during the early stages of erection of a steel frame or to provide access for steel erectors to the connecting points between columns and beams.

Steel erection

The superstructure of both buildings and civil engineering structures often involves erection of substantial steel frames, sometimes of great height. While responsibility for ensuring safe access for steel erectors who assemble these frames rests principally with the management of steel erection contractors, their difficult job can be made easier by the designers of the steel work. Designers should ensure that patterns of bolt holes are simple and facilitate easy insertion of bolts; the pattern of joints and bolt holes should be as uniform as possible throughout the frame; rests or perches should be provided on columns at joints with beams, so that the ends of beams may rest still while steel erectors are inserting bolts. As far as possible, the design should ensure that access stairs form part of the early frame so that steel erectors have to rely less on ladders and beams for access.

Also, the design should provide for holes to be drilled in suitable places in the columns during fabrication and before the steel is delivered to site, which will permit securing of taut wire ropes, to which steel erectors wearing safety harnesses may secure their running lines. The aim should be to get floor plates in place in steel frames as soon as possible, to reduce the amount of time that steel erectors have to rely on safety lines and harnesses or ladders. If the steel frame has to remain open and without floors while erection continues to higher levels, then safety nets should be slung below the various working levels. As far as possible, the design of the steel frame and the working practices of the steel erectors should minimize the extent to which workers have to “walk steel”.

Roof-work

While raising the walls is an important and hazardous stage in erecting a building, putting the roof in place is equally important and presents special hazards. Roofs are either flat or pitched. With flat roofs the principal hazard is of persons or materials falling either over the edge or down openings in the roof. Flat roofs are usually constructed either from wood or cast concrete, or slabs. Flat roofs must be sealed against entry of water, and various materials are used, including bitumen and felt. All materials required for the roof have to be raised to the required level, which may require goods hoists or cranes if the building is tall or the quantities of covering and sealant are substantial. Bitumen may have to be heated to assist spreading and sealing; this may involve taking on to the roof a gas cylinder and melting pot. Roof-workers and persons beneath can be burned by the heated bitumen and fires can be started involving the roof structure.

The hazard from falls can be prevented on flat roofs by erecting temporary edge protection in the form of guard rails of dimensions similar to the guard rails in scaffolds. If the building is still surrounded by external scaffolding, this can be extended up to roof level, to provide edge protection for roof-workers. Falls down openings in flat roofs can be prevented by covering them or, if they have to remain open, by erecting guard rails round them.

Pitched roofs are most commonly found on houses and smaller buildings. The pitch of the roof is achieved by erecting a wooden frame to which the outer covering of the roof, usually clay or concrete tiles, is attached. The pitch of the roof may exceed 45 above horizontal, but even a shallower pitch presents hazards when wet. To prevent roof-workers from falling while fixing battens, felt and tiles, roof ladders should be used. If the roof ladder cannot be secured or supported at its bottom end, it should have a properly designed ridge-iron that will hook over the ridge tiles. Where there is doubt about the strength of ridge tiles, the ladder should be secured by means of a rope from its top rung, over the ridge tiles and down to a strong anchorage point.

Fragile roofing materials are used on both pitched and curved or barrel roofs. Some roof lights are made of fragile materials. Typical materials include sheets of asbestos cement, plastic, treated chipboard and wood-wool. Because roof-workers frequently step through sheets they have just laid, safe access to where the sheets are to be laid, and a safe position from which to do it, are required. This is usually in the form of a series of roof ladders. Fragile roofing materials present an even greater hazard to maintenance workers, who may be unaware of their fragile nature. Designers and architects can improve the safety of roof-workers by not specifying fragile materials in the first place.

Laying of roofs, even flat roofs, can be dangerous in high winds or heavy rain. Materials such as sheets, normally safe to handle, become dangerous in such weather. Unsafe roof-work not only endangers roof-workers, but also presents hazards to the public beneath. Erection of new roofs is hazardous, but, if anything, maintenance of roofs is even more dangerous.

Renovation

Renovation includes both maintenance of the structure and changes to it during its life. Maintenance (including cleaning and repainting of woodwork or other exterior surfaces, repointing of cement and repairs to walls and the roof) presents hazards from falling similar to those of erection of the structure because of the need to gain access to high parts of the structure. Indeed, the hazards may be greater because during smaller, short-duration maintenance jobs, there is a temptation to cut costs on provision of safe access equipment, for example, by trying to do from a ladder what can be safely done only from a scaffold. This is especially true of roof work, where replacement of a tile may take only minutes but there is still the possibility of a worker falling to his or her death.

Maintenance and cleaning

Designers, especially architects, can improve safety for maintenance and cleaning workers by taking into account in their designs and specifications the need for safe access to roofs, to plant rooms, to windows and to other exposed positions on the outside of the structure. Avoiding the need for access at all is the best solution, followed next by permanent safe access as part of the structure, perhaps stairs or a walkway with guard rails or a powered access platform permanently slung from the roof. The least satisfactory situation for maintenance personnel is where a scaffold similar to that used to erect the building is the only way to provide safe access. This will be less of a problem for major, longer duration renovation work, but on short-duration jobs, the cost of full scaffolding is such that there is a temptation to cut corners and use mobile powered access equipment or tower scaffolds where they are unsuitable or inadequate.

If renovation involves major re-cladding of the building or wholesale cleaning using high-pressure water jetting or chemicals, total scaffolding may be the only answer that will not only protect the workers but also allow the hanging of sheeting to protect the public nearby. Protection of workers involved in cleaning using high-pressure water jets includes impervious clothing, boots and gloves, and a face screen or goggles to protect the eyes. Cleaning involving chemicals such as acids will require similar but acid-resistant protective clothing. If abrasives are used to clean the structure a silica-free substance should be used. Since use of abrasives will give rise to dust that may be injurious, approved respiratory equipment should be worn by the workers. Repainting of windows in a tall office building or block of flats cannot be done safely from ladders, although this is usually possible on domestic housing. It will be necessary to provide either scaffolding or to hang suspended scaffolds such as cradles from the roof, ensuring that suspension points are adequate.

Maintenance and cleaning of civil engineering structures, like bridges, tall chimneys or masts may involve working at such heights or in such positions (e.g., above water) that prohibit the erection of a normal scaffold. As far as possible, work should be done from a fixed scaffold slung or cantilevered from the structure. Where this is not possible, work should be done from a properly suspended cradle. Modern bridges often have their own cradles as parts of the permanent structure; these should be checked fully before being used for a maintenance job. Civil engineering structures are often exposed to the weather, and work should not be permitted in high winds or heavy rain.

Window cleaning

Window cleaning presents its own hazards, especially where it is done from the ground on ladders, or with improvised arrangements for access on taller buildings. Window cleaning is not usually regarded as part of the construction process, and yet is a widespread operation that can endanger both the window cleaners and the public. Safety in window cleaning is, however, influenced by one part of the construction process-design. If architects fail to take into account the need for safe access, or alternatively to specify windows of a design that can be cleaned from inside, then the job of the window cleaning contractor will be much more hazardous. Whilst designing out the need for external window cleaning or installing proper access equipment as part of the original design may initially cost more, there should be considerable savings over the life of the building in maintenance costs and a reduction in hazards.

Refurbishment

Refurbishment is an important and hazardous aspect of renovation. It takes place when for example, the essential structure of the building or bridge is left in place but other parts are repaired or replaced. Typically in domestic housing, refurbishment involves stripping out windows, possibly floors and stairs, along with wiring and plumbing, and replacing them with new and usually upgraded items. In a commercial office building, refurbishment involves windows and possibly floors, but also is likely to involve stripping out and replacing cladding to a framed building, installing new heating and ventilation equipment and lifts or total rewiring.

In civil engineering structures such as bridges, refurbishment may involve stripping the structure back to its basic frame, strengthening it, renewing parts and replacing the roadway and any cladding.

Refurbishment presents the usual hazards to construction workers: falling and falling materials. The hazard is made more difficult to control where the premises remain occupied during refurbishment, as is often the case in domestic premises such as blocks of flats, when alternative accommodations to house occupants are simply not available. In that situation the occupants, especially children, face the same hazards as construction workers. There may be hazards from power cables to portable tools such as saws and drills required during refurbishment. It is important that the work be carefully planned to minimize hazards to both workers and the public; the latter need to know what will be going on and when. Access to rooms, stairs or balconies where work is to be carried out should be prevented. Entrances to blocks of flats may have to be protected by fans to protect persons from falling materials. At the close of the working shift, ladders and scaffolds should be removed or closed off in a manner that does not allow children to get onto them and endanger themselves. Similarly, paints, gas cylinders and power tools should be removed or stored safely.

In occupied commercial buildings where services are being refurbished, it should not be possible for liftway doors to be opened. If refurbishment interferes with fire and emergency equipment, special arrangements need to be made to warn both occupants and workers if fire breaks out. Refurbishment of both domestic and commercial premises may require removal of asbestos-containing materials. This presents major health risks to the workers and the occupants when they return. Such asbestos removal should be carried out only by specially trained and equipped contractors. The area where asbestos is being removed will need to be sealed off from other parts of the building. Before the occupants return to areas from which asbestos has been stripped, the atmosphere in those rooms should be monitored and the results evaluated to ensure that asbestos fibre levels in air are below permissible levels.

Usually the safest way to carry out refurbishment is to totally exclude occupants and members of the public; however, this is sometimes simply not practicable.

Utilities

Provision of utilities in buildings, such as electricity, gas, water and telecommunications, is usually carried out by specialist subcontractors. Principal hazards are falls due to poor access, dust and fumes from drilling and cutting and electric shock or fire from electrical and gas services. The hazards are the same in houses, only on a smaller scale. The job is easier for contractors if proper allowance has been made by the architect in designing the structure to accommodate the utilities. They require space for ducts and channels in walls and floors plus sufficient additional space for installers to operate effectively and safely. Similar considerations apply to maintenance of utilities after the building has been taken into use. Proper attention to the detailing of ducts, channels and openings in the initial design of the structure should mean that these are either cast or built into the structure. It will then not be necessary for construction workers to chase out channels and ducts or to open up holes using power tools, which create large quantities of harmful dust. If adequate space is provided for heating and air conditioning ducts and equipment, the job of the installers is both easier and safer because it is then possible to work from safe positions rather than, for example, standing on boards wedged across the inside of vertical ducts. If lighting and wiring have to be installed overhead in rooms with high ceilings, contractors may need scaffolding or tower scaffolds in addition to ladders.

Installation of utility services should be conform to recognized local standards. These should, for example, cover all safety aspects of electrical and gas installations so that contractors are in no doubt as to standards required for wiring, insulation, earthing (grounding), fusing, isolation and, for gas, protection for pipework, isolation, adequate ventilation and fitting of safety devices for flame failure and loss of pressure. Failure by contractors to deal adequately with these matters of detail in the installation or maintenance of utilities will create hazards for both their own workers and the occupants of the building.

Interior finishing

If the structure is of brick or concrete, the interior finish may require initial plastering to provide a surface which can be painted. Plastering is a traditional craft trade. The principal hazards are severe strain to the back and arms from handling bagged material and plaster boards and then the actual plastering process, especially when the plasterer is working overhead. After plastering, surfaces may be painted. The hazard here is from vapours given off by thinners or solvents and sometimes from the paint itself. If possible, water-based paints should be used. If solvent-based paints have to be used, the rooms should be well ventilated, if necessary by the use of fans. If materials used are toxic and adequate ventilation cannot be achieved, then respiratory and other personal protection should be worn.

Sometimes interior finishing may require the fixing of cladding or linings to the walls. If this involves use of cartridge guns to secure the panels to timber studding the hazard will principally arise from the way the gun is operated. Cartridge-driven nails can easily be fired through walls and partitions or can ricochet on striking something hard. Contractors need to plan this work carefully, if necessary excluding other persons from the vicinity.

Finishing may require tiles or slabs of various materials to be fixed to walls and floors. Cutting large quantities of ceramic tiles or stone slabs using powered cutters gives rise to great quantities of dust and should either be done wet or in an enclosed area. The principal hazard with tiles, including carpet tiles, arises from the need to stick them in position. Adhesives used are solvent based and give off vapours that are harmful, and in an enclosed space they can be flammable. Unfortunately, those laying tiles are kneeling down low over the point where vapours are given off. Water-based adhesives should be used. Where solvent-based adhesives have to be used, rooms should be well ventilated (fan assisted), the quantity of adhesives brought into the workroom should be kept to a minimum and drums should be decanted into smaller tins used by tilers outside the workroom.

If finishing requires installations of sound- or heat-insulation materials, as is often the case in blocks of flats and commercial buildings, these may be in the form of sheets or slabs that are cut, blocks that are laid and fixed together or to a surface by a cement or in a wet form that is sprayed. Hazards include exposure to dust that may both irritate and be harmful. Asbestos-containing materials should not be used. If artificial mineral fibres are used, respiratory protection and protective clothing should be worn to prevent skin irritation.

Fire hazards in interior finishing

Many of the finishing operations in a building involve use of materials that greatly increase the fire hazard. The basic structure may be relatively non-flammable steel, concrete and brick. However, the finishing trades introduce wood, possibly paper, paints and solvents.

At the same time that interior finishing is being performed work may be going on nearby using electric powered tools, or the electrical services may be being installed. Nearly always there is a source of ignition for flammable vapour and materials used in finishing. Many very costly fires have been ignited during finishing, putting workers at risk and usually damaging not only the finishing of the building but also its main structure. A building undergoing finishing is an enclosure in which possibly hundreds of workers are using flammable materials. The main contractor should ensure that proper arrangements are made to provide and protect means of escape, keep access routes clear from obstructions, reduce the quantity of flammable materials stored and in use inside the building, warn contractors of fire and, when necessary, evacuate the building.

Exterior finishing

Some of the materials used in internal finishing may also be used on the exterior, but exterior finishing is generally concerned with cladding, sealing and painting. The cement courses in brick and block work are generally “pointed” or finished as the bricks or blocks are laid and require no further attention. The exterior of walls may be cement that is to be painted or have an application of a layer of small stones, as in stucco or roughcast. Exterior finishing, like general construction work, is done outdoors and is subject to the effects of the weather. By far the greatest hazard is the risk of falling, often heightened by difficulties in handling components and materials. Use of paints, sealants and adhesives containing solvents is less of a problem than in internal finishing because natural ventilation prevents a build-up of harmful or flammable concentrations of vapour.

Again, designers can influence the safety of exterior finishing by specifying cladding panels that can be safely handled (i.e., not too heavy or large) and making arrangements so that cladding can be done from safe positions. The frames or floors of the building should be designed to incorporate features like lugs or recesses that permit easy landing of cladding panels, especially when placed in position by crane or hoist. Specification of materials such as plastics for window frames and fascias eliminates the need for painting and repainting and reduces subsequent maintenance. This benefits the safety of both construction workers and the occupants of house or flat.

Landscaping

Landscaping on a large scale may involve earth-moving similar to that involved in highway and canal works. It may require deep excavations to install drains; extensive areas may have to be slabbed or concreted; rocks may have to be moved. Finally, the client may wish to create the impression of a mature, well-established development, so that fully grown trees will be planted. All of this requires excavation, digging and loading. It often also requires considerable lifting capacity.

Landscape contractors are usually specialists who do not spend much of their time working as part of construction contracts. The main contractor should ensure that landscape contractors are brought to the site at an appropriate time (not necessarily towards the end of the contract). Major excavation and pipe laying may best be carried out early in the life of the project, when similar work is being done for the foundations of the building. Landscaping must not undermine or endanger the building or overload the structure by heaping earth on or against it and its outbuildings in a dangerous manner. If topsoil is to be removed and later placed back in position, sufficient space to heap it in a safe manner will have to be provided.

Landscaping may also be required at industrial premises and public utilities for safety and environmental reasons. Around a petrochemical plant it may be necessary to level off the ground or provide a particular direction of slope, possibly covering the ground with stone chips or concrete to prevent the growth of vegetation. On the other hand, if landscaping around industrial premises is intended to improve appearance or environmental reasons (e.g., to reduce noise or hide an unsightly plant), it may require embankments and erection of screens or planting of trees. Highways and railroad tracks today have to include features that will reduce noise if they are near urban areas or hide the operations if they are in environmentally sensitive areas. Landscaping is not just an afterthought, because as well as improving the appearance of the building or plant, it may, depending on the nature of the development, preserve the environment and improve safety generally. Therefore, it needs to be designed and planned as an integral part of the project.

Demolition

Demolition is perhaps the most dangerous construction operation. It has all the hazards of working at heights and being struck by falling materials, but it is carried out in a structure that has been weakened either as part of the demolition, or as the result of storms, damage produced by flood, fire, explosions or simple wear and tear. The hazards during demolition are falls, being struck or buried in falling material or by the unintentional collapse of the structure, noise and dust. One of the practical problems with ensuring health and safety during demolition is that it can proceed very rapidly; with modern equipment a great deal can be demolished in a couple of days.

There are three principal ways of demolishing a structure: take it down piecemeal; knock it or push it down; or blast it down using explosives. Choice of method is dictated by the condition of the structure, its surroundings, the reasons for the demolition and cost. Use of explosives will usually not be possible when other buildings are close by. Demolition needs to be planned as carefully as any other construction process. The structure to be demolished should be thoroughly surveyed and any drawings obtained, so that as much information as possible on the nature of the structure, its method of construction and materials is available to the demolition contractor. Asbestos is commonly found in buildings and other structures that are to be demolished and requires contractors who are specialists in handling it.

Planning of the demolition process should ensure that the structure is not overloaded or unevenly loaded with debris and that there are suitable openings for chuting of debris for safe removal. If the structure is to be weakened by cutting parts of the frame (especially reinforced concrete or other highly stressed types of structure) or by removing parts of a building such as floors or internal walls, this must not so weaken the structure that it may collapse unexpectedly. Debris and scrap materials should be planned to fall in such a way that they can be removed or saved safely and appropriately; sometimes the cost of a demolition job depends on salvaging valuable scrap or components.

If the structure is to be demolished piecemeal (i.e., taken down bit by bit), without using remotely operated powered picks and cutters, workers will inevitably have to do the job using hand tools or hand-held powered tools. This means they may have to work at heights on exposed faces or above openings created to allow debris to fall. Accordingly, temporary scaffold working platforms will be necessary. The stability of such scaffolds should not be endangered by removal of parts of the structure or fall of debris. If stairs are no longer available for use by workers because the stairwell opening is being used to chute debris external ladders or scaffolds will be necessary.

Removal of points, spires or other tall features on the top of buildings is sometimes done most safely by workers operating from properly-designed buckets slung from the safety hook of a crane.

In piecemeal demolition, the safest method is to take the building down in a sequence opposite to the way it was put up. Debris should be removed regularly so that working places and access do not become obstructed.

If the structure is to be pushed or pulled over or knocked down, it is usually pre-weakened, with the attendant hazards. Pulling down is sometimes done by removing floors and internal walls, attaching wire ropes to strong points on the upper parts of the building and using an excavator or other heavy machine to pull on the wire rope. There is a real hazard from flying wire ropes if they break due to overload or failure of the anchorage point on the building. This technique is not suitable for very tall buildings. Pushing over, again after pre-weakening, involves use of heavy plant such as crawler-mounted grabs or pushers. The cabs of such equipment should be shielded to prevent drivers from being injured by falling debris. The site should not be allowed to become so obstructed by fallen debris as to create instability for machine used to pull or push the building down.

Balling

The most common form of demolition (and if done properly, in many ways the safest) is “balling” down, using a steel or concrete ball suspended from a hook on a crane with a jib strong enough to withstand the special strains imposed by balling. The jib is moved sideways and the ball swung against the wall to be demolished. The principal hazard is trapping the ball in the structure or debris, then trying to extricate it by raising the crane hook. This grossly overloads the crane, and either the crane cable or the jib may fail. It may be necessary for a worker to climb up to where the ball is wedged and free it. However, this should not be done if there is a risk of that part of the building collapsing on the worker. Another hazard associated with less skilled crane operators is balling too hard, so that unintended parts of the building are accidentally brought down.

Explosives

Demolition using explosives can be done safely, but it must be carefully planned and carried out only by experienced workers under competent supervision. Unlike military explosives, the purpose of blasting to demolish a building is not to totally reduce the building to a heap of rubble. The safe way to do it is, after pre-weakening, to use no more explosive than will safely bring down the structure so that debris can be safely removed and scrap salvaged. Contractors carrying out blasting should survey the structure, obtain drawings and as much information as possible on its method of construction and materials. Only with this information is it possible to determine whether blasting is appropriate in the first place, where charges should be placed, how much explosive should be used, what steps may be necessary to prevent ejection of debris and what sort of separation zones will be required around the site to protect workers and the public. If there are a number of explosive charges, electrical shotfiring with detonators will usually be more practical, but electrical systems can develop faults, and on simpler jobs the use of detonator cord may be more practical and safer. Aspects of blasting that require careful preliminary planning are what is to be done if there is either a misfire or if the structure does not fall as planned and is left hanging in a dangerous state of instability. If the job is close to housing, highways or industrial developments, the people in the area should be warned; local police are usually involved in clearing the area and halting pedestrian and vehicular traffic.

Tall structures like television towers or cooling towers may be felled using explosives, providing they have been pre-weakened so that they fall safely.

Demolition workers are exposed to high noise levels because of noisy machinery and tools, falling debris or blasts from explosives. Hearing protection will usually be required. Dust is produced in large quantities as buildings are demolished. A preliminary survey should ascertain whether and where lead or asbestos are present; if possible, these should be removed before the start of the demolition. Even in the absence of such notable hazards, dust from demolition is often irritating if not actually injurious, and an approved dust mask should be worn if the work area cannot be kept wet to control the dust.

Demolition is both dirty and arduous, and a high level of welfare facilities should be provided, including toilets, washplaces, cloakrooms for both normal clothing and work clothes and a place to shelter and take meals.

Dismantling

Dismantling differs from demolition in that part of the structure or, more commonly, a large piece of machinery or equipment is disassembled and removed from site. For example, removal of part or the whole of a boiler from a power house in order to replace it, or replacement of a steel girder bridge span is dismantling rather than demolition. Workers involved in dismantling tend to do a great deal of oxyacetylene or gas cutting of steel work, either to remove parts of the structure or to weaken it. They may use explosives to knock over an item of equipment. They use heavy lifting machinery to remove large girders or pieces of machinery.

Generally, workers engaged in such activities face all the same hazards of falling, things falling on them, noise, dust and harmful substances that are met in demolition proper. Contractors who carry out dismantling require a sound knowledge of structures to ensure that they are taken apart in a sequence that does not cause a sudden and unexpected collapse of the main structure.

Overwater Work

Work over and alongside water as in bridge building and maintenance, in docks and sea and river defence work presents special hazards. The hazard may be increased if the water is flowing or tidal, as opposed to still; rapid water movement makes it more difficult to rescue those who fall in. Falling in water presents the hazard of drowning (in even quite shallow water if the person is injured in the fall as well as hypothermia if the water is cold and infection if it is polluted).

The first precaution is to prevent workers from falling by ensuring that there are proper walkways and workplaces with guard rails. These should not be allowed to become wet and slippery. If walkways are not possible, as perhaps in the earlier stages of steel erection, the workers should wear harnesses and ropes attached to secure anchorage points. These should be supplemented with safety nets slung beneath the work position. Ladders and grablines should be provided to assist fallen workers to climb out of the water, as, for example, at the edges of docks and sea defences. While workers are not on a properly boarded out platform with guard rails or are travelling to and from their worksite, they should wear buoyancy aids. Lifebuoys and rescue lines should be placed at regular intervals along the edge of the water.

Work in docks, river maintenance and sea defences often involves use of barges to carry piling rigs and excavators to remove dredged out spoil. Such barges are equivalent to working platforms and should have suitable guard rails, lifebuoys and rescue and grab lines. Safe access from the shore, dock or river side should be provided in the form of walkways or gangways with guard rails. This should be so arranged as to adjust safely with the changing levels of tidal water.

Rescue boats should be available, fitted with grablines and with lifebuoys and rescue lines on board. If the water is cold or flowing, the boats should be continuously staffed, and should be powered and ready to carry out a rescue mission immediately. If water is polluted with industrial effluent or sewage, arrangements should be made to transport those who fall into such water to a medical centre or hospital for immediate treatment. Water in urban areas may be contaminated with the urine of rats, which may infect open skin abrasions, causing Weil’s disease.

Work over water is often carried out in locations that are subject to strong winds, driving rain or icing conditions. These increase the risk of falls and heat loss. Severe weather may make it necessary to stop work, even in the middle of a shift; to avoid excessive heat loss it may be necessary to supplement normal wet or cold weather protective clothing with thermal underclothing.

Underwater Work

Diving

Diving is a specialized form of working underwater. The hazards faced by divers are drowning, decompression sickness (or the “bends”), hypothermia from the cold and becoming trapped below water. Diving may be required during construction or maintenance of docks, sea and river defences and at piers and abutments of bridges. It is often required in waters where visibility is poor or in locations where there is a risk of entanglement for the diver and his or her equipment. Diving may be carried out from dry land or from a boat. If the work requires only a single diver, then as a minimum a team of three will be required for safety. The team consists of the diver in the water, a fully equipped standby diver ready to enter the water immediately in the event of an emergency and a diving supervisor in charge. The diving supervisor should be at the safe position on land or in the boat from which the diving is to take place.

Diving at depths less than 50 m is usually carried out by divers wearing wet suits (i.e., suits that do not exclude water) and wearing self-contained underwater breathing apparatus with an open face mask (i.e., SCUBA diving gear). At depths greater than 50 m or in very cold water, it will be necessary for divers to wear suits that are heated by a supply of pumped warm water and closed diving masks, and equipment for breathing not compressed air but air plus a mixture of gases (i.e., mixed-gas diving). Divers must wear a suitable safety line and be able to communicate with the surface and in particular with their diving supervisor. The local emergency services should be advised by the diving contractor that diving is to take place.

Both divers and equipment require examination and testing. Divers should be trained to a recognized national or international standard, firstly and always for air diving and secondly for mixed-gas diving if this is to take place. They should be required to provide written evidence of successful completion of a diver training course. Divers should have an annual medical examination with a doctor experienced in hyperbaric medicine. Each diver should have a personal logbook in which a record of physicals and of his or her dives is kept. If a diver has been suspended from diving as a result of the physical, this also should be recorded in the logbook. A diver under suspension should not be allowed to dive or act as a standby diver. Divers should be asked by their diving supervisor if they are well, especially whether they have any respiratory illness, before being allowed to dive. Diving equipment, suits, belts, ropes, masks and cylinders and valves should be checked every day before use.

Satisfactory operation of cylinder and demand valves should be demonstrated by divers for their diving supervisor.

In the event of an accident or other reasons for the sudden ascent of a diver to the surface, he or she may experience the bends or be at risk of them and require to be recompressed. For this reason it is desirable that the whereabouts of a medical or other decompression chamber suitable for divers is located before diving starts. Those in charge of the chamber should be alerted to the fact that diving is taking place. Arrangements should be available for the rapid transport of divers requiring decompression.

Because of their training and equipment, plus all the backup required for safety, use of divers is very expensive, and yet the amount of time they are actually working on the riverbed may be limited. For these reasons there are temptations for diving contractors to use untrained or amateur divers or a diving team that is deficient in numbers and equipment. Only reputable diving contractors should be used for diving in construction, and particular care needs to be taken over the selection of divers who claim to have been trained in other countries where standards may be lower.

Caissons

Caissons are rather like a large inverted saucepans whose rims sit on the bed of the harbour or river. Sometimes open caissons are used, which, as their name implies, have an open top. They are used on land to sink a shaft into soft ground. The bottom edge of the caisson is sharpened, workers excavate inside the caisson, and it sinks into the ground as soil is removed, thus creating the shaft. Similar open caissons are used in shallow water, but their depth may be extended by adding sections on top as the caisson sinks into the river or harbour bed. Open caissons rely on pumping to control the entry of water and soil into the base of the caisson. For deeper work still, a closed caisson will have to be used. Compressed air is pumped into it to displace the water, and workers are able to enter through an airlock, usually on top, and go down to work in air on that bed. Workers are able to work under water but are freed from the constraints of wearing diving equipment, and visibility is much better. The hazards in “pneumatic” caisson work are the bends and, as in all types of caisson including the simplest open caisson, drowning if water gets into the caisson through any structural failure or loss of air pressure. Because of the risk of entry of water, means of escape such as ladders up to the entry point should be available at all times in both open and pneumatic caissons.

Caissons should be inspected daily before they are used by someone competent and experienced in caisson work. Caissons may be raised and lowered as single units by heavy lifting equipment, or they may be constructed from components in the water. Construction of caissons should be under the supervision of a similarly competent person.

Tunnelling underwater

Tunnelling, when carried out in porous ground beneath water, may need to be done under compressed air. Driving tunnels for public transportation systems in city centres beneath rivers is a widespread practice, owing to lack of space above ground and environmental considerations. Compressed air working will be as limited as possible because of its danger and inefficiency.

Tunnels beneath water in porous ground will be lined with concrete or cast iron rings and grouted. But at the actual heading where the tunnel is being dug and in the short length where tunnel rings are being placed in position, there will not be a sufficiently water-tight surface for the work to proceed without some means of keeping out the water. Working under compressed air may still be used for the tunnel head and ring or segment placing part of the tunnel driving and lining process. Workers involved in driving the heading (i.e., on a TBM operating the rotating cutting head) or using hand tools, and those operating ring and segment placing equipment, will have to pass through an airlock. The rest of the now lined tunnel will not require to be compressed, and thus there will be easier transit of personnel and materials.

Tunnellers who have to work in compressed air face the same hazard of the bends as divers and caisson workers. The airlock giving access to the compressed-air workings should be supplemented by a second airlock through which workers pass at the end of the shift to be decompressed. If there is only a single airlock, this may create bottlenecks and also be dangerous. Hazards arise if workers are not decompressed sufficiently slowly at the end of their shift or if lack of airlock capacity holds up entry of vital equipment to the workings under pressure. Airlocks and decompression chambers should be under the supervision of a competent person experienced in compressed-air tunnelling and proper decompression.

Back

The term construction industry is used worldwide to cover what is a collection of industries with very different practices, brought together temporarily on the site of a building or civil engineering job. The scale of operations ranges from a single worker carrying out a job lasting minutes only (e.g., replacing a roof tile with equipment consisting of a hammer and nails and possibly a ladder) to vast building and civil engineering projects lasting many years that involve hundreds of different contractors, each with their own expertise, plant and equipment. However, despite the enormous variation in scale and complexity of operations, the major sectors of the construction industry have a great deal in common. There is always a client (known sometimes as the owner) and a contractor; except for the very smallest jobs, there will be a designer, either an architect or engineer, and if the project involves a range of skills, it will inevitably require additional contractors working as subcontractors to the main contractor (see also the article “Organizational factors affecting health and safety” in this chapter). While small-scale domestic or agricultural buildings may be built on the basis of an informal agreement between the client and builder, the vast majority of building and civil engineering work will be carried out under the terms of a formal contract between the client and contractor. This contract will set out details of the structure or other work that the contractor is to provide, the date by which it is to be built and the price. Contracts may contain a great deal besides the job, the time and the price, but those are the essentials.

The two broad categories of construction projects are building and civil engineering. Building applies to projects involving houses, offices, shops, factories, schools, hospitals, power and railway stations, churches and so on—all those kinds of structures that in everyday speech we describe as “buildings”. Civil engineering applies to all the other built structures in our environment, including roads, tunnels, bridges, railways, dams, canals and docks. There are structures that appear to fall into both categories; an airport involves extensive buildings as well as civil engineering in the creation of the airfield proper; a dock may involve warehouse buildings as well excavation of the dock and raising of the dock walls.

Whatever the type of structure, building and civil engineering both involve certain processes such as building or erection of the structure, its commissioning, maintenance, repair, alteration and ultimately its demolition. This cycle of processes occurs regardless of the type of structure.

Small Contractors and the Self-employed

While there are variations from country to country, construction is typically an industry of small employers. As many as 70 to 80% of contractors employ less than 20 workers. This is because many contractors start out as a single tradesperson working alone on small-scale jobs, probably domestic ones. As their business expands, such tradespeople start to employ a few workers themselves. The workload in construction is rarely consistent or predictable, as some jobs finish and others start up at different times. There is a need in the industry to be able to move groups of workers with particular skills from job to job as the work requires. Small contractors fulfil this role.

Alongside the small contractors there is a population of self-employed workers. Like agriculture, construction has a very high proportion of self-employed workers. These again are usually tradespeople, such as carpenters, painters, electricians, plumbers and bricklayers. They are able to find a place in either small-scale domestic work or as part of the workforce on bigger jobs. In the boom construction period of the late 1980s, there was an increase in workers claiming to be self-employed. This was partly because of tax incentives for the individuals concerned and use by contractors of so-called self-employed who were cheaper than employees. Contractors were not faced with the same level of social security costs, were not required to train self-employed persons and could get rid of them more easily at the end of jobs.

The presence in construction of so many small contractors and self-employed individuals tends to militate against effective management of health and safety for the job as a whole and, with such a transitory workforce, certainly makes it more difficult to provide proper safety training. Analysis of fatal accidents in the United Kingdom over a 3-year period showed that about half the fatal accidents happened to workers who had been onsite for a week or less. The first few days on any site are especially hazardous to construction workers because, however experienced they may be as tradespeople, each site is a unique experience.

Public and Private Sectors

Contractors may be part of the public sector (e.g., the works department of a city or district council) or they are part of the private sector. A considerable amount of maintenance used to be done by such public works departments, especially on housing, schools and roads. Recently there has been a move to encourage greater competition in such work, partly as a result of pressures for better value for money. This has led firstly to a reduction in the size of public works departments, even their total disappearance in some places, and to the introduction of mandatory competitive tendering. Jobs previously done by public works departments are now done by private-sector contractors under severe “lowest tender wins” conditions. In their need to cut costs, contractors may be tempted to reduce what are seen as overheads such as safety and training.

The distinction between public and private sectors may also apply to clients. Central and local government (along with transportation and public utilities if under the control of central or local government) may all be clients for construction. As such they would generally be thought to be in the public sector. Transportation and utilities run by corporations would usually be considered to be in the private sector. Whether a client is in the public sector sometimes influences attitudes towards inclusion of some items of safety or training in the cost of construction work. Recently public- and private-sector clients have been under similar constraints as regards competitive tendering.

Work across National Boundaries

An aspect of public-sector contracts of increasing importance is the need for tenders to be invited from beyond national boundaries. In the European Union, for example, large-scale contracts beyond a value set out in Directives, must be advertised within the Union so that contractors from all member countries may tender. The effect of this is to encourage contractors to work across national boundaries. They are then required to work in accordance with the local national health and safety laws. One of the aims of the European Union is to harmonize standards between member states in health and safety laws and their application. Major contractors working in parts of the world subject to similar regimes must therefore be familiar with health and safety standards in those countries where they carry out work.

Designers

In buildings, the designer is usually an architect, although on small-scale domestic housing, contractors sometime provide such design expertise as is necessary. If the building is large or complex, there may be architects dealing with design of the overall scheme as well as structural engineers concerned with design of, for example, the frame, and specialist engineers involved with design of the services. The architect for the building will ensure that sufficient space is provided in the right places in the structure to permit installation of plant and services. Specialist designers will be concerned to ensure that the plant and services are designed to operate to the required standard when installed in the structure in the places provided by the architect.

In civil engineering, the lead in design is more likely to be taken by a civil or structural engineer, although in high-profile jobs where visual impact may be an important factor, an architect may have an important role in the design team. In tunnelling, railways and highways, the lead in design is likely to be taken by structural or civil engineers.

The role of the developer is to seek to improve the utilization of land or buildings and profit from that improvement. Some developers simply sell the improved land or buildings and have no further interest; others may retain ownership of land or even buildings and reap a continuing interest in the form of rents that are greater than before the improvements.

The skill of the developer is to identify sites either as empty land or under-utilized and out-of-date buildings where application of construction skills will improve their value. The developer may use his or her own finances, but perhaps more often exercises further skills in identifying and bringing together other sources of finance. Developers are not a modern phenomenon; the expansion of cities over the last 200 years owes a great deal to developers. Developers may themselves be clients for the construction work, or they may simply act as agents for other parties who provide finance.

Types of Contract

In the traditional contract, the client arranges for a designer to prepare a full design and specifications. Contractors are then invited by the client to tender or bid for doing the job in accordance with the design. The role of the contractor is largely confined to construction proper. The contractor’s involvement in questions of design or specification is then mainly a matter of seeking such changes as will make it easier or more efficient to build—to improve “buildability”.

The other common arrangement in construction is the design and build contract. The client requires a building (perhaps an office block or shopping development) but has no firm ideas on detailed aspects of its design other than the size of site, number of persons to be accommodated or scale of activities to be carried out in it. The client then invites tenders from either designers or contractors to submit both design and construction proposals. Contractors working in design and build either have their own design organization or have close links with an external designer who will work for them on the job. Design and build may involve two stages in design: an initial stage where a designer prepares an outline scheme which is then put out to tender; and a second stage where the successful design and build contractor will then carry out further design on detailed aspects of the job.

Maintenance and emergency contracts cover a wide variety of arrangements between clients and contractors and represent a significant proportion of the work of the construction industry. They generally run for a fixed period, require the contractor to do certain types of work or to work on a “call-off” basis (i.e., work that the client calls the contractor in to do). Emergency contracts are widely used by public authorities who are responsible for providing a public service that ought not to be interrupted; government agencies, public utilities and transportation systems make wide use of them. Operators of factories, particularly those with continuous processes such as petrochemicals, also make wide use of emergency contracts to deal with problems in their facilities. Having entered such a contract, the contractor undertakes to make available suitable workers and plant to carry out the work, often at very short notice (e.g., in the case of emergency contracts). The advantage to the client is that he or she does not need to retain workers on payroll or have plant and equipment that may only occasionally be used to deal with maintenance and emergencies.

Pricing of maintenance and emergency contracts may be on the basis of a fixed sum per annum, or on the basis of time spent carrying out work, or some combination.

Perhaps the most common publicly known example of such contractors is maintenance of roads and emergency repairs to gas main or power supplies that have either failed or been accidentally damaged.

Whatever the form of contract, the same possibilities arise for clients and designers to influence the health and safety of contractors by decisions made in the early stage of the job. Design and build perhaps permits closer liaison between the designer and contractor on health and safety.

Price

Price is always an element in a contract. It may simply be a single sum for the cost of doing the job, such as building a house. Even with a single lump sum, the client may have to pay part of the price in advance of the job starting, to enable the contractor to buy materials. The price may, however, be on a cost-plus basis, where the contractor is to recover his or her costs plus an agreed amount or percentage for profit. This arrangement tends to work to the disadvantage of the client, since there is no incentive for the contractor to keep costs down. The price may also have bonuses and penalties attached to it, so that the contractor will receive more money if, for example, the job is completed earlier than the agreed time. Whatever form the price takes for the job, it is usual for payments to be made in stages as the work progresses, either on completion of certain parts of the job by agreed dates or on the basis of some agreed method of measuring the work. At the end of construction proper, it is common for an agreed proportion of the price to be kept back by the clients until “snags” have been put right or the structure has been commissioned.

During the course of the job, the contractor may encounter problems that were not foreseen when the contract was made with the client. These might require changes to the design, the construction method or the materials. Usually such changes will create extra costs for the contractor, who then seeks to recover from the client on the basis that these items become agreed “variations” from the original contract. Sometimes recovery of the cost of variations can make the difference for the contractor between doing the job at a profit or loss.

The pricing of contracts can affect health and safety if inadequate provision is made in the contractor’s tender to cover the costs of providing safe access, lifting equipment and so on. This becomes even more difficult where, in an attempt to ensure that they obtain value for money from contractors, clients pursue a vigorous policy of competitive tendering. Governments and local authorities apply policies of competitive tendering to their own contracts, and indeed there may be laws requiring that contracts can be awarded only on the basis of competitive tendering. In such a climate, there is always a risk that the health and safety of construction workers will suffer. In cutting costs, clients may resist a reduction in the standard of construction materials and methods, but at the same time be totally unaware that in accepting the lowest tender, they have accepted working methods that are more likely to endanger construction workers. Even in a situation of competitive tendering, contractors submitting tenders should have to make clear to the client that their bid adequately covers the cost of health and safety involved in their proposals.

Developers can influence health and safety in construction in ways similar to clients, firstly by using contractors who are competent in health and safety and architects who take health and safety into account in their designs, and secondly in not automatically accepting the lowest tenders. Developers generally want to be associated only with successful developments, and one measure of success ought to be projects where there are no major health and safety problems during the construction process.

Building Standards and Planning

In the case of buildings, whether housing, commercial or industrial, projects are subject to planning laws that dictate where certain types of development may take place (e.g., that a factory may not be built among houses). Planning laws may be very specific about the appearance, materials and size of buildings. Typically areas identified as industrial zones are the only places where factory buildings may be erected.

Often there are also building regulations or similar standards that specify in precise detail many aspects of the design and specification of buildings—for example, the thickness of walls and timbers, depth of foundations, insulation characteristics, size of windows and rooms, layout of electrical wiring and earthing, layout of plumbing and pipework and many other issues. These standards have to be followed by clients, designers, specifiers and contractors. They limit their choices but at the same time ensure that buildings are built to an acceptable standard. Planning laws and building regulations thus affect the design of buildings and their cost.

Housing

Projects to build housing may consist of a single house or vast estates of individual houses or flats. The client may be each individual householder, who will then normally be responsible for maintenance of his or her own house. The contractor will usually remain responsible for correcting defects in construction for a period of months after building is finished. However, if the project is for many houses, the client may be a public body, either in local or national government, with responsibility for providing housing. There are also large private bodies like housing associations for whom numbers of houses may be built. Public or private bodies with responsibilities for providing housing generally rent the finished houses to occupants, retaining a greater or lesser degree of responsibility for maintenance also. Building projects involving blocks of flats usually have a client for the block as a whole, who then lets out individual flats under a leasing arrangement. In this situation the owner of the block has responsibility for carrying out maintenance but passes on the cost to the tenants. In some countries ownership of individual flats in a block can rest with the occupants of each flat. There has to be some arrangement, sometimes through an estate management contractor, whereby maintenance can be carried out and the necessary costs raised among the occupants.

Often houses are built on a speculative basis, by a developer. Specific clients or occupants of those houses may not have been identified at the outset but come on the scene after construction has begun and purchase or rent the property like any other article. Houses are usually fitted out with electrical, plumbing and drainage services and heating systems; a gas supply may also be laid on. Sometimes in an attempt to cut costs, houses are only partially finished, leaving it to the purchaser to install some of the fittings and to paint or decorate the building.

Commercial Buildings

Commercial buildings include offices, factories, schools, hospitals, shops—an almost endless list of different types of buildings. In most cases these buildings are constructed for a particular client. However, offices and shops are often built on a speculative basis like housing, with the hope of attracting buyers or tenants. Some clients require an office or shop to be totally fitted out to their requirements, but very often the contract is for the structure and main services, with the client making arrangements to fit out the premises using specialist contractors in office and shop fitting.

Hospitals and schools are built for clients who have a clear idea of precisely what they want, and the clients often provide design input into the project. Plant and equipment in hospitals may cost more than the structure and involve a great deal of design that has to satisfy stringent medical standards. National or local government may also play a part in the design of schools by laying down very detailed requirements on space standards and equipment as part of its wider role in education. National governments usually have very detailed standards as to what is acceptable in hospital buildings and plant. Fitting out of hospitals and similarly complex buildings is a form of construction work usually carried out by specialist subcontractors. Such contractors not only require knowledge of health and safety in construction in general, but also need expertise in ensuring that their operations do not adversely affect the hospital’s own activities.

Industrial Construction

Industrial building or construction involves use of the mass- production techniques of manufacturing industry to produce parts of buildings. The ultimate example is the house brick, but normally the expression is applied to building using concrete parts or units that are assembled onsite. Industrial construction expanded rapidly after the Second World War to meet the demand for cheap housing, and it is more commonly found in mass housing developments. Under factory conditions it is possible to mass produce cast units that are consistently accurate in a way that would be virtually impossible under normal site conditions.

Sometimes units for industrial construction are manufactured away from the construction site in factories that may supply a wide area; sometimes, where the individual development is itself very large, a factory is set up onsite to serve that sole site.

Units designed for industrial construction must be structurally strong enough to stand up to being moved, lifted and lowered; they must incorporate anchorage points, or slots to permit safe attachment of lifting tackle, and must also include appropriate lugs or recesses to permit the units to fit together both easily and strongly. Industrial construction demands plant for transporting and lifting units into position and space and arrangements to store units safely when delivered to site, so that units are not damaged and workers are not injured. This technique of building tends to produce visually unattractive buildings, but on a large scale it is cheap; a whole room can be assembled from six cast units with window and door openings in place.

Similar techniques are used to produce concrete units for civil engineering structures like elevated motorways and tunnel linings.

Turn-key Projects

Some clients for industrial or commercial buildings containing extensive complex plant wish simply to walk into a facility that will be up and running from their first day in the premises. Laboratories are sometimes constructed and fitted out on this basis. Such an arrangement is a “turn-key” project, and here the contractor will ensure that all aspects of plant and services are fully operational before handing the project over. The job may be done under a design and build contract so that, in effect, the turn-key contractor deals with everything from design to commissioning.

Civil Engineering and Heavy Construction

The civil engineering of which the public is most aware is work on highways. Some highway work is the creation of new roads on virgin land, but much of it is the extension and repair of existing highways. Contracts for highway work are usually for state or local government agencies, but sometimes roads remain under the control of contractors for some years after completion, during which time they are permitted to charge tolls. If civil engineering structures are being financed by government, then both the design and actual construction will be subject to a high degree of supervision by officials on behalf of government. Contracts for construction of highways are usually let to contractors on the basis of a contractor being responsible for a section of so many kilometres of the highway. There will be a main contractor for each section; but highway construction involves a number of skills, and aspects of the job such as steel work, concrete, shuttering and surfacing may be subcontracted by the main contractor to specialist firms. Highway construction is also sometimes carried out under management contract arrangements, where a civil engineering consultancy will provide management for the job, with all the work being done by subcontractors. Such a management contractor may also have been involved in design of the highway.

Construction of highways requires the creation of a surface whose gradients are suitable for the sort of traffic that will use it. In a generally level terrain, creation of the foundation of the highway may involve earthmoving—that is, shifting soil from cuttings to create embankments, building bridges across rivers and driving tunnels through mountainsides where it is not possible to go round the obstruction. Where labour costs are higher, such operations are carried out using mechanically powered plant such as excavators, scrapers, loaders and lorries. Where labour costs are lower, these processes may be carried out manually by large numbers of workers using hand tools. Whatever the actual methods adopted, highway construction requires high standards of route surveying and planning of the job.

Highway maintenance frequently requires roads to remain in use whilst repairs or improvements are carried out in part of the road. There is thus a hazardous interface between traffic movement and construction operations which makes good planning and management of the job even more important. There are often national standards for signage and coning off of roadworks and requirements as to the amount of separation there should be between construction and traffic, which may be difficult to achieve in a confined area. Control of traffic approaching roadworks is usually the responsibility of the local police, but requires careful liaison between them and the contractors. Highway maintenance creates traffic hold-ups, and accordingly contractors are put under pressure to finish jobs quickly; sometimes there are bonuses for finishing early and penalties for finishing late. Financial pressures must not undermine safety on what is very dangerous work.

Surfacing of highways may involve concrete, stone or tarmacadam. This requires a substantial logistical train to ensure that the required quantities of surfacing materials are in place in the right condition to ensure that surfacing proceeds without interruption. Tarmacadam requires special purpose spreading plant that keeps the surfacing material plastic while spreading it. Where the job is re-surfacing, plant will be required including picks and breakers so that the existing surface is broken up and removed. A final finish is usually applied to the surfaces of highways involving use of heavy powered rollers.

Creation of cuttings and tunnels may require use of explosives and then arrangements to shift the muck displaced by the blasting. The sides of cuttings may require permanent supports to prevent landslides or falls of ground onto the finished road.

Elevated highways often require structures similar to bridges, especially if the elevated section passes through an urban area when space is limited. Elevated highways are often constructed from cast reinforced concrete sections that are either cast in situ or cast in a fabrication area and then shifted to the required position onsite. The work will require large-capacity lifting machinery to lift cast sections, shuttering and reinforcing.

Temporary support arrangements or “falsework” to support sections of either elevated highways or bridges while they are being cast in position need to be designed to take into account the uneven loads imposed by concrete as it is poured. Design of falsework is as important as design of the structure proper.

Bridges

Bridges in remote areas may be simple constructions from timber. More commonly today bridges are from reinforced concrete or steel. They may also be clad in brickwork or stone. If the bridge is to span a considerable gap, whether above water or not, its design will require specialist designers. Using today’s materials, the strength of the bridge span or arch is not achieved by mass material, which would be simply too heavy, but by skilful design. The main contractor for a bridge building job is usually a major general civil-engineering contractor with management expertise and plant. However, specialist subcontractors may deal with major aspects of the job like erection of steel work to form the span or casting or placing cast sections of the span in place. If the bridge is over water, one or both abutments that support the ends of the bridge may themselves have to be constructed in water, involving piling, coffer dams, mass concrete or stone work. A new bridge may be part of a new highway system, and approach roads may have to be built, themselves possibly elevated.

Good design is especially important in bridge building, so that the structure is strong enough to withstand the loads imposed on it in use and to ensure that it will not require maintenance or repair too frequently. The appearance of a bridge is often a very important factor, and again good design can balance the conflicting demands of sound engineering and aesthetics. Provision of safe means of access for maintenance of bridges needs to be taken into account during design.

Tunnels

Tunnels are a specialized form of civil engineering. They vary in size from the Channel Tunnel, with over 100 km of bores from 6 to 8 m in diameter, to mini-tunnels whose bores are too small for workers to enter and which are created by machines launched from access shafts and controlled from the surface. In urban areas, tunnels may be the only way to provide or improve transport routes or to provide water and drainage facilities. The proposed route of the tunnel requires as detailed a survey as possible to confirm the kind of ground that the tunnel workings will be in and whether there will be groundwater. The nature of the ground, the presence of groundwater and the end use of the tunnel all influence the choice of tunnelling method.

If the ground is consistent, like the chalk-clay beneath the English Channel, then machine digging may be possible. If high groundwater pressures are not encountered during pre- construction survey, then it is usually unnecessary for the workings to be pressurized to keep out the water. If working in compressed air cannot be avoided, this adds considerably to costs because airlocks have to be provided, workers need to be allowed time to decompress, and access to workings for plant and materials may be made more difficult. A large tunnel for a road or railway in consistent non-hard-rock ground might be dug using a full-face tunnel-boring machine (TBM). This is really a train of different machines linked together and moving forward on rails under its own power. The front face is a circular cutting head that rotates and feeds spoil back through the TBM. Behind the cutting head are various sections of the TBM that place the segments of tunnel lining rings in position around the surface of the tunnel, grout behind the lining rings and, in a very confined space, provide all the machinery to handle and place ring segments (each weighing some tonnes), remove spoil, bring grout and extra segments forward and house electric motors and hydraulic pumps to power the cutting head and segment-placing mechanisms.

A tunnel in non-hard-rock ground which is not consistent enough to use a TBM, may be dug using equipment such as roadheaders that bite into the face of the heading. Spoil falling from the roadheader onto the tunnel floor are to be collected by diggers and removed by lorry. This technique permits digging of tunnels that are not circular in section. The ground in which such a tunnel is dug will not usually have sufficient strength for it to remain unlined; without some form of lining there might be falls from roof and walls. The tunnel may be lined by liquid concrete sprayed onto a steel mesh held in position by rock bolts (the “New Austrian tunnelling method”) or by cast concrete.

If the tunnel is in hard rock, the heading will be dug by means of blasting, using explosives placed into shot holes drilled into the rock face. The trick here is to use the minimum of blast to achieve a fall of rock in the position and sizes required, thereby making it easier to remove the spoil. On bigger jobs, multiple drills mounted on tracked bases will be used along with diggers and loaders to remove spoil. Hard rock tunnels are often simply trimmed to provide an even surface, but are not then further lined. If the rock surface remains friable with a risk of pieces falling, then a lining will be applied, usually some form of sprayed or cast concrete.

Whatever the method of construction adopted for the tunnel, the effective supply of tunnelling materials and removal of spoil are vital to the successful progress of the job. Large tunnelling jobs may require extensive narrow-gauge construction rail systems to provide logistical support.

Dams

Dams invariably contain large quantities of earth or rock to provide mass to resist the pressure from water behind them; some dams are also covered in masonry or reinforced concrete. Depending on the length of the dam, its construction often requires earthmoving on the very largest scale. Dams tend to be built in remote locations dictated by the need to ensure that water is available at a position where it is technically possible to restrict the flow of the river. Thus temporary roads may have to be built before dam building may start in order to get plant, materials and personnel to the site. Workers on dam projects may be so far from home that full-scale living accommodations have to be provided along with the usual construction site facilities. It is necessary to divert the river away from the site of the workings, and a coffer dam and temporary riverbed may have be created.

A dam constructed simply from earth or rock that has been shifted will require large scale excavation, digging and scraping plant as well as lorries. If the dam wall is covered by masonry or cast concrete, it will be necessary to employ high or long-reach cranes capable of depositing masonry, shuttering, reinforcing and concrete in the right places. A continuous supply of good-quality concrete will be necessary, and a concrete-mixing plant will be necessary alongside the dam workings, with the concrete either handled in batches by crane or pumped to the job.

Canals and docks

Construction and repair of canals and docks contain some aspects of other jobs that have been described, such as roadworks, tunnels and bridges. It is particularly important in canal building for surveying to be to the highest standard before work begins, especially regarding levels and to ensure that material that has had to be dug out can economically be used elsewhere in the job. Indeed the early railway engineers owed a great deal to the experience of canal builders a century before. The canal will require a source for its water and will either tap into a natural source such as a river or lake or create an artificial one in the form of a reservoir. Digging of docks may start on dry land, but sooner or later has to link up to either a river, a canal, the sea or another dock.

Canal and dock building requires excavators and loaders to open up the ground. Spoil may be removed by lorry or water transport may be used. Docks are sometimes developed on ground that has a long history of industrial use. Industrial wastes may have escaped into such ground over many years, and spoil removed in digging or extending the docks will be heavily contaminated. Work in repairing a canal or dock is likely to have to be carried out while adjacent parts of the system are kept in use. The workings may have to rely on coffer dams for protection. Failure of a coffer dam during extension of Newport Docks in Wales in the early years of this century resulted in nearly 100 deaths.

Clients for canals and docks are likely to be public authorities. However, sometimes docks are constructed for corporations alongside their major production plants or for corporate clients to handle a particular type of incoming or outgoing goods (e.g., motor cars). Repair and renovation of canals is nowadays often for the leisure industry. Like dams, both canal and dock construction may be in very remote situations, requiring provision of facilities for workers beyond those of a normal construction site.

Railroads

Construction of railroads or railways historically came after canals and before major highways. Clients in railway construction contracts may be rail operators themselves or governmental agencies, if the railways are financed by government. As with highways, design of a railroad that is economical and safe to build and operate depends on good surveying beforehand. In general, locomotives do not operate effectively on steep gradients, and therefore those designing layout of the track are concerned with avoiding changes in levels, going round or through obstacles rather than over them.

Designers of railroads are subject to two constraints unique to the industry: first, curves in the track layout must generally conform to very large radii (otherwise trains cannot negotiate them); second, all the structures connected with the railway—its bridge arches, tunnels and stations—must be capable of accommodating the envelope of the largest locomotives and rolling stock that will use the track. The envelope is the silhouette of the rolling stock plus clearance to allow safe passage through bridges, tunnels and so on.

Contractors involved in building and repair of railroads require the usual construction plant and effective logistical arrangements to ensure that rail track and ballast as well as construction materials are always available in what may be remote locations. Contractors may use the track they have just laid to run trains supplying the works. Contractors involved in maintenance of existing operational railways have to ensure that their work does not interfere with the operations of the railway and endanger workers or the public.

Airports

The rapid expansion of air transportation since the middle of the 20th century has resulted in one of the biggest and most complex forms of construction: the building and extension of airports.

Clients for airport construction are usually governments at the national or local level or agencies representing the government. Some airports are built for major cities. Airports are rarely for private clients such as business corporations.

Planning the work is sometimes made more difficult because of environmental constraints that have been placed on the project in relation to noise and pollution. Airports require a lot of space, and if they are located in more heavily populated areas, creation of the runways and space for terminal buildings and car parks may require reinstatement of derelict or otherwise difficult land. Building an airport involves levelling a large area, which may require earth moving and even land reclamation, and then construction of a wide variety of often very large buildings, including hangars, maintenance workshops, control towers and fuel storage facilities, as well as terminal buildings and parking.

If the airport is being built on soft ground, buildings may require piled foundations. Actual runways require good foundations; hardcore supporting the surface layers of concrete or tarmac needs to be heavily compacted. Plant used on airport construction is similar in scale and type to that used in major highway projects, except that it is concentrated within a limited area rather than over the many miles of a highway.

Airport maintenance is a particularly difficult type of work where resurfacing the runways has to be integrated with continuing operation of the airport. Usually the contractor is allowed an agreed number of hours during the night when he or she can work on a runway that is temporarily taken out of use. All the contractor’s plant, materials and workforce have to be marshalled off the runways, prepared to move immediately to the work site at the agreed start time. The contractor must finish his or her work and get off the runways again at the agreed time when flights may resume. Whilst working on the runway, the contractor must not impede or otherwise endanger aircraft movement on other runways.

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Improving Occupational Health and Safety

Construction companies are increasingly adopting the quality management systems spelled out by the International Organization for Standardization (ISO), such as the ISO 9000 series and the subsequent regulations that have been based on it. Although no recommendations on occupational health and safety are specified in this set of standards, there are cogent reasons for including preventive measures when implementing a management system such as that required by the ISO 9000.

Occupational health and safety regulations are written and implemented and are continuously being adapted to technological progress as well as to new safety techniques and to advances in occupational medicine. All too often, however, they are not followed, either deliberately or out of ignorance. When this occurs, models for safety management, such as the ISO 9000 series, assist in integrating the structure and content of preventive measures into management. The advantages of such a comprehensive approach are obvious.

Integrated management means that occupational health and safety regulations are no longer looked at in isolation, but gain relevance from the corresponding sections of a quality management handbook, as well as in process and work instructions, thus creating a fully integrated system. This integral approach can improve the chances of greater attention to accident prevention measures in daily construction practice and, thereby, reduce the number of workplace accidents and injuries. Dissemination of a handbook that integrates occupational health and safety procedures into the processes it describes is crucial for this process.

New management methods are aimed at putting people closer to the centre of the processes. Co-workers are being more actively involved. Information, communication and cooperation are promoted across hierarchical barriers. The reduction of absences due to illness or workplace accidents enhances the implementation of the principles of quality management in construction.

With the development of new building methods and equipment, safety requirements increase steadily in number. The increasing concern with environmental protection makes the problem even more complex. Coping with the demands of modern prevention is difficult without appropriate regulations and a centrally directed articulation of the process and work instructions. Clear divisions of responsibility and effective coordination for the prevention plan should, therefore, be written into the quality management system.

Improving Competitiveness

Documentation of the existence of an occupational safety management system is increasingly required when contractors submit bids for work, and its effectiveness has become one of the criteria for awarding a contract.

The pressure of international competition could become even greater in the future. It seems prudent, therefore, to integrate preventive measures into the quality management system now, rather than waiting and being forced by increasing competitive pressure to do so later, when the pressure of time and the costs of personnel and financing will be much greater. Furthermore, a not inconsiderable benefit of an integrated prevention/quality management system is that having such a well-documented programme in place is likely to reduce the costs of coverage, not only for workers’ compensation, but also for product liability.

Company Management

Company management must be committed to the integration of occupational health and safety into the management system. Goals specifying the content and time-frame of this effort should be defined and included in the basic statement of company policy. The necessary resources should be made available and appropriate personnel assigned to accomplish the project goals. Specialized safety personnel are generally required in large and mid-sized construction companies. In smaller companies, the employer must take the responsibility for the preventive aspects of the quality management system.

A periodic company management review closes the circle. The collective experiences in utilizing the integrated prevention/ quality management system should be examined and assessed, and plans for revision and for subsequent review should be formulated by company management.

Assessing Results

Assessment of results of the occupational safety management system that has been instituted is the second step in the integration of preventive measures and quality management.

The dates, kinds, frequency, causes and costs of accidents should be compiled, analysed and shared with all those in the company with relevant responsibilities. Such an analysis enables the company to set priorities in formulating or modifying process and work instructions. It also makes clear the extent to which occupational health and safety experience affects all divisions and all processes in the construction company. For this reason, defining the interface between company processes and preventive aspects takes on great importance. During bid preparation, the resources in time and money needed for comprehensive preventive measures, such as those incurred in clearing debris, can be precisely calculated.

When purchasing construction materials, attention should be paid to the availability of substitutes for potentially dangerous materials. From the beginning of a project responsibility for occupational health and safety should be assigned for particular aspects and each phase of the construction project. The need and availability for special training in occupational health and safety as well as the relative risks of injury and disease should be compelling considerations in the adoption of particular construction processes. These conditions must be recognized early on so that appropriately qualified workers can be selected and the courses of instruction can be arranged in a timely manner.

The responsibilities and authorities of the personnel assigned to safety and how they fit into the daily work should be documented in writing and collated with the onsite task descriptions. The construction company’s occupational safety staff should appear shown in its organizational chart, which, along with a clear responsibility matrix and schematic flow-charts of processes, should appear in the quality management handbook.

An Example from Germany

In practice, there are four formal procedures and their combinations for integrating occupational health and safety into a quality management system that have been implemented in Germany:

1. A quality management handbook and a separate occupational safety management handbook are developed. Each has its own procedures and work instructions. In extreme cases, this creates ineffective, insular organizational solutions, which require twice the amount of work and in practice do not accomplish the desired results.
2. An additional section is inserted into the quality management handbook with the heading “Occupational health and safety”. All statements on occupational health and safety are organized in this section. This path is chosen by some construction companies. Positioning a health and safety problem in a separate section may well highlight the importance of prevention, but it entails the risk being ignored as a “fifth wheel” and serves more as an evidence of intent rather than a command for appropriate action.
3. All aspects of occupational health and safety are worked directly into the quality management system. This is the most systematic implementation of the basic idea of integration. The integrated and flexible structuring of the presentation models of the German DIN EN ISO 9001-9003 permits such an inclusion.
4. The Underground Construction Trade Organization (Berufs-genossenschaft) favours a modular integration. This concept is explained below.

Integration in Quality Management

Once the assessment is completed, at the latest, those responsible for the construction project should contact the quality management officers and decide on the steps for actually integrating occupational safety into the management system. Comprehensive preparatory work should facilitate setting common priorities during the work that promise the greatest preventive results.

The demands of prevention that come out of the assessment are first divided into those that can be categorized according to the processes specific to the company and those that should be considered separately since they are more widespread, more comprehensive or of such a special character that they demand separate consideration. The following question can be of assistance in this categorization: Where would the interested reader of the handbook (e.g., the “customer” or the worker) most likely look for the relevant preventive policy, the section of a chapter devoted to a process specific to the company, or in a special section on occupational health and safety? Thus, it appears, a specialized procedural instruction on transporting hazardous materials would make the most sense in almost all construction companies if it were included in section on handling, storing, packing, conserving and shipping.

Coordination and Implementation

After this formal categorization should come linguistic coordination to ensure easy readability (this means presentation in the appropriate language(s) and in terms easily understood by individuals with educational levels characteristic of the particular workforce). Finally, the final documents must be formally endorsed by the top management of the company. At this juncture, it would be useful to publicize the significance of the changed or newly-implemented procedures and work instructions in company bulletins, safety circles, memos and any other available media, and to promote their application.

General Audits

To assess the effectiveness of the instructions, appropriate questions may be prepared for inclusion into general audits. In this manner, the coherence of work processes and occupational health and safety considerations is made unmistakably clear to the worker. Experience has shown that workers may at first be surprised when an audit team on the construction site in their particular division routinely asks questions on accident prevention as a matter of course. The consequent increase in the attention paid to safety and health by the workforce confirms the value of the integration of prevention into the quality management programme.

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Diversity of Projects and Work Activities

Many people outside the construction industry are unaware of the diversity and degree of specialization of work undertaken by the industry, though they see portions of it every day. In addition to traffic delays caused by encroachments on roads and street excavations, the public is frequently exposed to buildings being erected, subdivisions being constructed and, occasionally, to the demolition of structures. What is hidden away from view, in most cases, is the large amount of specialized work done either as part of a “new” construction project or as part of the ongoing repairs maintenance associated with almost anything constructed in the past.

The list of activities is very diverse, ranging from electrical, plumbing, heating and ventilating, painting, roofing and flooring work to very specialized work such as installing or repairing overhead doors, setting heavy machinery, applying fireproofing, refrigeration work and installing or testing communications systems.

The value of construction can be partially measured by the value of building permits. Table 1 shows the value of construction in Canada in 1993.

Table 1.  Value of construction projects in Canada, 1993 (based on value of building permits issued in 1993).

Source: Statistics Canada 1993.

The health and safety aspects of the work depend in large measure on the nature of the project. Each type of project and each work activity presents different hazards and solutions. Often, the severity, scope or size of the problem is related to the size of the project as well.

Client-Contractor Relationships

Clients are the individuals, partnerships, corporations or public authorities for whom construction is carried out. The vast majority of construction is done under contractual arrangements between clients and contractors. A client may select a contractor based on past performance or through an agent such as an architect or engineer. In other cases, it may decide to offer the project through advertising and tendering. The methods used and the client’s own attitude to health and safety can have a profound effect on the project’s health and safety performance.

For example, if a client chooses to “pre-qualify” contractors to ensure that they meet certain criteria, then this process excludes inexperienced contractors, those who may not have had satisfactory performance and those without qualified personnel required for the project. While health and safety performance has not previously been one of the common qualifications sought or considered by clients, it is gaining in usage, primarily with large industrial clients and with government agencies that purchase construction services.

Some clients promote safety much more than others. In some cases, this is due to the risk of damage to their existing facilities when contractors are brought in to perform maintenance or to expand the client’s facilities. Petrochemical companies in particular make it clear that contractor safety performance is a key condition of the contract.

Conversely, those firms who choose to offer their project through an unqualified open bidding process to obtain the lowest price often end up with contractors that may be unqualified to perform the work or who take short cuts to save on time and materials. This can have an adverse effect on health and safety performance.

Contractor-Contractor Relationships

Many people who are not familiar with the nature of the contractual arrangements common in construction presume that one contractor performs all or at least the major part of most building construction. For example, if a new office tower, sports complex or other high-visibility project is being constructed, the general contractor usually erects signs and often company flags to indicate its presence and to create the impression that this is “its project”. Years ago, this impression may have been relatively accurate, since some general contractors actually undertook to perform substantial parts of the project with their own direct-hire forces. However, since the mid-1970s, many, if not most, general contractors have assumed more of a project management role on large projects, with the vast majority of the work contracted out to a network of subcontractors, each of which has special skills in a particular aspect of the project. (See table 2)

Table 2. Contractors/subcontractors on typical industrial/commercial/institutional projects

The influence that this network of contractors may have on health and safety becomes fairly obvious when it is compared with a fixed worksite such as a factory or a mill. At a typical fixed-industry workplace, there is only one management entity, the employer. The employer has sole responsibility for the workplace, the lines of command and communication are simple and direct, and only one corporate philosophy applies. At a construction project, there may be ten or more employer entities (representing the general contractor and the usual subcontractors), and the lines of communication and authority tend to be more complex, indirect and often confused.

The attention given to health and safety by the person or company in charge can influence the health and safety performance of others. If the general contractor has attached a high degree of importance to health and safety, this can have a positive influence on the health and safety performance of the subcontractors on the project. The converse is also true.

Additionally, the overall health and safety performance of the site can be adversely affected by the performance of one subcontractor (e.g., if one subcontractor has poor housekeeping, leaving a mess behind as his or her forces move through the project, it can create problems for all of the other subcontractors onsite).

Regulatory efforts regarding health and safety are generally more difficult to introduce and administer in these multi-employer workplaces. It may be difficult to determine which employer has responsibility for which hazards or solutions, and any administrative controls which appear to be eminently workable in a single-employer workplace may need significant modification to be workable on a multi-employer construction project. For example, information regarding hazardous materials used on a construction project must be communicated to those who work with or near the materials, and workers must be adequately trained. At a fixed workplace with only one employer, all of the material and the information accompanying it is much more readily obtained, controlled and communicated, whereas on a construction project, any of the various subcontractors may be bringing in hazardous materials of which the general contractor has no knowledge. Additionally, workers employed by one subcontractor using a certain material may have been trained, but the crew working for another subcontractor in the same area but doing something entirely different may know nothing about the material and yet could be as much at risk as those using the material directly.

Another factor which emerges regarding contractor-contractor relationships relates to the bidding process. A subcontractor who bids too low may take short-cuts that compromise health and safety. In these cases, the general contractor must ensure that subcontractors adhere to the standards, specifications and statutes pertaining to health and safety. It is not uncommon on projects where everyone has bid very low to observe continuing health and safety problems coupled with excessive passing of responsibility, until regulatory authorities step in to impose a solution.

A further problem relates to the scheduling of work and the impact this can have on health and safety. With several different subcontractors on the site at one time, competing interests may create problems. Each contractor wants to get his or her work done as quickly as possible. When two or more contractors want to occupy the same space, or when one has to perform work overhead of another, problems can occur. This is typically a much more common problem in construction than in fixed industry, where the main competing interests tend to involve only operations versus maintenance.

Employer-Employee Relationships

The several employers on a particular project may have somewhat different relationships with their employees than those common at most fixed industrial workplaces. For example, unionized workers at a manufacturing facility tend to belong to one union. When the employer needs additional workers, it interviews and hires them and the new employees join the union. Where there are former unionized workers on layoff, they are re-hired generally on a seniority basis.

In the unionized part of the construction industry, a completely different system is used. Employers form collective associations which then enter into agreements with building and construction trade unions. The majority of the non-salaried direct-hire employees in the industry work through their union. When, for example, a contractor needs five additional carpenters at a project, he or she would call the local Carpenters’ Union and place a request for five carpenters to show up for work at the project on a certain day. The union would notify the five members at the top of the employment list that they are to report to the project to work for the particular firm. Depending on the provisions of the collective agreement between the employers and the union, the contractor may be able to “name hire” or select some of these workers. If there are no union members available to fill the employment call, the employer may be able to hire temporary workers who would join the union, or the union may bring in skilled workers from other locals to help fill the demand.

In non-unionized situations, employers use different processes to obtain additional staff. Prior employment lists, local employment centres, word of mouth and advertising in local newspapers are the principal methods used.

It is not uncommon for workers to be employed by several different employers in the course of a year. The employment duration varies with the nature of the project and the amount of work to be done. This places a large administrative load on the construction contractors compared with their fixed-industry counterparts (e.g., recordkeeping for income taxes, workers’ compensation, unemployment insurance, union dues, pensions, licensing and other regulatory or contractual issues).

This situation presents some unique challenges compared to the typical fixed-industry workplace. Training and qualifications must not only be standardized but portable from one job or sector to another. These important issues affect the construction industry much more profoundly than fixed industries. Construction employers expect workers to come to the project with certain skills and capabilities. In most trades, this is accomplished by a comprehensive apprenticeship programme. If a contractor places a call for five carpenters, he or she expects to see five qualified carpenters at the project on the day they are needed. If health and safety regulations require special training, the employer needs to be able to access a pool of workers with this training, since the training may not be readily available at the time the work is scheduled to start. An example of this is the Certified Worker Programme required at larger construction projects in Ontario, Canada, which involves having joint health and safety committees. Since this training is not currently part of the apprenticeship programme, alternative training systems had to be put in place to create a pool of trained workers.

With growing emphasis on specialized training or at least confirmation of skill level, training programmes conducted in conjunction with the building and construction trades unions will likely grow in importance, number and variety.

Inter-union Relationships

The structure of organized labour mirrors the way in which contractors have specialized within the industry. On a typical construction project, five or more trades may be represented onsite at any one time. This involves many of the same problems posed by multiple employers. Not only are there competing interests to deal with, but lines of authority and communication are more complex and sometimes blurred when compared with a single-employer, single-union workplace. This influences many aspects of health and safety. For example, which worker from which union will represent all workers on the project if there is a regulatory requirement for a health and safety representative? Who gets trained in what and by whom?

In the case of rehabilitation and reinstatement of injured workers, the options for skilled construction workers are much more limited than those of their fixed-industry counterparts. For example, an injured worker at a factory may be able to return to some other job at that workplace without crossing important jurisdictional boundaries between one union and another, because there is typically only one union in the factory. In construction, each trade has fairly clearly defined jurisdiction over the types of work its members can perform. This greatly limits the options for injured workers who may not be able to perform their normal pre-injury job functions but could none the less perform some other related work at that workplace.

Occasionally, jurisdictional disputes arise over which union should perform certain types of work which have health and safety implications. Examples include scaffold erection, boom truck operation, asbestos removal and rigging. Regulations in these areas need to consider jurisdictional concerns, especially with respect to licensing and training.

The Dynamic Nature of Construction

Construction workplaces are in many respects quite different from fixed industry. Not only are they different, they tend to be constantly changing. Unlike a factory which operates at a given location day after day, with the same equipment, the same workers, the same processes and generally the same conditions, construction projects evolve and change from day to day. Walls are erected, new workers from different trades arrive, materials change, employers change as they complete their portions of the work, and most projects are affected to some degree just by the changes in the weather.

When one project is completed, workers and employers move on to other projects to start all over again. This indicates the dynamic nature of the industry. Some employers work in several different cities, provinces, states or even countries. Similarly, many skilled construction workers move with the work. These factors influence many aspects of health and safety, including workers’ compensation, health and safety regulations, performance measurement and training.

Summary

The construction industry is presented with some very different conditions from those in fixed industry. These conditions must be considered when control strategies are being contemplated and may help to explain why things are done differently in the construction industry. Solutions developed with the input from both construction labour and construction management, who know these conditions and how to deal effectively with them, offer the best chance for improving health and safety performance.

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