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Urbanization is a major feature of the contemporary world. At the beginning of the nineteenth century there were some 50 million people living in urban areas. By 1975 there were 1.6 billion, and by the year 2000 there will be 3.1 billion (Harpham, Lusty and Vaugham 1988). Such figures outstrip by far the growth of rural population.

However, the process of urbanization has often had hazardous impacts on the health of those who work and live in cities and towns. To a greater or lesser extent, the production of adequate housing, the provision of urban infrastructure and the control of traffic has not kept pace with the growth of urban population. This has generated a myriad of health problems.


Housing conditions throughout the world are far from adequate. For example, by the mid-1980s, 40 to 50% of the population in many cities in developing countries were living in substandard accommodations (WHO Commission on Health and Environment 1992b). Such figures have increased ever since. Although the situation in industrialized countries is less critical, housing problems such as decay, overcrowding and even homelessness are frequent.

The major aspects of the residential environment which influence health, and their associated hazards, are presented in table 1. The health of a worker is likely to be affected if his or her residence is deficient in one or more of these aspects. In developing countries, for instance, some 600 million urban dwellers live in health- and life-threatening homes and neighbourhoods (Hardoy, Cairncross and Satterthwaite 1990; WHO 1992b).

Table 1. Housing and health

Housing problems

Health hazards

Poor control of temperature

Heat stress, hypothermia

Poor control of ventilation
(when there is smoke from indoor fires)

Acute and chronic respiratory diseases

Poor control of dust



Household accidents, easier spread of
communicable diseases
(e.g., tuberculosis, influenza, meningitis)

Poor control of open fires, poor protection
against kerosene or bottled gas


Poor finishing of walls, floors or roofs
(allowing the access of vectors)

Chagas’ disease, plague, typhus, shigellosis,
hepatitis, poliomyelitis, legionnaire’s disease,
relapsing fever, house dust allergy

Siting of house
(close to vector breeding areas)

Malaria, schistosomiasis, filariasis,

Siting of house

(in area prone to disasters such as landslides
or floodings)


Construction defects


Source: Hardoy et al. 1990; Harpham et al. 1988; WHO Commission on Health and Environment 1992b.

Housing problems may also have a direct effect on occupational health, in the case of those who work in residential environments. Those include domestic servants and also a growing number of small-scale producers in a variety of cottage industries. These producers may be further affected when their production processes generate some form of pollution. Selected studies in these types of industries have detected hazardous wastes with consequences such as cardiovascular diseases, skin cancer, neurological disorders, bronchial cancer, photophobia and infant methaemoglobinaemia (Hamza 1991).

Prevention of home-related problems includes action in different stages of housing provision:

  1. location (e.g., safe and vector-free sites)
  2. house design (e.g., spaces with adequate size and climatic protection, use of non-perishable building materials, adequate protection for equipment)
  3. construction (prevention of construction defects)
  4. maintenance (e.g., proper control of equipment, proper screening).


The insertion of industrial activities in the residential environment may require special measures of protection, according to the particular process of production.

The specific housing solutions may vary widely from place to place, depending on the social, economic, technical and cultural circumstances. A great number of cities and towns do have local planning and building legislation that includes measures to prevent health hazards. However, such legislation is often not enforced due to ignorance, lack of legal control or, in most cases, lack of financial resources to build proper housing. Therefore, it is important not only to design (and update) adequate codes, but also to create the conditions for their implementation.

Urban Infrastructure: The Provision of Environmental Health Services

Housing may also affect health when it is not properly supplied with environmental health services such as garbage collection, water, sanitation and drainage. The inadequate provision of these services, however, extend beyond the housing realm, and may cause hazards for the city or town as a whole. Standards of provision of these services are still critical in a large number of places. For example, 30 to 50% of solid waste generated within urban centres is left uncollected. In 1985 there were 100 million more people without water service than in 1975. More than two billion people still have no sanitary means to dispose of human waste (Hardoy, Cairncross and Satterthwaite 1990; WHO Commission on Health and Environment 1992b). And the media have frequently shown cases of floods and other accidents connected to inadequate urban drainage.

Hazards derived from deficient provision of environmental health services are presented in table 2. Cross-service hazards are also common—e.g., contamination of water supply due to lack of sanitation, dissemination of refuse through non-drained water. To give one illustration of the extent of infrastructural problems among many, a child is killed worldwide every 20 seconds due to diarrhoea—which is a major outcome of deficient environmental health services.

Table 2. Urban infrastructure and health

Problems in the provision of
environmental health services

Health hazards

Uncollected garbage

Pathogens in the refuse, disease vectors (mainly flies and rats) which breed or feed in the refuse, fire hazards, pollution of water flows

Deficiency in quantity and/or
quality of water

Diarrhoea, trachoma, infectious skin diseases, infections carried out by body lice, other diseases originated by consumption of non-washed food

Lack of sanitation

Faeco-oral infections (e.g., diarrhoea, cholera, typhoid fever), intestinal parasites, filariasis

Lack of drainage

Accidents (from floods, landslides, collapsing houses), faeco-oral infections, schistosomiasis, mosquito-borne diseases (e.g., malaria, dengue, yellow fever), Bancroftian filariasis

Source: Hardoy et al. 1990; WHO Commission on Health and Environment 1992b.

Those labourers whose immediate or wider working environment is not adequately supplied with such services are exposed to a profusion of occupational health risks. Those who work in the provision or maintenance of services, such as garbage pickers, sweepers and scavengers, are further exposed.

There exist indeed technical solutions capable of ameliorating the provision of environmental health services. They encompass, among many others, garbage recycling schemes (including support to scavengers), use of different kinds of garbage collection vehicles to reach different types of roads (including those of informal settlements), water-saving fittings, tighter control of water leakages and low-cost sanitation schemes such as ventilated pit latrines, septic tanks or small-bore sewers.

However, the success of each solution will depend on its appropriateness to the local circumstances and on the local resources and capacity to implement it. Political willingness is fundamental, but not enough. Governments have frequently found it difficult to provide urban services adequately by themselves. Success stories of good supply have often included cooperation between the public, private and/or voluntary sectors. A thorough involvement and support of the local communities is important. This often requires official recognition of the large number of illegal and semi-legal settlements (especially but not only in developing countries), which bear a heavy part of the environmental health problems. Workers directly involved in services such as garbage collection or recycling and sewerage maintenance need special equipment for protection, such as gloves, overalls and masks.


Cities and towns have depended heavily on ground transport for the movement of people and goods. Thus, the increase in urbanization throughout the world has been accompanied by a sharp growth in urban traffic. However, such a situation has generated a large number of accidents. Some 500,000 people are killed in traffic accidents each year, two-thirds of which occur in urban or peri-urban areas. In addition, according to many studies in different countries, for every death there are ten to twenty persons injured. Many cases suffer permanent or prolonged loss of productivity (Urban Edge 1990a; WHO Commission on Health and Environment 1992a). A large share of such data relates to people on their way to or from work—and such a type of traffic accident has lately been considered an occupational hazard.

According to World Bank studies, the main causes of urban traffic accidents include: poor condition of vehicles; deteriorated streets; different types of traffic—from pedestrians and animals to trucks—sharing the same streets or lanes; non-existent foot-paths; and reckless road behaviour (both from drivers and pedestrians) (Urban Edge 1990a, 1990b).

A further hazard generated by the expansion of urban traffic is air and noise pollution. Health problems include acute and chronic respiratory diseases, malignancies and hearing deficiencies (pollution is also dealt with in other articles in this Encyclopaedia).

Technical solutions to ameliorate road and car safety (as well as pollution) abound. The major challenge seems to be changing the attitudes of drivers, pedestrians and public officials. Road safety education—from elementary school teaching to campaigns throughout the media—has often been recommended as a policy to target drivers and/or pedestrians (and such programmes have often had some degree of success when implemented). Public officials have the responsibility to design and enforce traffic legislation, inspect vehicles and design and implement engineering safety measures. However, according to the aforementioned studies, these officials seldom perceive traffic accidents (or pollution) as a top priority, or have the means to act dutifully (Urban Edge 1990a, 1990b). Therefore, they have to be targeted by educational campaigns, and supported in their work.

The Urban Fabric

In addition to the specific issues already noted (housing, services, traffic), the overall growth of the urban fabric also has had an impact on health. Firstly, urban areas are usually dense, a fact which facilitates the spread of communicable diseases. Secondly, such areas concentrate a large number of industries, and their associated pollution. Thirdly, through the process of urban growth, natural foci of disease vectors may get entrapped within new urban areas, and new niches for disease vectors may be established. Vectors may adapt to new (urban) habitats—for example, those responsible for urban malaria, dengue and yellow fever. Fourthly, urbanization has often had psychosocial consequences such as stress, alienation, instability and insecurity; which, in their turn, have led to problems such as depression and alcohol and drug abuse (Harpham, Lusty and Vaugham 1988; WHO Commission on Health and Environment 1992a).

Past experiences have demonstrated the possibility (and the need) to tackle health problems via improvements in urbanization. For instance, “¼ the remarkable decline in mortality rates and improvements in health in Europe and North America at the turn of the last century owe more to improved nutrition and improvements in water supply, sanitation and other aspects of housing and living conditions than to medical establishments” (Hardoy, Cairncross and Satterthwaite 1990).

Solutions for the mounting problems of urbanization need sound integration between (often separated) urban planning and management, and the participation of the different public, private and voluntary actors which operate in the urban arena. Urbanization affects a wide range of workers. Contrary to other sources or types of health problems (which might affect specific categories of workers), occupational hazards derived from urbanization cannot be dealt with through single trade union action or pressure. They require inter-profession action, or, even more broadly, action from the urban community in general.



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Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides