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close this bookInitial Environmental Assessment: Urban Development - Series no 12 (NORAD, 1996)
close this folderPart I: Urban development. The urban environment, projects and environmental impacts.
close this folder3 Possible environmental impacts
View the document(introduction...)
View the document3.1 Air, water and soil
View the document3.2 Vegetation, fauna and ecosystems
View the document3.3 Management of natural resources
View the document3.4 Climate
View the document3.5 Landscape, architecture and cultural heritage
View the document3.6 Health
View the document3.7 Way of life

3.6 Health

The quality of people's living conditions is decided by health, labour conditions, economy, education, social relations, housing and neighbourhood environment. Health is considered the most important of these factors. Poor health can seldom be compensated and usually has consequences for the other factors. The concept of health covers two main components; physical and mental health, which mutually affect each other. The broad definition of health defined by the World Health Organisation (WHO) gives the basis for this discussion of health impacts. WHO defines good health as a condition of perfect physical, mental and social well-being and ability to function, and not just an absence of disease.

The physical environment of urban areas can affect health directly, for instance through noise and pollution. Other aspects of the physical environment have indirect impacts. The possibilities for social contact in the neighbourhood may be affected by how the surroundings are designed and organised, and social networks are again important for physical and mental health. Physical planning and construction projects shape the physical environment and thereby influence the daily life and living conditions of people in ways which cause both positive and negative health impacts. Several environmental factors are affected, which in turn may impact health. These factors can be divided into three main groups; physical and chemical environmental factors (air, drinking water, noise, waste, light, radiation), psycho-social environmental factors, and accidents.

Polluted air can cause several types of diseases and injuries, ranging from minor irritation of mucous membranes to allergic reactions, respiratory diseases, asthma and chronic lung diseases, and cancer. Important outdoor pollutant substances are described in 3.1, but the indoor climate of houses, offices and factories can be polluted and hazardous to health. Poor indoor climates in modern buildings is a well-known phenomenon. Such buildings are often termed "sick houses". The causes may be additives in building materials, furniture, paint, carpets, etc. which release formaldehyde, heavy metals, organic solvents etc.. Buildings containing air condition facilities may trap these substances indoors causing concentrations to become health hazardous. Modern ventilation systems can spread substances, fungi etc. that are hazardous to health. Electrical facilities may result in noise and create extremely low frequency fields (ELF). Several symptoms and diseases may occur as a result of poor indoor climate. An overview of this problem area is given in Table 3 at the end of this booklet.

Polluted water may contain bacteria, virus, organisms and chemical substances which may be harmful to people (see 3.1 and booklet 7 "Water supply").

Noise may constitute a substantial health problem in urban areas. The most common sources are transport, technical installations, neighbours, construction activity, and recreational and cultural activity. The negative impacts are both physiological; like hearing impairment, changes to blood pressure, respiratory and digestive systems, social; like disturbances of communication and social life, and mental; like problems with sleep, tiredness, concentration problems and stress. Traffic noise and pollution is a large problem related to transport lines in urban areas. The problems are, however, not just a direct impact of construction of new roads, railways etc.. Changes to traffic currents can result in existing transport lines receiving increased traffic for shorter or longer periods. It is therefore not enough to consider local noise and pollution problems, but also which impacts the new transport line has on traffic in other areas. (More about noise in booklet 8 "Transport").

Low frequency electromagnetic fields (EMF) can be created by power transmission lines. Science has not yet agreed on to which extent EMF may cause biological reaction, but recent findings indicate it may be health damaging to live close to power transmission lines. The strength of both electrical and magnetic fields is reduced with distance from the power transmission lines.

The visual expression of physical environments creates reactions among people and may impact mental well-being and behaviour. The design, substance, colour and other characteristics of the surroundings induce moods, experiences and thoughts. The surroundings may induce alienation or a sense of belonging, disgust or pleasure, insecurity or security depending on the visual expression.

Studies have shown that a reliable social network is important for both mental and physical health. Weakening of social networks, which previously held people together, has been suggested as one of the explanations for increased urban crime, violence and mental instability (mental ailments, drug abuse). Rapidly growing settlements with few arenas for contact, recreation and common activity may contribute to lack of social integration (also see 3.7) The strengthening of existing social networks or establishment of new networks may prevent health injuries. The physical design of a settled area may be important and can be influenced. The design of for instance a housing area is decisive for how many natural meeting points that exist, and thereby how many possibilities people have to meet others through informal encounters or organised activities. Changes in neighbourhood conditions may require cooperation between various institutions, professionals and local population.

The number of injuries and accidents is of great significance when assessing the health status. The frequency of urban traffic accidents in developing countries is often higher than in many industrial countries. The causes may be increased traffic together with poor traffic training, lack of traffic separation, poor driving conditions, inadequate road marking, few traffic penalty measures, and poor vehicle standards. Health hazardous working environments, inadequate safety measures, and outmoded poorly maintained technology may cause many workers to suffer permanently reduced ability to work or that they become completely invalid. The localisation of settlements in the vicinity of industry, mining and extraction of sand and gravel, oilfields, garbage dumps, transport lines or areas which are especially vulnerable to natural hazards may result in accidents or be harmful to health.

Negative impacts of urban development may be reduced or avoided by securing that health and environmental considerations are present in physical planning, and that these form the basis for choice of materials and design of construction projects.

To avoid people being subjected to noise, radiation and polluted air from other activity the following should be secured prior to initiation of any construction project (for instance residential areas):

· that the project is located away from pollution sources,

- and where necessary ensure that buffer zones are present or that the project is located at an adequate distance from pollution sources,

- and/or establish measures to reduce pollution at the source.

· that the project is located away from areas with noise from roads, airports etc.,

- and where necessary implement noise reduction measures along transport lines and soundproofing of houses.

· that alternative locations have been properly assessed.

In order to avoid exposing inhabitants to natural hazards one should make sure that urban development is not located to or takes place in the following areas:

· flood plains, coastal zones and other areas vulnerable to floods,

· areas with unstable soil, or areas vulnerable to landslides,

· areas with especially saline soil,

· areas with seismic or volcanic activity,

· areas that are especially steep or humid, or

· areas with large amounts of contagious organisms.

If the urban development project cannot be moved to another location, the design must be adapted to the local conditions.

Several traffic safety measures may be relevant to avoid or reduce the extent of accidents and injuries. One distinguishes often between passive and active measures in connection with preventive efforts. Passive measures are often better prevention against accidents than active measures, which often require substantial personal action on the part of the individual. Examples of passive measures which can be included in physical planning are road safety measures, speed reducing bumps, separating pedestrians and cyclists from cars etc.. For optimum impact passive measures should be combined with training and awareness campaigns.

Conservation or establishment of areas for recreation and outdoor life may be relevant as preventive health measures. Green structures should be easily accessible and should not be separated from housing areas by barriers like for instance transport lines.

The type of physical design of settled areas which gives the best possible impacts with regard to environment and health may vary from case to case. One can distinguish between two main types of settlement; open and dense. An open settlement can be founded on light, air and green structures. These factors should be considered against the environmental impacts of more land requirement, increased transport needs, and possible complex neighbourhood conditions etc.. A dense settlement pattern uses less area, reduces need for transport, and may result in closer and more simple social networks in the neighbourhood. Dense urban areas have traditionally been connected with slum and health hazardous surroundings. Slum clearance and upgrading of such areas may however create safe living conditions both with regard to health and social conditions. Dependent on design and density of the settlement, densification can in several cases be a more environmentally sound urban development than scattered buildings entailing expansion over new areas.