They fall sick for two main reasons. The first is a lack of essential environmental resources – chief among them sufficient and clean water, food, shelter, fuel, and air.
Air pollution over Mexico City
© Julio Etchart/Reportage/Still Pictures
People also become ill through exposure to hazards in the environment. Many diseases are linked to environmental problems such as polluted drinking water, poor waste disposal and air and exposure to mosquitoes and other carriers of disease. Some pollutants, such as pesticides, traffic emissions and industrial solvents, are created by human activities. Others, including arsenic or ultraviolet radiation, occur naturally in the environment, although exposure can be made worse by human activities.
These pollutants can undermine health in various ways, by causing diseases such as bronchitis or asthma, contributing to cancer or birth defects or perhaps by damaging the body's immune system, which makes people more susceptible to a variety of other health risks.
But changes in the way people live and work can also cause a sudden increase in old diseases or the emergence of new ones. Overcrowding and industrialisation affect the health of millions in the developing world. The emergence of some 30 new diseases in the past 20 years, including HIV, Ebola and haemorrhagic illnesses, has become a growing public health issue. Tobacco now kills over 11,000 people a day worldwide.
Rapid or persistent population growth is one of the major driving forces acting on environmental health. It can result in severe environmental damage, and increased pressures on local infrastructure and services. It has a direct impact on air pollution, on access to basic sanitation, safe drinking water and an adequate and safe food supply. It also fuels the rate of urbanisation, often leading to slum settlements and shanty towns.
As the global population continues to grow, there is increasing pressure to develop agriculture, roads and transport systems in previously unsettled areas. This land conversion can encourage the spread of diseases. For example, leishmaniasis, an infectious disease transmitted through a sandfly bite, has increased to 12 million cases each year alongside land development in Africa, Latin America and West Asia. The incidence of mosquito-borne dengue has also increased, and forest clearance is associated with a higher incidence of diseases such as malaria.
Poverty also influences health because it largely determines an individual's environmental risks, as well as access to resources to deal with those risks. Many in the poorest countries live in situations that imperil their health through steady exposure to biological pathogens in the immediate environment. More than 1 billion people in developing countries live without adequate shelter or in unacceptable housing, more than 1 billion lack access to safe water, and some 2.4 billion people have no access to adequate sanitation – all of which are essential for good health. Unable to afford clean fuels or efficient stoves, the poor rely instead on smoky biomass fuels for cooking and heating.
In developing countries, the poorest people are often excluded from the benefits of emerging prosperity and may also face a disproportionate share of health risks related to economic growth. Urban slums may be located near major roads, factories, or dumpsites, for instance, exposing residents to higher levels of air pollution or to the risks of industrial accidents. Even in wealthier countries where environmental threats to the general population may be relatively small, they are likely to be greater for poor and minority populations.
But prosperity can also generate environmental health problems. Global energy use, which has increased nearly 70 per cent since 1971, is projected to increase at more than 2 per cent annually for the next 15 years. This increase will raise greenhouse gas emissions about 50 per cent higher than current levels, unless a concerted effort takes place to increase energy efficiency and move away from today's heavy reliance on fossil fuels. Industrial and agricultural pollutants will also increase if the global economy expands, as expected, four- or five-fold over the next 50 years – unless new approaches to sustainable production are found.
WHO - Protection of the Human Environment.
© People & the Planet 2000 - 2006