The connections between environment, health and development are multiple and multidirectional. Perhaps most obviously, the environment can be seen in a negative sense as a source of threats or hazards to human health. Environment-related threats in developing countries tend to be manifestly more significant than in higher-income countries, especially those associated with infectious disease such as environmental contamination by human waste and proliferation of insect vectors. Environment-related threats may also be associated with development processes, such as increasing industrial pollution, use of agrochemicals, vehicle pollution, and urban expansion on to unstable hill-slopes.

But the environment also acts in a positive sense in provision of resources for health and wellbeing, providing nutrients for food crops, sources of wild food, water and oxygen, and a range of other ecological functions that help sustain healthy lives. Degradation of environmental resources in turn has consequences for human health that may include heightened risks of waterborne diseases, respiratory diseases and malnutrition. For both these forms of risk, the key question for the Network is how poverty and/or development mediates health outcomes, by shaping the hazard itself or the vulnerability of those exposed to its effects.

It is important also to recognize that the linkages can work in other ways too. Under conditions of poverty, the consequences of shifting disease burdens on livelihoods and family structures can in turn exacerbate environmental degradation. In a more positive sense, health status can function as a resource to help households cope with environmental change or environmental hazards. Though most research at the nexus between health, environment and development is likely to examine environment-to-health linkages, these are two examples in which research work has emphasized linkages operating in the reverse direction, with health as the start point.

Central importance of poverty

Poverty is not synonymous with vulnerability, but it is of central importance in heightening risk of health outcomes. Poverty influences the extent to which people are exposed to hazards in their occupations and at home. The urban poorest, for example, unable to access titles to land or better housing, are commonly concentrated in fragile dwellings in marginal locations, with inadequate sanitation and high levels of indoor pollution. Poverty shapes people’s ability to access adequate food and clean water, their ability to avoid or cope with health threats that arise, and their access to preventive and curative health care. The rural poor in water-stressed environments, for example, may find their livelihoods undermined by environmental degradation with few alternative options, combined with limited access to drinking water and remoteness from health facilities. Poverty also helps determine people’s health status, and hence their underlying susceptibility to new infections, injuries or mental health problems arising from environmental hazards.