Historically, environmental health concerns have focused on toxicological and microbiological risks to health from local exposures, such as air pollution or contaminated waters. The scale of environmental health problems has expanded from household (e.g. indoor air pollution), to neighbourhood (e.g., domestic wastes) to city (e.g. urban air pollution) to region (e.g. transboundary contamination), and now to global level (e.g. climate change). Large-scale environmental hazards to human health  include global climate change, the health risks posed by stratospheric ozone depletion, loss of biodiversity, changes in hydrological systems and the supplies of freshwater, land degradation and stresses on food-producing systems (see figure). Appreciation of this scale and type of influence on human health requires a new perspective which focuses on ecosystems and on the recognition that the foundations of long-term good health in populations relies in great part on the continued stability and functioning of the biosphere's life-supporting systems. It also brings an appreciation of the complexity of the systems upon which we depend.

This is a World Health Organization publication.  Date not noted on publication.