The support of human life is one of the basic services provided by the environment. Changes in the life support capacity of the environment brought about by, for example, pollution of the air or water can lead to increases in the incidence of disease, impairment of daily activities, and perhaps reduction of life expectancy. Human alteration of the environment can affect health through a number of channels, including:

organic compounds, which may contaminate aquifers used as sources of drinking water;

poorly treated sewage or septic tank leachate, which may spread disease-causing bacteria and viruses into drinking water supplies and among shellfish bound for human consumption;

elevated levels of particulate matter air pollution, which can increase the risk of premature mortality;

air emissions from manufacturing facilities, auto body repair and painting shops, and the like, which may include carcinogens; and

climate change induced by greenhouse gas emissions that can cause increased periods of heat and associated heat-related illness and premature mortality.