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If you want to learn about the health of a population, look at the air they breathe, the water they drink, and the places where they live.

Hippocrates, Fifth century BCE

This chapter looks beyond the individual patient and clinician to the behaviors of human populations and their impact on the environment, which itself exerts a profound influence on human health and illness. We will discuss opportunities and strategies for modifying those behaviors—on the individual and societal scale—that affect human health and well-being.

The attention of health professionals to environmental factors is warranted by developments in our scientific understanding of three interrelated domains: (1) the impact of environmental degradation and enhancement on human health, (2) the impact of human behavior on the environment, and (3) the effectiveness of initiatives to modify human behavior on a population scale. This chapter will review each of these domains and conclude with suggestions for clinicians to draw upon this information in the care of patients and to become engaged in the process of societal behavior change for the well-being of the planet.


As Hippocrates observed millennia ago, the quality of the biosphere that supports us has a marked impact on our health. Disease burdens due to environmental degradation include altered fertility rates, challenges to the health of newborns, disorders of human development, malnutrition, vector patterns of infectious diseases, skin cancers due to ultraviolet radiation exposure, respiratory disorders, and obesity. Understanding connections between environmental change and these kinds of health problems has increased as agencies such as the World Health Organization (WHO), U.S. National Institutes of Health (NIH), U.S. Centers for Disease Control and Prevention (CDC), Institute of Medicine (IOM), and others have compiled research on the environment–health connection. A few of these connections are summarized here.

Air Pollution

The WHO estimates that there are 7 million deaths worldwide each year from air pollutants—over five times the number of traffic fatalities. Globally, 9 out of 10 people breathe polluted air. Over an 18-year period, increased death rates from dementias have been linked to a rise in the concentration of pesticides, industrial effluents, car exhaust, and other pollutants in the environment. Sulfur dioxide, produced by combustion of fossil fuels, has been shown to induce acute bronchoconstriction in asthmatics. Particulate air pollution has been implicated in respiratory ailments and in derangement of heart rate variability, a risk factor for cardiac events. Carbon monoxide (CO), primarily emitted from internal combustion engines in motor vehicles, has serious health effects in high concentrations leading to carbon monoxide poisoning. More frequently, however, lower-level exposures to CO may increase platelet activity and coagulation, leading to increased risks of thromboembolism. A global meta-analysis found an association between ...

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