Does Air Pollution Shorten Lives?

The cause of a disease is often difficult to establish. For chronic diseases, establishing a cause and effect relationship is especially difficult. Many studies show that populations exposed to urban air pollution have a shorter life expectancy and higher incidence of lung cancer, emphysema, and other chronic respiratory diseases . Yet it is a long step to assert that this observed association between air pollution and ill health is proof that air pollution causes ill health and that steps ought to be taken to abate air pollution for public health reasons. There is disagreement among physicians as to whether air pollution causes lung cancer, bronchitis, or emphysema, or generally reduces life expectancy . A related argument is that the effect of air pollution is so slight that it is not a matter of public concern .