Problems in the Assessment of Lung Cancer Risk Posed by Ambient Air Pollutants

Abstract

There is some controversy regarding the contribution of ambient air pollution to lung cancer risk. The estimates range from too small to quantify to a few percent of the total number of lung cancer deaths for the U.S. and U.K. However, even with this controversy, these figures agree that the risk due to ambient air pollution is not great (1, 4, 9, 15, 17, 19). The estimate is thought to be obscured or to involve uncertainty because of the overwhelming contribution to lung cancer mortality by cigarette smoking, associated variations in smoking habits, and changes in the tar and nicotine content of cigarettes. We must also realize that the quality of ambient air has been changing over the past 20 years, at least as evidenced by measures of certain specific indicator pollutants (Figure 1), presumably due to decreases in coal use as a heating source and regulations on open burning (6). Thus, the risk of incurring lung cancer due to general air pollution may not be constant.