Regional anomalies in chronic obstructive pulmonary disease; comparison with acid air pollution particulate characteristics

Abstract

Mortality rates due to chronic obstructive pulmonary disease (COPD) for males and females in standard metropolitan statistical areas are highest in two broad regions of the U.S. One is the southeast, with age-adjusted rates high in Georgia and north Florida but decreasing toward south Florida; the other is the western plains, with rates high in Colorado and north Texas but decreasing toward south Texas. Rates are generally low in the northeast, upper midwest, and far west, as well as in the largest cities of these regions. These geographic patterns suggest that atmospheric environmental conditions may contribute to the risk of COPD. Based on measured aerosol characteristics and atmospheric chemical reasoning, it is argued that ambient air in the high COPD regions may be especially irritating to the respiratory tract because of fine particles that contain the reaction products of acid air pollutants. In the southeast, sulfuric acid aerosol concentrations are high, apparently because of a sunny warm humid climate that favors rapid oxidation of sulfur dioxide as well as the region's proximity to large primary air pollution sources further north. Particulate sulfur is also associated with soil mineral constituents. In the western plains, concentrations of alkaline dust are high because of soil erosion during windy dry conditions. Acid air pollutants can be scavenged to mineral particle surfaces and form chemical reaction products that may include solubilized mineral aluminum. These may be inhaled and deposited in the respiratory tract so as to contribute to COPD mortality risk.