Exposure to coarse air pollution not associated with hospital admission for respiratory diseases

Exposure to coarse particulate matter air pollution such as from agricultural activities, windblown dust and mechanical grinding is not statistically significantly associated with emergency hospital admissions for respiratory and cardiovascular diseases among Medicare patients, according to a study in the May 14 issue of JAMA.

Health risks of fine particulate matter of 2.5 µm or less in aerodynamic diameter (PM2.5) have been studied extensively over the last decade, and there is strong evidence of an association for a higher risk of illness and death. Evidence concerning the health risks of the coarse particulate matter of greater than 2.5 µm and 10 µm or less in aerodynamic diameter (PM10-2.5) is limited, and findings have been mixed, according to background information in the article. Coarse particles would likely deposit in the upper and larger airways. Particles in the PM2.5 size range, which are more likely to result from combustion processes, can reach the smaller airways and air sacs within the lungs.

Roger D. Peng, Ph.D., of the Johns Hopkins Bloomberg School of Public Health, Baltimore, and colleagues estimated the risk of hospital admissions for cardiovascular and respiratory diseases associated with PM10-2.5 exposure. The researchers used a database assembled for 108 U.S. counties (population larger than 200,000 in 2000) with daily cardiovascular and respiratory disease admission rates, temperature and dew-point temperature and monitoring of PM10-2.5 and PM2.5 concentrations. Admission rates were constructed from the Medicare National Claims History Files, for a study population of approximately 12 million Medicare enrollees living on average 9 miles from pairs of PM10 and PM2.5 monitors.