Coarse Particulate Matter Air Pollution and Hospital Admissions for Cardiovascular and Respiratory Diseases Among Medicare Patients

Abstract

Regulatory control of airborne particulate matter is hindered by an uncertain understanding of the toxicity of the particulate matter mixture. The National Research Council's Committee on Research Priorities for Airborne Particulate Matter identified the limited information on the health effects of particulate matter characteristics, including size, as a key area for research.¹ Numerous epidemiological studies have been published on risks associated with particulate matter that is 10 μm or less in diameter (PM₁₀).² More recent work has focused on particulate matter that is 2.5 μm or less in diameter (PM_2.5), for which strong evidence of an association with mortality and morbidity has been found.^3,4 Research on the health effects of coarse thoracic particles in the size range of greater than 2.5 μm and 10 μm or less in diameter (PM_10-2.5) is limited and findings have been mixed.⁵ The chemical composition of particulate matter differs by size with more crustal materials in PM_10-2.5 and more combustion-related constituents in PM_2.5.^6-8 The health effects associated with ambient exposure to PM_10-2.5 could differ from those of PM_2.5 given differences in the sites of deposition in the respiratory tract and the sources and chemical composition for these 2 different-sized fractions.