Coarse particulate matter air pollution and hospital admissions for cardiovascular and respiratory diseases among Medicare patients

Roger D. Peng, PhD; Howard H. Chang, BS; Michelle L. Bell, PhD; Aidan McDermott, PhD; Scott L. Zeger, PhD; Jonathan M. Samet, MD; Francesca Dominici, PhD

JAMA. 2008;299(18):2172-2179.

Context  Health risks of fine particulate matter of 2.5 µm or less in aerodynamic diameter (PM_2.5) have been studied extensively over the last decade. Evidence concerning the health risks of the coarse fraction of greater than 2.5 µm and 10 µm or less in aerodynamic diameter (PM_10-2.5) is limited.

Objective  To estimate risk of hospital admissions for cardiovascular and respiratory diseases associated with PM_10-2.5 exposure, controlling for PM_2.5.

Design, Setting, and Participants  Using a database assembled for 108 US counties with daily cardiovascular and respiratory disease admission rates, temperature and dew-point temperature, and PM_10-2.5 and PM_2.5 concentrations were calculated with monitoring data as an exposure surrogate from January 1, 1999, through December 31, 2005. 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 (14.4 km) from collocated pairs of PM₁₀ and PM_2.5 monitors.

Main Outcome Measures  Daily counts of county-wide emergency hospital admissions for primary diagnoses of cardiovascular or respiratory disease.

Results  There were 3.7 million cardiovascular disease and 1.4 million respiratory disease admissions. A 10-µg/m³ increase in PM_10-2.5 was associated with a 0.36% (95% posterior interval PI], 0.05% to 0.68%) increase in cardiovascular disease admissions on the same day. However, when adjusted for PM_2.5, the association was no longer statistically significant (0.25%; 95% PI, –0.11% to 0.60%). A 10-µg/m³ increase in PM_10-2.5 was associated with a nonstatistically significant unadjusted 0.33% (95% PI, –0.21% to 0.86%) increase in respiratory disease admissions and with a 0.26% (95% PI, –0.32% to 0.84%) increase in respiratory disease admissions when adjusted for PM_2.5. The unadjusted associations of PM_2.5 with cardiovascular and respiratory disease admissions were 0.71% (95% PI, 0.45%-0.96%) for same-day exposure and 0.44% (95% PI, 0.06% to 0.82%) for exposure 2 days before hospital admission.

Conclusion  After adjustment for PM_2.5, there were no statistically significant associations between coarse particulates and hospital admissions for cardiovascular and respiratory diseases.