Wednesday, June 3, 2009

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A National Analysis

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A
National Analysis

Environmental Health Perspectives Volume 117, Number 6, June 2009

Antonella Zanobetti and Joel Schwartz
Department of Environmental Health, Harvard School of Public Health, Boston,
Massachusetts, USA


Background: Although many studies have examined the effects of air pollution
on mortality, data limitations have resulted in fewer studies of both
particulate matter with an aerodynamic diameter of ? 2.5 µm (PM2.5 ; fine
particles) and of coarse particles (particles with an aerodynamic diameter >
2.5 and < 10 µm ; PM coarse) . We conducted a national, multicity
time-series study of the acute effect of PM2.5 and PM coarse on the
increased risk of death for all causes, cardiovascular disease (CVD) ,
myocardial infarction (MI) , stroke, and respiratory mortality for the years

Method: We applied a city- and season-specific Poisson regression in 112
U.S. cities to examine the association of mean (day of death and previous
day) PM2.5 and PM coarse with daily deaths. We combined the city-specific
estimates using a random effects approach, in total, by season and by

Results: We found a 0.98% increase [95% confidence interval (CI) ,
0.75?1.22] in total mortality, a 0.85% increase (95% CI, 0.46?1.24) in CVD,
a 1.18% increase (95% CI, 0.48?1.89) in MI, a 1.78% increase (95% CI,
0.96?2.62) in stroke, and a 1.68% increase (95% CI, 1.04?2.33) in
respiratory deaths for a 10-µg/m3 increase in 2-day averaged PM2.5. The
effects were higher in spring. For PM coarse, we found significant but
smaller increases for all causes analyzed.

Conclusions: We conclude that our analysis showed an increased risk of
mortality for all and specific causes associated with PM2.5, and the risks
are higher than what was previously observed for PM10. In addition, coarse
particles are also associated with more deaths.

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