The effect of fine and coarse particulate air pollution on mortality: a national analysis.
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 <or= 2.5 microm (PM(2.5); fine particles) and of coarse particles (particles with an aerodynamic diameter > 2.5 and < 10 microm; PM coarse). We conducted a national, multicity time-series study of the acute effect of PM(2.5) 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 1999-2005.


METHODS
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) PM(2.5) and PM coarse with daily deaths. We combined the city-specific estimates using a random effects approach, in total, by season and by region.


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-microg/m(3) increase in 2-day averaged PM(2.5). 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 PM(2.5), and the risks are higher than what was previously observed for PM(10). In addition, coarse particles are also associated with more deaths.
Zanobetti
Antonella
A
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02215, USA. azanobet@hsph.harvard.edu
Schwartz
Joel
J
D002318:Cardiovascular Diseases / Q000401:mortality; D006801:Humans; D009203:Myocardial Infarction / Q000401:mortality; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D012137:Respiratory System / Q000187:drug effects*; D012140:Respiratory Tract Diseases / Q000401:mortality; D018570:Risk Assessment; D012307:Risk Factors
D052638:Particulate Matter