To assess differences in the lag structure pattern between particulate matter <10 μm/100 μm in diameter (PM10) and cause-specific mortality, we performed a time-series analysis in 10 US cities using generalized additive Poisson regressions in each city; nonparametric smooth functions were used to control for long time trend, weather, and day of the week. The PM10 effect was estimated based on its daily mean, 2-day moving average, and the cumulative 7-day effect by means of an unconstrained distributed lag model. A 10-μg/m3 increase in the 7-day mean of PM10 was associated with increases in deaths due to pneumonia (2.7%, 95% confidence interval [CI]: 1.5, 3.9), chronic obstructive pulmonary disease (1.7%, 95% CI: 0.1, 3.3), and all cardiovascular diseases (1.0%, 95% CI: 0.6, 1.4). A 10-μg/m3 increase in the 2-day mean of PM10 was associated with a 0.7% (95% CI: 0.3, 1.1) increase in deaths from myocardial infarction. When the distributed lag was assessed, two different patterns could be observed: respiratory deaths were more affected by air pollution levels on the previous days, whereas cardiovascular deaths were more affected by same-day pollution. These results contribute to the overall efforts so far in understanding how exposure to air pollution promotes adverse health effects.
From the Environmental Epidemiology Program, Department of Environmental Health, Harvard School of Public Health (Dr Braga, Dr Zanobetti, Dr Schwartz); and the Environmental Pediatrics Program, Department of Pediatrics, University of Santo Amaro School of Medicine, and Laboratory of Experimental Air Pollution, Department of Pathology, University of São Paulo School of Medicine, São Paulo, Brazil (Dr Braga).
This work was supported in part by National Institute of Environmental Health Sciences grant ES 0002 and Environmental Protection Agency Research Center Award R 827353. Alfésio Braga has personal grants from São Paulo State Research Support Foundation (FAPESP) (98/130214) and the University of Santo Amaro (UNISA).
Address correspondence to: Joel Schwartz, PhD, Environmental Epidemiology Program, Department of Environmental Health, Harvard School of Public Health
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