The lag structure between particulate air pollution and respiratory and cardiovascular deaths in 10 US cities

To assess differences in the lag structure pattern between Particulate matt er < 10 mum/100 mum in diameter (PM10) and cause-spec flc mortality, we per formed a time-series analysis in 10 US cities using generalized additive Po isson 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 cumul ative 7-day effect by means of an unconstrained distributed lag model. A 10 -mug/m(3) 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 (2.7%, 95% CI: 0.1, 3.3), and all car diovascular diseases (1.0%, 95% CI. 0.6, 1.4). A 10-mug/m(3) increase in th e 2-day mean of PM10 was associated with a 0.7% (95% CI: 0.3, 1.1) increase in deaths from myocardial infarction. Men the distributed lag was assessed , two different patterns could be observed: respiratory deaths were more af fected 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 pollutio n promotes adverse health effects.