A Case-Crossover Study of Ambient Particulate Matter and Cardiovascular and Respiratory Medical Encounters Among US Military Personnel Deployed to Southwest Asia

Objective: To evaluate the impact of ambient particulate matter (PM) on acute cardiorespiratory morbidity among US military personnel in southwest Asia. Methods: We linked ambient PM data collected between December 2005 and June 2007 with personnel, medical, and meteorological data. We implemented a case-crossover analysis to estimate base-specific associations and pooled those estimates using meta-analytic methods. Results: The adjusted odds ratios for a 10-mu g/m(3) increase in ambient PM2.5 and a qualifying medical encounter were 0.92 (95% confidence interval [CI]: 0.77 to 1.11) and 1.01 (95% CI: 0.95 to 1.07) for the current (lag_0) and previous (lag_1) days. The estimates for a 10-mu g/m(3) increase in PM10 were 0.99 (95% CI: 0.97 to 1.03) at lag_0, and 1.00 (95% CI: 0.97 to 1.02) at lag_l. Conclusions: No statistically significant associations between PM and cardiorespiratory outcomes were observed in this young, relatively healthy, deployed military population.