Effect of outdoor particulate air pollution on FEV1 in healthy adults: a systematic review and meta-analysis

The effect of acute and long-term exposures to outdoor particulate air pollution on lung function in healthy adults is not well established. The objective of this study was to conduct a systematic literature review and meta-analysis of studies that assessed the relationship of outdoor particulate air pollution and lung function in healthy adults. Studies that contained data on outdoor air particulate matter levels (PM10 or PM2.5) and forced expiratory volume in 1 s (FEV1) in healthy adults were eligible for inclusion. Effect estimates, in relation to long-term and acute exposures, were quantified separately using random effects models. A total of 27 effect estimates from 23 studies were included in this review. Acute exposures were typically assessed with PM2.5, while long-term exposures were predominantly represented by PM10. A 10 mu g/m3 increase in short-term PM2.5 exposure (days) was associated with a -7.02 mL (95% CI -11.75 to -2.29) change in FEV1. A 10 mu g/m(3) difference in long-term PM10 exposure was associated with a -8.72 mL (95% CI -15.39 to -2.07) annual change in FEV1 and an absolute difference in FEV1 of -71.36 mL (95% CI -134.47 to -8.24). This study provides evidence that acute and long-term exposure to outdoor particulate air pollution are associated with decreased FEV1 in healthy adults. Residual confounding from other risk factors, such as smoking, may explain some of the effect for long-term exposures. More studies are required to determine the relationship of long-term exposure to PM2.5 and short-term exposure to PM10, which may have different biologic mechanisms.