Ambient Coarse Particulate Matter and Human Health: A Systematic Review and Meta-Analysis

Airborne particles have been linked to increased mortality and morbidity. As most research has focused on fine particles (PM(2.5)), the health implications of coarse particles (PM(10-2.5)) are not well understood. We conducted a systematic review and meta-analysis of associations for short- and long-term PM(10-2.5) concentrations with mortality and hospital admissions. Using 23 mortality and 10 hospital admissions studies, we documented suggestive evidence of increased morbidity and mortality in relation to higher short-term PM(10-2.5) concentrations, with stronger relationships for respiratory than cardiovascular endpoints. Reported associations were highly heterogeneous, however, especially by geographic region and average PM(10-2.5) concentrations. Adjustment for PM(2.5) and publication bias resulted in weaker and less precise effect estimates, although positive associations remained for short-term PM(10-2.5) concentrations. Inconsistent relationships between effect estimates for PM(10-2.5) and correlations between PM(10-2.5) and PM(2.5) concentrations, however, indicate that PM(10-2.5) associations cannot be solely explained by co-exposure to PM(2.5). While suggestive evidence was found of increased mortality with long-term PM(10-2.5) concentrations, these associations were not robust to control for PM(2.5). Additional research is required to better understand sources of heterogeneity of associations between PM(10-2.5) and adverse health outcomes.