Outdoor fine and coarse particles and hospital admissions for cardiovascular diseases: a large-scale case-crossover study

Abstract

Despite high levels of air pollution in the Middle East, there are relatively few studies of its impacts on population health. In this study, associations between short-term exposure to PM2.5 and PM10-2.5 and hospitalization for cardiovascular diseases (CVDs) were evaluated in a study from Isfahan, Iran. In a bidirectional case-crossover design, patients who lived in Isfahan and were admitted with a CVD diagnosis in one of 15 hospitals between March 2010 and to March 2012 were included. Time-stratified conditional logistic regression with covariates of SO2 level, weekend/weekday, temperature, dew point, and wind speed was applied to quantify the odds ratio of CVD admission per interquartile range (IQR) increase in PM. Mean (IQR) concentrations of PM2.5 and PM10-2.5 were 60.1 (39.00-63.00) and 62.4 (37.88-93.00) mu g/m(3), respectively, with 25,541 CVD admissions. There were indications of small (1-2 per IQR) increases in risk of admissions that were robust to covariate adjustment with no discernable patterns for different lags. For both PM2.5 and PM10-2.5, there were indications of larger associations for female gender and younger ages. For PM2.5, much higher ORs were observed in summer (1.21 (0.95 CI: 1.12, 1.31)) and autumn (1.14 (1.07, 1.21)) for lag period 0-1; while the PM10-2.5 effect was most prominent in autumn (1.28 (1.22, 1.33)). Small increases in risk of CVD admission were associated with exposure to fine and coarse particle levels with high seasonal variability.