Short-term effects of fine particulate air pollution on hospital admissions for cardiovascular diseases: a case-crossover study in a tropical city.

This study was undertaken to determine whether there was an association between fine particles (PM2.5) levels and hospital admissions for cardiovascular diseases (CVD) in Kaohsiung, Taiwan. Hospital admissions for CVD (including ischemic heart disease [IHD], stroke, congestive heart failure [CHF], and arrhythmias) and ambient air pollution data for Kaohsiung were obtained for the period from 2006-2010. The relative risk of hospital admissions for CVD was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single-pollutant model (without adjustment for other pollutants), elevated number of admissions for CVD were significantly associated with higher PM2.5 levels only on cool days (<25°C), with an interquartile range rise associated with a 47% (95% CI = 39-56%), 48% (95% CI = 40-56%), 47% (95% CI = 34-61%), and 51% (95% CI = 34-70%) increase in IHD, stroke, CHF, and arrhythmias admissions, respectively. No significant associations between PM2.5 and hospital admissions for CVD were observed on warm days. In the two-pollutant models, PM2.5 levels remained significant even controlling for sulfur dioxide, nitrogen dioxide, carbon monoxide, or ozone on cool days. This study provides evidence that higher levels of PM2.5 enhance the risk of hospital admissions for CVD in Kaohsiung, Taiwan.