Association of short-term exposure to sulfur dioxide and hospitalization for ischemic and hemorrhagic stroke in Guangzhou, China

Background In developing countries, ambient sulfur dioxide (SO2) is a serious air pollutant concern, but there is no enough and consistent epidemiological evidence about its health effects on stroke hospitalization. Methods We collected the daily air pollution data, meteorological data and number of daily hospital admissions for ischemic and hemorrhagic stroke, in Guangzhou from January 1st 2009 to December 31st 2014. Then we applied generalized additive model with a quasi-Poisson link to assess the relationship between short-term SO2 exposure and the total number of hospital admissions for ischemic and hemorrhagic stroke. In addition, we evaluated the effect of ambient SO2 by age (< 65 years and >= 65 years). Results During the study period, a 24-h mean concentration of ambient SO2 of 27.82 mu g/m(3), a total of 58,473 ischemic stroke and 9167 hemorrhagic stroke hospital admissions hospital were recorded. Ambient SO2 was found to increase the risk for both ischemic and hemorrhagic stroke hospital admission in single pollutant model. The maximum value of percentage changes for ischemic and hemorrhagic stroke occurred in lag 0 day and lag 1 day, per 10 mu g/m(3) increase in SO2 concentrations was corresponded to a 1.27% (95% confidence interval (CI), 0.42-2.12%) and 1.55% (95%CI, 0.02-3.11%) increased risk, respectively. The association between SO2 and ischemic stroke hospitalization was robust to two pollutant model, but for hemorrhagic stroke it's partially weakened after adjusting for co-pollutants. The effect of ambient SO2 on ischemic stroke appeared to be greater for people < 65 years old, but null effect on hemorrhagic stroke was identified for both age groups. Conclusions We found short-term exposure to ambient SO2 may significantly increase the risks of hospitalization for ischemic stroke. The findings may contribute to a better understanding of the health effects of low-levels of SO2.