Association between short-term exposure to sulfur dioxide and carbon monoxide and ischemic heart disease and non-accidental death in Changsha city, China

Background To investigate the effects of short-term exposure to sulfur dioxide (SO2) and carbon monoxide (CO) in the central and southern China areas on ischemic heart disease (IHD) and nonaccidental deaths. Method We investigated the associations between short-term exposure to SO2 and CO in a city in south-central China and IHD and non-accidental death using a time-series design and generalized additive models with up to a 5-day lag adjusting for day of the week, temperature, air pressure, wind speed, and relative humidity. The relative risks of IHD and non-accidental death per 10-unit increase in SO2 and CO were derived from zero to five days in single-pollutant models. Results Between 2016 and 2018, a total of 10,507 IHD and 44,070 non-accidental deaths were identified. The largest significant relative risk for IHD death was lag 02 for both SO2 (1.080; 95% confidence interval: 1.075-1.084) and CO (5.297; 95% confidence interval: 5.177-5.418) in single-pollutants models. A significant association was shown at all lag multiple-day moving averages. Two-pollutant models identified an association between SO2 and mortality when adjusting for CO. In stratified analyses, SO2 exhibited a stronger association with death during the cold season, while CO exhibited a stronger association with mortality from IHD during the warm season. The risk of death was more robust in the elderly for both pollutants, but was greater in men for CO and in women for SO2. Conclusions Overall, we found an association between short-term exposure to low-level SO2 and CO and the risk of IHD and non-accidental death.