Association between ambient sulfur dioxide pollution and asthma mortality: Evidence from a nationwide analysis in...

There is a lack of research on the effects of acute exposure to ambient sulfur dioxide (SO₂) on mortality caused by asthma, especially nationwide research in China. To explore the acute effect of exposure to ambient SO₂ on asthma mortality using nationwide dataset in China from 2015 to 2020 and further evaluate the associations in subgroups with different geographical and demographic characteristics. We used data from China's Disease Surveillance Points system with 29,553 asthma deaths in China during 2015-2020. The exposure variable was the daily mean concentrations of SO₂ from the ChinaHighSO₂ 10 km × 10 km daily grid dataset. Bilinear interpolation was used to estimate each individual's exposure to air pollutants and meteorological variables. We used a time-stratified case crossover design at the individual level to analyze the exposure response relationship between short-term exposure to SO₂ and asthma mortality. Stratified analyses were carried out by sex, age group, marital status, warm season and cold season, urbanicity and region. Significant associations between short-term exposure to ambient SO₂ and increased asthma mortality were found in this nationwide study. The excess risk (ER) for each 10 μg/m³ increase in SO₂ concentrations at lag07 was 7.78 % (95 % CI, 4.16-11.52 %). Season appeared to significantly modify the association. The associations were stronger in cold season (ER 9.78 %, 95 % CI:5.82 -13.89 %). The association remained consistent using different lag periods, adjusting for other pollutants, and in the analysis during pre-Corona Virus Disease 2019 (COVID-19) period. Our study indicates increased risk of asthma mortality with acute exposures to SO₂ in Chinese population. The current study lends support for greater awareness of the harmful effect of SO₂ in China and other countries with high SO₂ pollution.