Short-term exposure to sulfur dioxide and the risk of childhood hand, foot, and mouth disease during different seasons in Hefei, China

Background: Sulfur dioxide (SO₂) is an important component of air pollution, adversely impacting human health worldwide. This study aimed to examine the association between short-term exposure to SO₂ and childhood hand, foot, and mouth disease (HFMD) in Hefei, China.

Methods: A Poisson generalized additive model (GAM) combining the time-series regression analyses was used to fit the SO₂-HFMD association. The effect of SO₂ was estimated using the single-day lag models (lag0, lag1, lag2) and the moving average lag models (lag01, lag02) We also conducted stratified analyses by season, ages (0-4 years old, 5-14 years old), gender (male, female), childcare patterns (scattered children, kindergarten children) and residence areas (urban, rural). Two-pollutant models were adopted to test the robustness of the results.

Results: There was a statistically significant association between SO₂ and the risk of childhood HFMD. For total cases, the relative risk (RR) at lag0 was 1.038 (95% confidence interval (CI): 1.018-1.057) in whole-period and 1.088 (95% CI: 1.059-1.118) in cold season. During cold season, we observed significant associations between SO₂ and HFMD among all subgroups except for children aged 5-14 years old and the adverse effects occurred on lag0, lag1, lag01, lag02. However, in hot season, SO₂ were significant only for females (lag01 with RR = 1.054; 95%CI = 1.007-1.101) and scattered children (lag01 with RR = 1.054; 95%CI = 1.007-1.101). In general, females and scattered children appeared to be more vulnerable to SO₂.

Conclusions: This study suggests a significant association between SO₂ and HFMD. especially during cold season. Compared with males and kindergarten children, females and scattered children are at higher risk of developing HFMD.