Ambient Ozone Pollution and Daily Mortality in Hohhot, China: A Time-Series Study

Evidence on the effects of ozone on chronic lower respiratory disease (CLRD), acute respiratory infections (ARI) is still not conclusive. This study aimed to investigate the association between them in Hohhot China. Daily death counts, concentrations of PM2.5, PM10, SO2, NO2, and O3, and meteorological data were collected for Hohhot city from January 1, 2018, to December 31, 2019. We performed a time series analysis using generalized additive model (GAM). In single pollutant model, the estimated excess relative risks (EERs) for respiratory and CLRD mortality were 2.815% (95% CI: 0.075–5.630) at lag 04 and 4.409% (95% CI: 1.577–7.320) at lag 01, respectively, for each 10 µg/m3 increase in O3. No significant association was found for ARI and the other respiratory diseases mortality. Subgroup analysis showed that the respiratory diseases for men were more susceptible to O3 than women, while men had a lower association with CLRD than women. Concentrations of O3 were significantly associated with respiratory disease and CLRD for older adults. The significant positive association between O3 and respiratory mortality and CLRD mortality remained largely unchanged in the two-pollutant model and the multi-pollutant model. In conclusion, short-term exposure to O3 is significantly associated respiratory diseases and CLRD mortality, and this association is dominated by gender and age.