Comparison of the association between different ozone indicators and daily respiratory hospitalization in Guangzhou, China

BACKGROUND: Epidemiological studies have widely proven the impact of ozone (O(3)) on respiratory mortality, while only a few studies compared the association between different O(3) indicators and health. METHODS: This study explores the relationship between daily respiratory hospitalization and multiple ozone indicators in Guangzhou, China, from 2014 to 2018. It uses a time-stratified case–crossover design. Sensitivities of different age and gender groups were analyzed for the whole year, the warm and the cold periods. We compared the results from the single-day lag model and the moving average lag model. RESULTS: The results showed that the maximum daily 8 h average ozone concentration (MDA8 O(3)) had a significant effect on the daily respiratory hospitalization. This effect was stronger than for the maximum daily 1 h average ozone concentration (MDA1 O(3)). The results further showed that O(3) was positively associated with daily respiratory hospitalization in the warm season, while there was a significantly negative association in the cold season. Specifically, in the warm season, O(3) has the most significant effect at lag 4 day, with the odds ratio (OR) equal to 1.0096 [95% confidence intervals (CI): 1.0032, 1.0161]. Moreover, at the lag 5 day, the effect of O(3) on the 15–60 age group was less than that on people older than 60 years, with the OR value of 1.0135 (95% CI: 1.0041, 1.0231) for the 60+ age group; women were more sensitive than men to O(3) exposure, with an OR value equal to 1.0094 (95% CI: 0.9992, 1.0196) for the female group. CONCLUSION: These results show that different O(3) indicators measure different impacts on respiratory hospitalization admission. Their comparative analysis provided a more comprehensive insight into exploring associations between O(3) exposure and respiratory health.