Purpose: The evidence for a causal relationship between high-level ozone (O₃) exposure and acute exacerbation of asthma among adults is limited, and the conclusions are less definitive.
Patients and methods: Here we collected the daily data on asthma cases, O₃ exposure, and meteorological factors from 2010 to 2016 in Shijiazhuang, China. We investigated the risk of asthma exacerbation associated with high-level ozone exposure using a polynomial distributed lag model (PDLM). Using a generalized additive model (GAM), we estimated the interactive effects between O₃ and other pollutants as well as meteorological factors on asthma exacerbation.
Results: A total of 7270 patients with asthma were enrolled from 22 governmental hospitals in 13 counties. Each 10 μg/m³ increase in O₃ concentration on the exacerbation of asthma was associated with a 1.92% (95% CI = 0.80– 3.03%) higher risk of asthma exacerbation on day lag 7. The cumulative risk of O₃ on asthma exacerbation increased by 18.9% (95% CI = 12.8– 25.4%) on the 14th day. High consecutive levels of O₃ increase the risk of asthma exacerbation, and the interactive effect of O₃ and sulfur dioxide (SO₂) appears before the exacerbation onset.
Conclusion: These findings suggested that O₃ should be an important risk factor for asthma exacerbation, and health benefits in reducing asthma exacerbation risk would be gained with continued efforts to improve the air quality in China.
Keywords: ozone, asthma exacerbation, PDLM, GAM, interaction