Objective:The purpose of this study was to examine the association between ozone(03)exposures and asthma attacks in children,and to provide scientific evidence for the health effects of ozone in the future.Methods:The data of asthma attacks in children from the First Affiliated Hospital of Xiamen University,air pollution data and meteorological data in Xiamen during 2016-2019 were collected.A case-crossover design and logistic regression models were conducted to evaluate the association between outdoor air pollution(O3,NO2,SO2,CO,PM2.5,PM10)and asthma attacks.The effects of air pollutants were investigated at lag 0 to lag 6 in both single and multi-pollutant models.Furthermore,we estimate the effect of various levels of ozone exposure on asthma attack.Each lag model is divided into 3 groups by O3-8h(>=100μg/m3,80-99μg/m3,<80μg/m3).Results:1.A total of 3714 cases of asthma attacks in children from the First Affiliated Hospital of Xiamen University during 2016 to 2019 were included in this study.Among them,male children accounted for 69.15%,and children younger than 6 years old accounted for 60.07%.2.The data of air pollutants and meteorological shows that the average daily maximum 8-hour average concentration of ozone in Xiamen during 2016-2019 was 81.21μg/m3,and the number of days exceeding the first-level standard was 361 days(24.7%).The average concentrations of NO2,PM2.5,and PM10 were 29.02μg/m3,12.057μg/m3 and 44.85μg/m3,respectively,and the proportion of days exceeding the first-level standard was 0.34%,7.94%and 33.26%,respectively.The daily average concentration of CO and SO2 did not exceed the first-level standard.3.In the single-pollutant model,it is found that the effect of ozone in the 3 days before the asthma attack is the largest,that is,the best lag period is lag 3.And every 10μm3 increase of O3-8h,the risk of asthma attack increased by 0.35%(95%CI:0.07%~0.63%,P<0.05).Every 10μg/m3 increase of PM2.5,PM10,NO2,SO2,and CO in lag 2 were positively associated with asthma attack in children,with odds ratios of 1.0078(95%CI:1.0033-1.0125)and 1.0075(95%CI:1.0045-1.0105),1.6842(95%CI:1.1177-2.5380),1.0297(95%CI:1.0149-1.0448),respectively.Every 10mg/m3 increase of CO,the odds ratio is 1.0144(95%CI:1.0095-1.0192).4.In the dual-pollutant mode,the effects of O3,PM2.5,PM10,SO2 and NO2 on asthma attacks are similar to the results of the single-pollutant model.5.In the multi-pollutant model,NO2,PM2.5 and PM10 are associated with asthma attacks,with OR of 1.0136(NO2,lag2,95%CI:1.0067-1.0206),0.9839(PM2.5,lag3,95%CI:0.9722-0.9957),1.0105(PM10,lag2,1.0038-1.0173)and 1.0121(PM10,lag3,1.0033-1.0210),respectively.The association between ozone and asthma attacks in lag 3 is weakened.6.The single-pollutant models in different lag periods show that ozone is positively correlated with asthma attacks when O3-8h is greater than or equal to 80μg/m3 and the effect is significantly enhanced when O3-8h is greater than or equal to 100μg/m3,respectively,after a lag of 2 days(OR:1.0427,95%CI:1.0345-1.0509)and 6-day lag(OR:1.1285,95%CI:1.1099-1.1474)have the strongest effects.O3-8h<80μg/m3 is negatively correlated with asthma attacks.7.The multi-pollutant model with different ozone levels in different lag periods shows that the health effect of ozone on asthma attacks is the same as that of the single-pollutant model.When O3-8h is greater than or equal to 80μg/m3,asthma attack is positively correlated with ozone.When O3-8h<80μg/m3,asthma attack is negatively correlated with ozone.NO2 was found to be positively correlated with asthma attacks when O3-8h≥100μg/m3 and O3-8h<80μg/m3.CO is positively correlated when O3-8h≥100μg/m3,and negatively correlated when O3-8h<80μg/m3.PM10 is positively correlated with asthma attacks at relatively low levels of O3-8h,and negatively correlated with asthma attacks at O3-8h<80μg/m3.PM2.5 is positively correlated when O3-8h<80μg/m3.The above correlations are all statistically significant.Conclusion:Short-term exposure to outdoor air pollution(O3、PM2.5、PM10、NO2)increases the risk of asthma attack.A relatively low level of ozone(below the national air quality level 1 standard)will increase the risk of asthma attacks in children.The higher theozone,the stronger the harm.When O3-8h is lower than 80μg/m3,ozone has not been found to be harmful to asthma attacks. |