Exposure risk assessments and environmental impacts of surface ozone in Chongqing during 2015~2022
To comprehensively evaluate the potential health and environmental impacts of surface ozone(O3),along with its role in the secondary aerosol formation,long-term variations of O3 in Chongqing during 2015~2022 were examined in this study.Risk assessments of long-term O3 exposure on health,economy and vegetation were comprehensively characterized by multiple indices,with a specific focus on the exposure risk assessments of short-term persistent O3 pollution,as well as its potential impacts on the nocturnal nitrate formation.Results indicated that an overall upward trend was exhibited in the surface O3 in Chongqing in recent years,with the nocturnal O3 levels increased gradually.Especially,the surface O3 exceedance in spring should be paid more attention.Generally,all the long-term O3 exposure risk indices were ascended during 2015~2019 and subsequently decreased with fluctuations.The corresponding exposure risks of short-term persistent O3 pollution were increased significantly in comparison to both pre-and post-pollution periods.The production rate of NO3(PNO3)might be intensified by the elevated nocturnal O3,thereby promoting the heterogeneous hydrolysis of N2O5 and the nocturnal nitrate formation.This phenomenon was pronounced in pollution episodes,specifically under high relative humidity conditions.This signifies the importance to further investigate the nocturnal O3 related exposure risks and impacts on the formation of secondary inorganic aerosols.