Abstract
The impact of temporary control measures on regional air quality during large-scale events is the focus of current research. Most of them focus on the discussion of environmental particulate matter concentration, while the changes in O3 concentration during such periods have not been explored. To reveal the variation characteristics of environmental O3 concentration during large-scale events, the ozone pollution control during the 2019 National Games in Zhengzhou, China was considered as an example and the six pollution parameters of state-controlled stations, meteorological parameters, and online volatile organic compound (VOC) component data was used. The evolution law of O3 pollution in Zhengzhou before and after the implementation of control measures was discussed, and the changes in NOx and the components of VOCs in different control stages were compared. The positive matrix factorization model was used to analyze the contribution of different types of pollution sources to the O3 mass concentration in Zhengzhou during the observation period. Results show that during the National Games, the concentration of O3 decreased by 45.2% and 29.3% compared with that before control and during Stage-I of control, respectively. The concentration of alkanes, olefins, and alkynes decreased significantly during the National Games, whereas the concentration of aromatic hydrocarbons increased by 6.5%. The pollution sources with the highest contribution of VOCs in Zhengzhou were as follows: motor vehicle tail gas source (the average contribution was 32.8%), natural gas/oil source (26.3%), solvent use source (20.4%), industrial process source (13.9%), and natural plant source (6.7%). The research conclusion revealed the evolution characteristics of O3 concentration and the causes of pollution during large-scale activities.
Key Words: O3 pollution, VOCs, Control measures, the National Games, PMF source apportionment