Impact of COVID-19 Prevention and Control Measures on Air Pollutants in Nanjing

To study the effects of the prevention and control measures of COVID-19 in early 2020 on the concentrations of air pollutants, industrial and traffic emissions in Nanjing, the air environment during COVID-19 in 2020 and the same period in 2019 were simulated using the regional chemical online coupling model WRF-Chem, and the results were verified using air quality observation data. The results show that (1) the WRF-Chem model can better simulate the trends of air pollutants in Nanjing; (2) influenced by the epidemic prevention and control measures, the concentrations of PM 2.5 , PM 10 , and NO 2 in Nanjing decreased by 15%, 17.1%, and 20.3%, respectively, while the O 3 concentration increased by 45.1% compared with the same period in 2019. (3) The impact of the epidemic prevention and control measures on industrial and traffic pollutant emissions in Nanjing was quantified by using the "zero-out" method, and industrial pollutant PM 2.5 , PM 10 , and NO 2 concentrations decreased by 30.7%, 30.8%, and 14.0%, while traffic pollutant PM 2.5 , PM 10 , and NO 2 concentrations decreased by 15.6%, 15.7%, and 26.2%. The results provide an important basis for future air pollution management in Nanjing.