Exploring the Impact of COVID-19 on the Air Quality in China (preprint)

ABSTRACT

At the end of 2019, the COVID-19 emerged in Wuhan, China. It has since put global public health institutions on high alert. People in China reduced their traveling, and production has stopped nationwide during the height of the epidemic. This study explores the effects of these COVID-19-derived changes on air quality in China. Air quality data of 367 cities around China were analyzed. The daily air quality index and air pollutant concentrations (CO, O3, NO2, SO2, PM10, and PM2.5) were collected and compared the epidemic period (23.1.2020-23.3.2020) with the preceding two months (22.11.2019-22.1.2020) and the parallel period the year before (23.1.2019-23.3.2019).To compare, we calculated the daily average number of cities with pollution, and the trend in air quality index change. The air quality in the 50 cities with the highest number of confirmed COVID-19 cases and Wuhan was also analyzed. During the period between 23.1.2020 and 23.3.2020, the number of cities with excellent air quality was significantly higher than that in the other two periods. The concentrations of PM2.5, PM10, NO2, SO2, CO, and O3 decreased significantly during this period. The most significant decreases were in PM10 and NO2. The number of cities with good air quality in the later period was significantly higher than a year before. The air quality has improved significantly during the COVID-19 outbreak. The reason for this change might be changes in human activities such as reduced transportation and production stoppage.