Studies on characteristics of PM2.5, PM10 and ozone pollution in Wuhan based on wavelet transform.

In order to verify the periodic law after the cooperative control of urban air pollutants emission, wavelet transform was used to analyse daily PM2.5, PM10 and ozone concentration data of 2421 days (d) from 2013 to 2020 in Wuhan. The results are as follows: Inhalable particulate matter pollution had been reduced year by year. From 2014 to 2019, the annual average concentration of PM2.5 had reduced from 80.5µg/m3 to 45.3µg/m3, and that of PM10 had reduced from 113.6µg/m3 to 72.6µg/m3, which means the excessive rate of PM2.5 was reduced from 44% to 11%, and that of PM10 was reduced from 22% to 2%. The ozone pollution had kept unabated, with the annual average concentration of ozone fluctuating between 90µg/m3 to 100µg/m3. The concentration of all three kinds of pollutants displayed clear periodicity. PM2.5, PM10 and ozone concentration displayed with a same primary period of 300d. On the contrary, the secondary period of the three pollutants were 140d, 125d, and 143d respectively. PM2.5 and PM10 had similar periods and phases, which indicates that pollution behaviours of both particulate matters are consistent. Furthermore, the concentration of the three pollutants had a positive correlation was revealed in short period (0~64d), whereas a negative correlation in long period of about 300d. © 2023 Chinese Society for Environmental Sciences. All rights reserved.