Effects of Precipitation on the Air Quality Index, PM2.5 Levels and on the Dry Deposition of PCDD/Fs in the Ambient Air

The effects of 9 precipitation events in Suzhou City Anhui Province, China, on the air quality index (AQI), PM2.5, and dry deposition flux PCDD/Fs (polydibenzo-p-dioxins polydibenzofurans) were investigated. A total 7 positive contributes to reduction AQI; among them, AQI between 23 216, with an average 75, PM2.5 concentrations 5.0 169 µg m–3, 25 while total- PCDD/F-TEQ ranged from 149 1034 pg WHO2005-TEQ m–2 day–1 averaged 315 day–1. By comparing respectively, during after rainfall that before rainfall, results indicated fractions 26% 44%, those 58% 43%. In addition, effect fraction was 31%. However, other 2 elevation events, 100, 51; when concentrations, rain rain, increases 42% 49%, concentration 29%, respectively. above show that, whole, snow improved quality. This is because rainwater removes particles or dissolved gaseous pollutants atmosphere brings aerosols ground. some cases, increase source emissions atmospheric vertical convection, humidity increased elevated PCDD/Fs. this study provide useful information for both scientific communities management.