The Modulation of Meteorological Parameters on Surface PM2.5 and O3 Concentrations in Guangzhou, China

PM2.5 and ozone (O3) are two major pollutants that are worsening air quality in China. Using Guangzhou as a case study, we analyzed the meteorological data and air quality data for 2014–2016 obtained by 4 weather stations and 10 environmental monitoring stations, respectively, and assessed the influence of significant meteorological parameters on the hourly PM2.5 concentration and the daily maximum 8-hour-averaged (MDA8) O3 concentration. Calculating each factor’s critical values for these concentrations, we found that the hourly PM2.5 concentration tended to increase when the relative humidity was > 50%, the hourly rainfall intensity was ≤ 0.6 mm hour–1, or the wind speed was ≤ 1.8 m s–1 but otherwise decreased, whereas the MDA8 O3 concentration tended to increase when the sunshine duration was > 4 hours, the maximum temperature was > 29°C, or the average daily wind speed was ≤ 1.8 m s–1 but otherwise decreased. The wind direction was also a crucial factor, as Guangzhou typically experienced severe air pollution when westerlies prevailed. Applying the critical values of these various meteorological parameters as indicators of air quality, we discovered that the least favorable weather conditions during the study period occurred in 2014. These results further our understanding of the relationship between weather conditions and pollutant concentrations. Following the novel approach proposed in this study, meteorological parameters can be utilized to forecast the air quality or compare the effects of weather on pollution between different years.