Investigation of sources and processes influencing variation of PM2.5 and its chemical compositions during a summer period of 2020 in an urban area of Hanoi city, Vietnam

This study investigated the concentration level of PM2.5 and its chemical compositions measured in an urban area in Hanoi city, Vietnam, during July 2020. The average value of daily PM2.5 concentrations measured for the whole sampling period was slightly lower than the national standard for ambient air quality. However, there were the polluted days when PM2.5 daily concentrations exceeded the national standard in which the average concentration level was 1.82 times higher than that for the non-polluted days when PM2.5 daily concentration was below the national standard. The organic matter (OM) (including OC) and anthropogenic secondary species (NO3−, SO42 −, and NH4+) were found to be the major contributors to PM2.5 measured in the study area. Analysis of relationships among PM2.5 chemical compositions showed the strong correlations among NH4+, SO42 −, and NO3−, implying a common trend in occurrence of these species in the atmosphere. The low NO3−/SO42 − ratio suggested that stationary emissions are an important source of airborne pollutants in urban atmosphere in Hanoi. The high OC/EC ratios were influenced by either biomass burning or formation of secondary organic aerosol contributed to the high OC measured during the summer period. The characterization of aerosol associated with different air mass types showed that PM2.5 concentrations measured during July 2020 were mainly associated with three types of air mass: purely continental air masses (type I, relative...
Source: Air Quality, Atmosphere and Health - Category: Environmental Health Source Type: research