Abstract

Since 2013, the Ministry of Natural Resources and Environment published the revision of the “National Technical Regulation on Ambient Air Quality” (QCVN 05:2013/BTNMT), in which the fine particulate matter (PM2.5) was added to the QCVN. However, the status and the temporal variation of PM2.5 in Ho Chi Minh City (HCMC) have not been reported so far, especially based on the continuous and high time resolution measurements. The aim of this study was to analyze the status and the temporal variation of PM2.5 collected at the center of HCMC. Based on the composited PM2.5 data from the air monitoring station located at the University of Science, the average PM2.5 concentration was 28.0 ± 18.1 µg/m³ during 2013– 2017. The annual PM2.5 concentration in HCMC exceeded the acceptable limits of QCVN and WHO, highlighting a high human health risk. The PM2.5 concentrations showed the pronounced diurnal variation with the highest observed after the morning rush hour and the lowest during the midnight. In addition, a remarkable seasonal variation was observed with the highest and lowest PM2.5 occurring in dry and rainy seasons, respectively. This result highlighted the vital role of the rainfall events in reducing the PM2.5 level. Finally, from the analysis of the backward trajectories ending at the air monitoring station, we found that the air mass from the North and Northeast originating from China then passing through the areas (i.e. Binh Duong and Dong Nai provinces) with heavy industrial activities possessed a high PM2.5 level.