Assessment of the status of PM2.5 and ground-level O3 pollution variations and meteorological factor effects: A case study in Long An Province, Vietnam

Abstract

Abstract Long An Province has a favorable geographical position in socio-economic development exchanges and is a fundamental bridge between the area of Ho Chi Minh City (HCMC) and the Southeast localities with the Southwestern provinces. Along with the master plan for socio-economic development with a vision for 2030, the province’s air quality issues, especially PM2.5 and surface O3 pollution, will be complex and pose many challenges to effective air pollution management and control. This study aims to investigate the effects of major meteorological characteristics (temperature–T, relative humidity–RH, surface pressure–P, and wind speed–WS) on temporal changes in the correlation between PM2.5 and surface O3 concentrations in Long An province in the 2018-2020 period (computed by a system of coupled WRF/CMAQ models) through trend evaluation using by Mann-Kendall (MK) Test and Theil-Sen Slope, and Pearson correlation analysis. The study results reported that in terms of temporal variations, both value levels of PM2.5 and O3 in the dry season tended to surpass that in the rainy season. Moreover, PM2.5 levels tended to exceed the 24-hour mean threshold (between 1.001 and 3.14 times) and the annual mean threshold (from 1.81 to 2.03 times) of the Vietnamese National Ambient Air Quality Standard. Based on the Pearson correlation analysis, significant influences of meteorological conditions on the pollution status of PM2.5 and surface O3 were also demonstrated, such as the different positive and negative correlations of each meteorological factor on concentration. These outstanding results serve as an essential reference for developing air quality targets and proposing future air pollutant control measures in Long An Province.