Health risk assessments and source apportionment of PM2.5-bound heavy metals in the initial eastern economic corridor (EEC): A case study of Rayong Province, Thailand

Abstract

This study aimed to determine the metals in ambient PM_2.5 in the expanding industrial metropolitan area of Rayong Province for health risk assessment and source apportionment from May 2022 to April 2023, covering wet and dry seasons. The mean annual PM_2.5 concentration was 15.2 ± 12.0 μg m⁻³, whereas that of wet and dry seasons were 8.4 ± 5.4 μg m⁻³ and 21.8 ± 12.9 μg m⁻³, respectively. The annual PM_2.5 level exceeded the limit set by the World Health Organization (WHO) (5 μg m⁻³) and the standard of Thailand (15 μg m⁻³). A substantial decrease in the Cd, Pb, Zn, Cu, Fe, Mn, and K concentrations was observed during the wet season compared with that of the dry season. The levels of annual Cr in PM_2.5 were 40 times higher than the WHO limit. Cd, Pb, and Zn are tracers of anthropogenic activities. Using the enrichment factor (EF) and I_geo, the contamination of As, Cd, Pb, and Zn suggested that the initial Eastern Economic Corridor (EEC) in Rayong Province was highly polluted. The results of the non-carcinogenic risk indicated that human health was notably affected by toxic metals in PM_2.5, and the Cr-related carcinogenic risk in PM_2.5 exposure suggested a safe or reasonable risk level (10⁻⁶ to 10⁻⁴). Exposure to toxic metals in PM_2.5 increases the risk of developing cancer in adults, potentially owing to the accumulation of these metals within the tissues in the body. Positive matrix factorisation (PMF) suggested that the source apportionment of PM_2.5-bound heavy metals was motor vehicles (34.7%), industrial activities (26.3%), biomass burning (22.7%), and road dust (18.5%).