Abstract

This study aims to assess the health risks of potentially toxic elements (PTEs) in PM<inf>2.5</inf> in Upper Southeast Asia during the dry season, particularly during the smoke haze (SH) period. An analysis of six PTEs (As, Cd, Cr, Co, Ni, and Pb) revealed that lower concentration ratios of Cd (0.959 ± 0.299), Pb (0.955 ± 0.227), As (0.836 ± 0.216), and Ni (0.401 ± 0.989) were observed at nighttime when compared with daytime, while Co (1.924 ± 2.267) and Cr (1.416 ± 2.583) exhibited the opposite trend. Regarding the health risk assessment for non-carcinogenic effects, children experienced a low hazard risk (HI: 0.1-1). Ingestion has been identified as the main exposure pathway for both children and adults. For carcinogenic effects, the lifetime cancer risk (LCR) indicates high carcinogenic risk for residents (LCR > 10^-3), with inhalation being the primary exposure pathway for both age groups. When comparing exposure times, nighttime may pose greater health risks than daytime for both non-carcinogenic and carcinogenic effects. Overall, our findings provide a better understanding of variations in PTEs in PM<inf>2.5</inf> during different exposure times and the relevant negative impacts. These insights are particularly useful for residents in Upper Southeast Asia, especially those living in open-air buildings and engaging in nighttime activities, as they highlight the need for action to minimize the chronic impacts of air pollution and align with the United Nations' Sustainable Development Goal 3.9. Moreover, our findings emphasize the need for increased attention to air pollution to significantly reduce risks to ecosystems.