Source identification using principal component analysis and health risk assessment of heavy metals contamination in PM_2.5 near an industrial area in Thailand

Industrialization has led to a surge in air pollution-related problems, as particulate matter (PM) containing heavy metals poses significant health risks. Understanding airborne particle chemistry, particularly the presence of heavy metals, is vital for effective air quality management and health interventions. This study analysed heavy metal levels in PM_2.5 across various sites near an industrial zone in Thailand, including areas near main roads, the industrial zone, as well as indoor and outdoor areas of childcare centres. The concentrations of ambient PM_2.5 were found to exceed national standards and acceptable limits during the cool dry season, particularly in the industrial zone (46.4 µg/m³), followed by areas near main roads (41.0 µg/m³) and childcare centres (31.6 µg/m³). The impact of the indoor–outdoor relationship on PM_2.5 concentration within childcare centres varied. During the cool dry season, Aluminium had the highest concentration, while lead (Pb) across all sites raised environmental concerns. Remarkably, indoor childcare centres showed higher Pb levels than industrial zones and areas near the main road. Principal Component Analysis revealed the distinct factors linked to specific metals, implying contributions from industrial and transportation sources. Lead isotopic analysis indicated potential associations between lead sources and industries like smelting and refining. During the cool dry season, non-carcinogenic risks were concerning (HI > 1), especially near roads and industrial areas. Vulnerabilities were also observed in students and teachers within indoor childcare centres. This study underscores the importance of monitoring and reducing heavy metal pollution in PM_2.5, especially in childcare centres near industrial zones, to preserve public health and regional air quality.