A comprehensive study on the spatial and temporal variation of BTEX and asbestos in the northwest of Iran: Human risk assessment.

Substances like asbestos and other air pollutants, such as BTEX (benzene, toluene, ethylbenzene, and xylene), are hazardous compounds due to their adverse effects on human health. This study aims to investigate the levels, seasonal variations, spatial distribution, potential sources, and associated health risks associated with BTEX compounds and asbestos fibers in the ambient air of Tabriz. Air samples were taken at 16 different locations during the 2020-2021 period. Glass containers with charcoal were used for sample collection, and the BTEX content was determined using the GC-FID method. Phase-contrast microscopy (PCM) analysis was conducted with a low-volume peripheral pump for asbestos fiber sampling. The results showed that the average concentration of ∑BTEX was 37.94 and 27.98 μg/m in autumn and spring, respectively. The same parameter was 2.26 and 1.68 f/L for asbestos in the autumn and winter, respectively. The contribution of BTEX to ozone formation potential (OFP) in the research area showed that xylene and toluene were the major contributors to ozone production in different seasons. The risk of exposure to benzene compounds was 24 × 10 in children and 55.9 × 10 in adults, while the risk of exposure to ethylbenzene was 3.78 × 10 in children and 3.25 × 10 in adults. The estimated lifetime cancer risk was found to be the highest for benzene, followed by ethylbenzene. The estimated cancer risk for benzene and ethylbenzene exceeded the threshold values set by EPA, which signals a significant carcinogenic risk due to exposure to these substances in the ambient air of Tabriz. According to the EPA guidelines, the low carcinogenicity risk levels are between 10 and 10. According to the findings for the exposure to asbestos fibers, the maximum values of excess cancer risk (ECR) and estimated lifetime cancer risk (ELCR) were observed in the 16-30 age range across all locations, suggesting increased exposure to asbestos fibers compared to other age groups.