Spatio-seasonal variation, distribution, levels, and risk assessment of airborne asbestos concentration in the most industrial city of Iran: effect of meteorological factors.

Like other dangerous pollutants in the air, asbestos has negative and adverse effects on human and animal health. The present study is designed to determine the concentration of asbestos in the air of the most industrial city of Iran (Karaj) in 2018-2019. For this purpose, 4 samples were taken from different areas of the air of Karaj during a year with an SKC pump and flow of 6 L/min for 8 h and in 45 days, and a total of 68 samples of asbestos fibers were collected. Then, the samples were analyzed by phase-contrast microscope (PCM) and scanning electron microscopy (SEM). Eventually, the health effects of asbestos fibers were evaluated by the IRIS EPA method. The average concentration of asbestos fibers was 1.84 f/L PCM and 18.16 f/L SEM. Also, the results of statistical correlation analysis indicated that asbestos fibers are positively correlated with wind speed but negatively correlated with the other three parameters (temperature, relative humidity, and pressure). On the other hand, the average annual risk of asbestos fiber in the ambient air of Karaj for all samples was in the range of 4.32 × 10-6 to 1.81 × 10-4 which in some places had more danger than the recommended risk range. According to the EPA guidelines, carcinogenicity acceptable levels are in the range of 10-4 and 10-6. Values higher than 10-4 have more carcinogenic risk and values lower than 10-6 have a lower carcinogenic risk.