Determination of Airborne Concentration and Type of Asbestos Fibers in High-Traffic Areas of Zahedan City

Asbestos fibers are one of the hazardous air pollutants in high-traffic areas of cities. This study was conducted during summer 2016 with the aim of determining the concentration and type of asbestos fibers in the air of high-traffic areas of Zahedan, Iran.

In this descriptive, cross-sectional study, 4 high-traffic and 2 traffic-free areas of Zahedan were chosen. Ambient air samples were collected according to the NIOSH 7400 method, with a flow rate of 2 l/m and 4 hours per day. The asbestos fiber in the samples were analyzed with the use of Phase-Contrast optical Microscopy (PCM) and Scanning Electronic Microscopy (SEM).

The mean and standard deviation of asbestos contamination density in high-traffic areas were 0.0012 (0.0004) f/cc and 0.0012, respectively, which were higher than the threshold limit value (TLV). In traffic-free areas with mean and standard deviation of 0.0003 ± 0.0003 f/cc the asbestos concentration was lower than the allowed limits. To check the normality of data Kolmogorov-Smirnov test was used (p< 0.05). The results of Kruskal-Wallis test showed that there is a meaningful difference between the means of the two measured groups (p< 0.001). The types of asbestos fibers based on EDS spectrums and electron microscope images were actinolite, tremolite, and chrysotile.

The findings of the present study indicated that the concentration of asbestos fibers in the sampleswas higher than the WHO standards for ambient air (0.00005 PCM f/ml). The use of asbestos fibers in car brake and clutch, as well as in asbestos cement sheet and insulation in buildings are among the most important sources of air pollution in the city.