Spatio-temporal variations of asbestos fibres levels in ambient air of a densely populated and industrialized city of Iran

Abstract

ABSTRACTAsbestos fibre is one of the hazardous pollutants that may present in urban air. The aim of this study was to determine the concentration of asbestos fibres in the ambient air of urban areas of Isfahan, second industrialised and densely populated city of Iran, and to evaluate their spatial-temporal variation. Sampling was carried out from eleven points covering traffic areas of the Isfahan city during cold and warm seasons (winter and summer) in 2015. Scanning Electron Microscope (SEM) coupled to an energy dispersive x-ray (EDX) system was utilised to count and identify the asbestos fibres. Spatial mapping was carried out using the inverse distance weighting (IDW) method. Seasonal geometry meansof the concentration of airborne asbestos fibres in the studied regions were 14.48 ± 5 and 9.34 ± 4.90 SEM f/L in winter and summer, respectively, which was higher than the WHO guideline (2.2 SEM f/L‏).‏There was a significant correlation between the concentration of asbestos fibres and atmospheric temperature and humidity (p < 0.05). Also, the spatial distribution maps of asbestos fibres showed that the eastern area of Isfahan was more polluted than the western areas. Heavy traffic showed major contribution in the asbestos fibre emissions. Therefore, some effective course of actions such as traffic management, industrial replacement should be taken to regulate airborne asbestos fibres emission.