Joint Iranian-Russian studies of airborne asbestos concentrations in Tehran, Iran, in 2017

Assessment of airborne asbestos in urban areas of Tehran is important due to its potential health risks posed by a significant excess of current standards. Determination of airborne fibers can be performed using Phase Contrast Microscopy (PCM) as well as such a modem technique as Facade pane and its spectrum (SEM). Since PCM cannot differentiate asbestos and non-asbestos fibers, SEM is recommended to monitor the airborne asbestos content. The objective of this study was to determine asbestos fiber concentrations in ambient air in different areas of Tehran. Following the collection of samples using standard methods, we determined all fiber counts using PCM and asbestos fiber counts using SEM with X-ray diffraction microanalysis. The study results were then compared to the data related to the past six years obtained from the Air Quality Control Company (Iran) conducting annual airborne dust measurements in residential areas of Tehran using PCM. It should be noted that the scope of activities of the Air Quality Control Company did not include differentiation of asbestos from non-asbestos fibers. According to the results, all airborne fibrous particles sampled were either organic or mineral fibers, the appearance and specter of which were different from those of asbestos. Filter loading with mineral and organic fibers as well as soot particles from automobile exhausts indicated generally high ambient air pollution at all sampling sites. Optical and electron microscopy analyses of five dust samples collected from horizontal outdoor surfaces detected no asbestos fibers. We recommend regular monitoring of ambient air pollution in the streets of Tehran at different seasons of the year and establishing asbestos fiber concentrations using scanning electron microscopy for complete characterization of air pollution.