Assessment of airborne asbestos fiber concentrations in urban area of Tehran, Iran

Air quality in ambient outdoor air has seldom been evaluated in Iran. Accordingly, we evaluated airborne asbestos fiber concentrations in the urban environment of Tehran, Iran between January 2006 and March 2007. The airborne fiber concentrations of 80 air samples collected from 40 different sites in five areas of Tehran were analyzed by energy-dispersive X-ray analysis in combination with phase-contrast optical microscopy (PCM) and scanning electron microscopy (SEM). The geometric means of the airborne asbestos fiber concentrations were 3.4x10(-3) PCM f/ml (0.1 SEM f/ml) and 3.3x10(-3) PCM f/ml (0.20 SEM f/ml) according to areas and seasons, respectively. There were significant differences in the asbestos fiber concentrations between the areas and seasons (p=0.02; p = 0.04), respectively. In the areas, the average concentration was 3.4x10 (-3) PCM f/ml (0.1 SEM f/ml), which is considerably higher than those reported for the levels of asbestos in outdoor air in the USA and the urban environment of the Europe. The SEM analyses revealed that the fibrous particles consisted, approximately, of chrysotile (60%), tremolite (10%), anthophyllite (10%), and non-asbestos fibers (20%). We conclude that the high volume of traffic, industrial consumption of asbestos, and geographical and climate conditions are responsible for the high airborne asbestos levels in non-occupational environments in Tehran. Thus, it is to be expected that inhabitants of Tehran will suffer negative health effects due to exposure to asbestos airborne fibers.