Ambient monitoring of airborne asbestos in non-occupational environments in Tehran, Iran

Airborne asbestos fiber concentrations were monitored in the urban areas of Tehran, Iran during the period of 23 August to 21 September 2012. The airborne fiber concentrations of 110 air samples collected from 15 different sites in five regions of Tehran. The monitoring sites were located 2.5 m above ground nearby the main street and heavy traffic jam. The ambient air samples were analyzed using scanning electron microscopy (SEM), with energy-dispersive X-ray analysis and phase-contrast optical microscopy (PCM). The geometric means of the airborne asbestos fiber concentrations in the outdoor living areas was 1.6 × 10−2 SEM f ml−1 (1.18 × 10−3 PCM f ml−1). This criteria is considerably higher than those reported for the levels of asbestos in outdoor living areas in the Europe and the non-occupational environment of the Korea. No clear correlation was found between asbestos fiber concentration and the relative humidity and temperature. The SEM and PLM analysis revealed that all samples examined contained only chrysotile asbestos. It can be concluded that several factor such as heavy traffic, cement sheet and pipe consumption of asbestos, and geographical conditions play an important role for the high airborne asbestos levels in the non-occupational environments.