Assessment of occupational exposure to crystalline silica during demolition of buildings in Tehran

The term "crystalline silica", refers to crystallized form of SiO2 and quartz, as the most abundant compound on earth crust, it can causing silicosis and lung cancer at inhalation large doses in course of occupational exposure. Silica exposure is unavoidable during demolition of buildings and therefore it can result in many problems for demolition workers’ health the aim of this study was assessment of workers respiratory exposure with crystalline silica in during demolition of buildings in Tehran. In this study, in order to assessment of airborne crystalline silica exposure, four zone of Tehran (west،east،south،center) selected. Samples were collected on mixed cellulose filters, by using filter holder at flow rate of 2 l/min for a maximum volume of 800 liters. After the transferring the samples to laboratory then in order to analysis of samples, Visible absorption spectrometry (at 420-820nm) was used according to the "National Institute of Occupational Safety and Health" (NIOSH) method No. 7601 higher average of exposure crystalline silica with geometric mean of 0/185 mg/m3 was related to south area، and center area with GM 0/085 mg/m3 have lowest exposure with crystalline silica. 48 sample (80%) of total sample were above the standard for crystalline silica (ACGIH0/05mg/m3). The geometric mean of worker's exposure to crystalline silica was in the range of 0/085-0/0185 mg/m3. regarding to 80% of total of sample was above the threshold limit value (0/05mg/m3). And exposure with crystalline silica during demolition of building unavoidable, this necessitates control of emission of dust during demolition.