Assessment of Respirable Dust Exposure and Free Silica Percent in Small Foundries (Less than 10 Workers) in Pakdasht, 2011

Foundry workers are at risk of the silicosis; a disease caused by inhalation of dust containing free silica. The amount of silica in dust is important in developing the disease. In order to determine the occupational exposure limits (OEL)، it is important to measure the respirable dusts containing free silica. The aim of this study was to assess the exposure to respirable dust and the percent of free silica in small foundries in Pakdasht. In this study، we measured the amount of indoor free silica and respirable dust concentration during the casting activities. The respirable dust was gathered using the sampler pump and the cyclone. We used the gravimetry test to quantify the amount of respirable dust; and the colorimetric spectrophotometer method (Method 7601، National Institute of Occupational Safety and Health (NIOSH)) to measure the concentration of free silica. According to the NIOSH and ACGIH limits (0. 025 mg/m3)، fifty percent of workers were exposed to high concentrations of crystalline silica. The mean free silica exposure was 0. 04 12 آ±''> 0. 02 mg/m3. According to the PEL presented by the OSHA، the mean respirable dust concentration was high in all four processes in the foundries. The findings showed that fifty percent of workers were exposed to high amounts of the crystalline silica dust. It is necessary to control silica dust through various technical and management measures.