Assessment of occupational exposure to the respirable fraction of cement dust and crystalline silica

Exposure to respirable fraction of cement dust and its crystalline silica content is the most important occupational risk factor in cement industries requiring more evaluation and monitoring. This study aimed to assess exposure to crystalline silica and cement dust among workers of a cement industry in Saveh city, Iran. In this cross-sectional study, 62 samples of respirable dust were collected from breathing zone of the workers in different sections of factory. Determination of respirable fraction of cement dust concentrations carried out using gravimetric method according to the NIOSH method no. 0600. Visible absorption spectrophotometry was used according to the NIOSH method no. 7601 to determine crystalline silica content of respirable dust samples. The highest exposure concentrations to respirable fraction of cement dust was observed in the Raw Mill and Cement Mill, and the lowest exposure in Administrative Department and Kiln the range of workers exposure in the production sites were 1.77 to 18.89 mg/m3. The range of workers exposure to the crystalline silica in the production sites was 0.011 to 0.104 mg/m3. The highest and lowest mean of exposures was observed in the raw Mill and cement mill respectively. Occupational exposure to the crystalline silica in 57% of site samples exceeded adjusted TLV recommended by NIOSH and Iranian of Occupational Health Technical Committee (0.05 mg/m3). The average of free SiO2 fraction in whole site samples was 1.17% varying from 0.49% in the cement Mill to 1.53% and 1.7% in crusher and Kiln sections, respectively Levels of exposure to cement respirable dust in all productive sections were significantly higher than the adjusted TLV. However, in administrative and control departments it was lower than the TLV level. Regarding crystalline silica, levels of exposure only in “Raw mill” and “kiln” were significantly higher than the adjusted TLV. Highest exposure concentrations to respirable fraction of cement dust recorded in Raw Mill and cement mill, and exposure to crystalline silica in raw Mill, Crusher and kiln, Therefore, preventive measures should primarily be targeted at these units.