Occupational Exposure Determination to Silica Dust in an Iron-stone Ore and Comparison with Standard

Introduction: Dust is one of the significant factors which cause occupational respiratory diseases among workers. Objective: The main purpose of this study was to determine the dust concentration, its silica percentage and comparison with standard. Method: This cross-sectional study was carried out at one of iron-stone ores in Southern Khorasan province. Air dust sampling was done using the NIOSH 7500 method and personal sampling pump with the cyclone in 52 stations in different situations of the mine. Total and respirable dust was determined by gravimetrical method. 5 bulk samples were taken for the determination of silica. Bulk samples determined with X-ray method and compared with standard. Result: Highest respirable dust concentration was measured in the extraction section (10.6 mg/m 3 ) and the lowest in the administration (4.02 mg/m3). Also, highest total dust concentration was measured in the crusher section (94.3 mg/m) and the lowest in the administration (16.6 mg/m 3 ). Average percentage of silica in the mine was 15.5%. Either measured respirable and total dust concentration was several times higher than standard concentration. Conclusion: Percentage of total and respirable dust in all parts of the mine according to the silica percentage was higher than the standard limit. Therefore, it’s required to reduce or eliminate workers exposure to silica by using engineering controls, administrative and personal protective measures.