Concentration, sources and health effects of silica in ambient respirable dust of Jharia Coalfields Region, India

Abstract

Background: The concentration of silica in occupational conditions is well defined and estimated around the world. Many countries in the world have developed air standards for occupational conditions based on the percent silica in ambient air. This is due to the pulmonary effect caused by silica yielding diseases like silicosis and pneumoconiosis. In India, occupational exposure to silica dust is regulated by Directorate General of Mine Safety (Tech.) (S&T) Circular No. 1 of 2004 Under Reg. 123 of Coal Mines Regulations, 1957 for any metal/non-metal mining operations estimated gravimetrically. As no silica standards are prescribed in India for non-occupational conditions, venturing into such analysis was well envisaged and perceived. Methodology: Air sampling was done at identified locations through high-volume samplers for 24 h, twice a week in pre-monsoon season (March to June) and the Whatman filter paper was sonicated at sufficient speed to isolate dust particles for energy dispersive X-ray. Results: The percentage of silica in “PM10” was found lowest in mining sites (15%), and highest in transportation sites (35%) and mid-value for mixed sites (24%). Thus, risk level gets magnified due to addition of finer dust generated in transportation and mixed sites than mining due to diesel driven vehicles. Burning of any fossil fuel generates high percentage of finer dust (< 2.5 µm). Conclusions: There should be proper prescribed standard for silica for non-occupational conditions.