Exposure to respirable silica among clay brick workers in Kathmandu valley, Nepal.

Previous studies report high respirable silica exposures among clay brick workers globally; however, there are little data on exposures among workers in fixed chimney Bull's trench kilns, the predominant kiln type in Kathmandu valley, Nepal. We investigated respirable silica exposures among workers (N = 46) in five similar exposure groups (SEGs). Mean exposures were highest for red brick loading/carrying (331 μg/m3), followed by green brick stacking (223 μg/m3), fireman (102 μg/m3), coal crushing/carrying (92 μg/m3), and green brick molding (71 μg/m3). The average free silica content (13.8%) in the respirable dust fraction was similar to levels reported for clay brick workers employed in other types of kilns. Dust control measures and respiratory protection are recommended, with priority given to workers assigned to red brick loading and stacking and green brick stacking and carrying.