Gaseous Air Pollutants and Respirable Crystalline Silica Inside and Outside Homes at Brick Kilns in Bhaktapur, Kathmandu Valley, Nepal

Household and ambient air pollution remain public health problems in much of the world. Brick kiln employees in Nepal may be particularly at risk of high air pollution exposures and resulting health effects due to high levels of outdoor air pollution, substandard housing, and indoor biomass cooking. We conducted a cross-sectional study of indoor and outdoor air pollution concentrations at workers’ homes at four fixed chimney Bull’s trench brick kilns in Bhaktapur, Kathmandu Valley, Nepal. We measured air concentrations of carbon monoxide (CO), carbon dioxide (CO(2)), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), and respirable crystalline silica (SiO(2); cristobalite, quartz, tridymite) using established methods and conducted a survey about characteristics of homes or samples that may be associated with air pollution concentrations. Geometric mean concentrations of CO, CO(2), and SiO(2) (quartz) were 0.84 ppm, 1447.34 ppm, and 6.22 µg/m(3), respectively, whereas concentrations of all other air pollutants measured below lower detection limits. Most characteristics of homes or samples were not associated with air pollution concentrations. We found a positive association between the variable how long lived in house and SiO(2) (quartz) concentrations, which may reflect sustained take-home exposure to SiO(2) (quartz) over time. Interventions should focus on administrative controls to reduce take-home exposure to SiO(2) (quartz) in this population.