Personal exposures to air pollutants and respiratory health among brick kiln workers and household members.

Background: Brick kiln workers (BKWs) may be exposed to high levels of respirable silica and other pollutants; however, few studies have measured personal exposures and health impacts in BKWs. We characterized exposures to brick kiln pollution and respiratory health among BKWs in Bhaktapur, Nepal.

Methods: We identified 64 brick kilns and selected a random sample of ten to conduct a household census and select a stratified random sample of 60 BKWs (makers, stackers, and haulers) aged ≥14 years with ≥10 years of kiln work, and household members aged ≥9 years. We measured personal exposures to kiln pollutants, and conducted sociodemographic and health questionnaires, spirometry, and chest imaging.

Results: We enrolled 88 participants (mean age 31.0±11.3 years, 77% male, 35% current smokers); 69% of 8-hour time-weighted average respirable silica exposures during work hours exceeded 25 μg/m3. Exposures were highest among stackers (117.9 μg/m3) and haulers (98.8 μg/m3) compared to makers (16.0 μg/m3). Work exposures to SO2 exceeded 2 ppm in 45% of stackers and 48% of haulers. All non-work hour PM2.5 exposures exceeded 15 μg/m3. While the prevalence of reported respiratory symptoms was low, 8% of participants had a post-bronchodilator FEV1/FVC ratio below the 5th percentile. We identified diffuse centrilobular nodularity and mediastinal lymph node calcification in 66% (19/29) and 24% (7/29), and 35% (9/26) with >15% of functional small airways disease on computed tomography. In contrast, none of the chest X-rays were consistent with silicosis.

Conclusions: Our findings highlight the need for occupational health interventions to protect brick kiln workers and residents from the effects of brick kiln pollution.