Brick kilns, child respiratory symptoms and blood lead in Bangladesh: a national geospatial analysis of the 2025 Multiple Indicator Cluster Survey
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Background
Brick kilns are a major source of air pollution in Bangladesh. Their effects on child respiratory health and lead exposure have not been studied nationally with blood measures.
Methods
We linked a 2018 to 2019 satellite map of 6,978 kilns to the 3,149 displaced clusters of the Bangladesh Multiple Indicator Cluster Survey 2025. Exposure was the number of kilns within 5 km. Outcomes were cough and acute respiratory infection (ARI) symptoms in 23,357 children under 5 years, and venous blood lead in 10,622 children aged 12 to 59 months. We fitted survey-weighted modified Poisson models with district fixed effects. Diarrhoea and interview timing relative to the firing season served as negative controls.
Findings
Three in four children (75.4%, 95% CI 73.6 to 77.1) lived within 5 km of a kiln, and 20.3% (18.7 to 22.0) had ten or more. Exposure rose with wealth. Compared with no kiln, ten or more kilns were not associated with cough (adjusted prevalence ratio [PR] 1.05, 0.96 to 1.16), ARI symptoms (1.21, 0.90 to 1.62) or blood lead of 5 µg/dL or more (0.94, 0.85 to 1.03; crude PR 1.27, 1.14 to 1.41). Per 10 kilns, the ARI PR was 1.11 (1.01 to 1.21), but a spline showed no association (P=0.153). Cough was not associated with kiln density at the peak of firing (PR per 10 kilns 1.00, 0.96 to 1.05) but was in May and June (1.10, 1.04 to 1.17). The lead result held in all sensitivity analyses.
Interpretation
At survey resolution, living among more kilns was not linked to blood lead. Weak respiratory associations, absent at peak firing, fit confounding by place better than an acute effect of kiln smoke. Studies with exact locations should measure effects within 1 to 2 km of kilns.
Funding
None.
