Data and methods

The survey for this study was implemented between January and February 2022, when the country experiences the highest levels of air pollution. The survey canvassed 12,250 individuals from 2,500 households, stratified across four sites reflecting the varying sources and levels of pollution: (1) persistent traffic,1 (2) major construction2 and persistent traffic, (3) brick kilns, and (4) comparator sites, across 100 primary sampling units (PSUs). Based on reported findings from Bangladesh’s Department of Environment (GoB 2018), the first two sites are located in the North and South Dhaka City Corporations (DCCs), while the brick kilns are located in the outskirts of the DCC area—these together represent the most polluted part of the country, as mentioned in chapter 1. The comparator is rural Sylhet, selected because it is one of the least polluted locations in the country (GoB 2018). Map 2.1 shows the locations of the PSUs across the sites. Areas in the outskirts of Dhaka covering brick kilns also include other factories and industries as well as the Siddhirganj power plant. Because the main source of air pollution in these areas is the brick kilns, the site has been named accordingly.

The sampling was designed to capture the range of varying pollution exposures and associated morbidities across each of the study sites.3 The selection of the PSUs was driven by the presence of points of interest (POIs) for each location. Adjacent PSUs are located at least 0.75 kilometers apart to minimize crossPSU contamination of pollutants to the extent possible. In each PSU, a listing exercise was carried out within a 0.25-kilometer radius of the POI to identify potential households to be included in the survey. The final list of 25 households from each PSU (25 PSUs per each of the study areas) were randomly selected based on stratification criteria set a priori.4 Appendix B, table B.1 shows the distribution of the sample.