Preterm births attributable to criteria air pollutant exposure in Bangladesh during 2015-2019.

Criteria air pollutant exposure impacts human health through various pathways. Preterm birth (PTB) is one of the major adverse birth outcomes (ABO) associated with such exposure. Although numerous global and regional studies have been conducted on this issue, few have recently investigated the impact of major criteria air pollutant exposure on PTBs in Bangladesh, one of the world's most polluted countries with the highest relative PTB rate. In this study, we retrieved high-resolution criteria air pollution data from recent studies and regionally scaled it to 10 km × 10 km resolution. We incorporated the MERRA-2 model, satellite measurements, and exposure-response modeling to quantify the impacts of CO, O, PM, SO, and NO exposure on PTBs in Bangladesh from 2015 to 2019. We observed the highest all-source CO, O, PM, SO, and NO exposure in 2018 at 272.8 μg/m, 88.2 ppbv, 62.9 μg/m, 20.5 μg/m, and 11.6 ppbv, respectively. These exposures were associated with 0.18 million [95% confidence interval (95%CI): 0.08-0.29 million] to 0.20 million [95%CI: 0.08-0.32 million] annual total PTBs among 4.3 million annual total live births, indicating an alarming 4.4-4.9% PTB rate exclusively attributable to the exposure to these five criteria air pollutants. Within these PTB estimates, our study found that combined CO, O, and PM exposure caused the majority (94.7-95.8%) of the total PTBs, with hotspots in the central and southern regions of Bangladesh. This study provides quantitative evidence of the PTB incidence caused by major criteria air pollutant exposure and discusses the urgency of the targeted reduction of pollutants as well as source control to reduce the risks of PTBs, which is critical for the overall well-being of the overpopulated and underrepresented women and children of Bangladesh.