Transboundary Air Quality Challenges in South Asia: A Comprehensive Analysis of Climatological Circulation Patterns and Implications for Bangladesh and Beyond

This article delves into the climatological circulation patterns in South Asia, specifically honing in on the Indo-Gangetic Plain (IGP) region, and examines their repercussions on air quality and public health in Bangladesh. The investigation scrutinizes the seasonal dynamics of air masses, aerosol plumes, wind components, boundary layer conditions, ground-level air particles, and gases. Employing reanalysis data from ERA5 and visualizing it with the Grid Analysis and Display System (GrADS) between 2015 and 2021, the study corroborates its findings using ground-level observation data from various sites in Bangladesh. Uncovering that Bangladesh faces deteriorating air quality in winter due to transboundary influences from the IGP and the far western regions, the study notes elevated aerosol and gas levels at the northern Rangpur site compared to Dhaka, signifying transboundary air pollution impact. Conversely, clean air from the Bay of Bengal sweeps over Bangladesh during the South Asian monsoon, benefiting the entire western IGP region. The research identifies local processes contributing to winter aerosol levels in Bangladesh, with transboundary pollution, notably from coal and post-monsoon crop burning in India, exacerbating air pollution. Utilizing statistical generalized additive modeling (GAM), the study discerns relationships between air pollutants and meteorological variables. It reveals the influence of CO and SO2 emissions on winter PM 2.5 levels, while wind speed and the planetary boundary layer (PBL) show a negative correlation with PM 2.5 concentrations during the monsoon and post-monsoon seasons. The findings underscore the significant impact of biomass burning and the PBL on Bangladesh's air quality. Considering Bangladesh and the Maldives as particularly susceptible to poor air quality consequences, the study emphasizes the urgency of targeted interventions and adaptive strategies in these regions. Notably, it pinpoints hotspots in the North Indian, Pakistani, and Afghan regions, introducing a geopolitical dimension to the study. This underscores the transboundary nature of the issue, stressing the need for cross-border collaboration in finding solutions. Additionally, the study connects seasonal circulation patterns and air pollution sources to implications for air quality and public health in Bangladesh, proposing mitigation strategies. It suggests leveraging the Malé Declaration (MALE) as a catalyst for collaborative efforts in mitigating transboundary air pollution across South Asia. In summary, the research not only contributes insights into Bangladesh's air quality but extends its implications regionally, laying the groundwork for a comprehensive and collaborative approach to address shared air quality and public health challenges in South Asia.