Understanding of the relationship between air pollutants and meteorological parameters on the regional scale is a prerequisite for setting up air pollution prevention and control strategies; however, there is a lack of methodical investigations, particularly in the context of Bangladesh’s deficiency of information on air pollution. This study represents the first attempt to investigate the relationship between air pollutants (NO₂, O₃, SO₂, and CO) and meteorological parameters over Bangladesh using satellite data (OMI and MOPITT) during the period from 2015 to 2020. Geographically weighted regression (GWR) modelling was utilized to assess the relationship between air pollutants and weather variables. The spatial representation and average values of geographically varying coefficients showed that the column densities of air pollutants were affected by the meteorological parameters. For example, NO₂ was positively associated with temperature in most of the studied regions, with an average geographically varying coefficient value of 0.12 Dobson units (DU, 1 DU = 2.687 × 10¹⁶ molecules/cm²), indicating that NO₂ concentrations increase by 0.12 DU/year with every unit increase in temperature. The sources of NO₂ and SO₂ in Dhaka were identified through emission inventory analysis, and transportation and industry emissions were the most significant influencing factors for NO₂ and SO₂, respectively. Temperature and pressure showed a higher degree of relationship with all four air pollutants compared with other parameters. The results and discussion presented in this study can be of benefit for policy makers in developing air pollution control strategies in Bangladesh.

The past decade has witnessed remarkable economic development, marked by rapid industrialization and urbanization across Asian regions. This surge in economic activity has led to significant emissions, resulting in alarming levels of air pollution. Our study comprehensively assessed the spatial and temporal trends of key pollutants, namely nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and aerosol (using aerosol optical depth (AOD) at 550 nm as an indicator), from 2011 to 2021. The data sources utilized include OMI onboard the Aura satellite for NO₂ and SO₂, as well as MODIS onboard Terra and Aqua satellites for AOD. The results from spatial and temporal trend analyses of the three parameters show that there is a clear declining trend over China and Republic of Korea (e.g., NO₂ is declining with an overall rate of −7.8 × 10¹² molecules/cm²/year over China) due to the strict implementation of air pollution control policies. However, it is essential to note that both countries still grapple with substantial pollution levels, with proportions exceeding 0.5, indicating that air quality is improving but has not yet reached a safe threshold. In contrast, South Asian regions, including Bangladesh, Pakistan, and India, are experiencing an increasing trend (e.g., NO₂ is increasing with an overall rate of 1.2 × 10¹² molecules/cm²/year in Bangladesh), primarily due to the lack of rigorous air pollution control policies. The average emissions of NO₂ and SO₂ were remarkably higher in winter than in summer. Notably, the identified hotspots are statistically significant and predominantly coincide with densely populated areas, such as the North China Plain (NCP). Furthermore, this study underscores the pivotal role of sector-wise emissions in air quality monitoring and improvement. Different cities are primarily influenced by emissions from specific sectors, emphasizing the need for targeted pollution control measures. The findings presented in this research contribute valuable insights to the air quality monitoring and improvement efforts in East and South Asian regions.

Ground surface ozone (O₃) is an emerging concern in China due to its complex formation process. In August 2020, field measurements of O₃, NO_x, and volatile organic compounds (VOCs) were carried out in Hefei’s western suburbs. The pollution features of VOCs and O₃ formation were thoroughly analyzed. The total VOC concentration was 42.26 ppb, with the dominant contributor being oxygenated VOCs (OVOCs). Seven emission sources were recognized using the positive matrix factorization (PMF) model, including aged air masses, combustion sources, fuel evaporation, industrial emissions, vehicular emission, solvent utilization, and biogenic emission. Ozone generation mainly occurred under an NO_x-limited regime based on the zero-dimensional box model analysis. According to the scenario analysis, the 13% cut in O₃ might be achieved by the 10% and 30% reduction in NO_x and VOCs, respectively. The O₃ budget analysis demonstrates its high ozone production rate during the pollution period. The influence of regional transport cannot be ignored for high O₃ pollution. This paper provides scientific evidence for O₃ production and the strategies of reducing O₃ by controlling its precursors.