Air pollution is a vitally important public health hazard to Bangladesh, especially in the coastal areas where maritime shipping, industries and characteristic meteorological phenomena combine together to deteriorate the air quality. This study evaluates the spatial variability of PM₂.₅ and PM₁₀ in selected coastal regions of Bangladesh to identify pollution hotspots and assess compliance with World Health Organization guidelines and Bangladesh National Ambient Air Quality Standards. Measurements collected data from selected sites within the coastal area used a portable Air Quality Monitor, Indoor Outdoor Formaldehyde (HCHO) Detector (Model: B07SCM4YN3) and Garmin ETrex 10. Study found that PM₂.₅ between 51.2 µg/m³ in Patuakhali and 182.4 µg/m³ in Cox's Bazar, PM₁₀-values between (65.3 and 273.6 µg/m³). Comparison with the World Health Organization (WHO) air quality guidelines show that all sampled districts exceed WHO recommended limits for both pollutants by a large margin. Moreover, five districts did not meet national standards of NAAQS. Additionally, Cox’s Bazar shows the highest values which is 2.8 and 1.8 times higher than NAAQS standard level respectively and 7.3, and 1.8 times higher than WHO standard level respectively. Strong positive correlation between PM₂.₅ and PM₁₀ on general sources dominating for both size fractions. Differential exposure to maritime shipping emissions, proximity of sources (point and industrial), and geographical isolation from major pollution sources are proposed as potential key drivers for the observed spatial variation. Policy options focus on strict measures for controlling maritime emissions; improving industrial facilities and a district-level air quality management plan in line with WHO norms.
Keywords: Particulate matter; coastal air quality; spatial heterogeneity; WHO guidelines; Bangladesh standards.