Year (2024–25)-bound assessment of PM and Black Carbon variability over historic city in India: insights from ground-based measurements and satellite data

This study presents a year-bound assessment of ambient particulate matter (PM10, PM2.5, PM1.0), aerosol optical depth (AOD), and black carbon (BC) over Agra, a semi-arid region within the Indo-Gangetic Basin (IGB) and a major air-pollution hotspot. The study integrates ground-based measurements, satellite datasets, and advanced morphological characterization (FESEM-EDX) to evaluate seasonal and diurnal variations, meteorological influences, and aerosol composition. The annual mean concentrations of PM10 (160.3 µg m− 3), PM2.5 (90.7 µg m− 3), and PM1.0 (58.5 µg m−3) exceeded Indian NAAQS limits, indicating chronic exposure risks. Winter (Dec–Feb) showed peak pollution due to low boundary layer heights, thermal inversions, and increased biomass combustion, while monsoon (Jul–Sep) had the lowest levels owing to wet scavenging. Post-monsoon BC spikes are aligned with crop residue burning, and diurnal BC peaks reflected traffic and domestic activities. Satellite-derived aerosol optical depth (AOD) correlated with BC (r ≈ 0.64), although MERRA-2 underestimated short-term high-AOD events. FESEM-EDX analysis revealed seasonal shifts: mineral dust and quartz dominated in summer; soil organics increased during monsoon; and soot, fly ash, and secondary aerosols (S, N) prevailed in winter. Temperature showed negative correlations with PM and BC (r = –0.40 to −0.46), while high humidity enhanced aerosol growth in cold seasons. Wind speed negatively influenced pollutant levels, and wind rose analysis identified seasonal transport patterns. The study underscores the need for season-specific mitigation strategies and improved monitoring to identify and address both local and regional sources. Targeted interventions, such as controlling wintertime combustion, reducing post-monsoon biomass burning, and enhancing early-warning systems are recommended to reduce exposure. Strengthening satellite – ground integration will further support evidence-based air quality management in IGB cities.