Long-Term Assessment of Ambient Air Quality, Meteorological Influence, and Transboundary Transport in a Tier-II Indian City
摘要
This study investigates annual and seasonal variations in ambient air pollutants—PM10, PM2.5, NO2, and SO2—at ten monitoring stations across Agra city, India, from 2017 to 2024. The stations include key locations such as Taj Mahal, Rambagh, Shah Jahan Garden, and Nunhai. The annual average concentrations ranged from 15.45 to 142.39 µg/m3 (PM2.5), 46.54–235.47 µg/m3 (PM10), 4.55–46.69 µg/m3 (NO2), and 0.86–33.02 µg/m3 (SO2). PM10, PM2.5, and NO2 consistently exceeded national ambient air quality standards, while SO2 remained within permissible limits. Seasonally, PM concentrations peaked during winter and were lowest in the monsoon, with PM2.5 reaching up to 482 µg/m3 and PM10 up to 883.34 µg/m3. Seasonal variations in SO2 and NO2 were minimal, possibly due to constant sources of emissions such as traffic and industry. The results of the exceedance factor analysis indicated that the most critical pollutant was PM2.5. There was a significant influence of meteorological parameters such as temperature, precipitation, humidity, wind speed and direction over the dispersion of pollutants. The air mass flows were predominantly from the northwest and northeast, indicating transboundary pollution predicted by HYSPLIT back-trajectory modelling. The study highlighted the inadequacy of the existing monitoring network and spatial heterogeneity among monitoring locations. Overall, this research provides a flexible framework for sustainable air quality management in secondary cities and aligns with SDG 11 and SDG 13 by supporting climate-sensitive urban planning, public health resilience, and data-driven policy interventions.