Exploring the influence of human activities and the COVID-19 lockdown on urban air quality in Rajasthan, India

This study investigates the impact of anthropogenic activities and the COVID-19 lockdown on urban air quality across seven major cities in Rajasthan, India: Ajmer, Alwar, Jaipur, Jodhpur, Kota, Pali, and Udaipur. Spanning the period from 2018 to 2022, the research analyzes spatiotemporal variations in key air pollutants, including PM2.5, PM10, NO2, and SO2, across three distinct phases: prelockdown (Pre-LD), lockdown (LD), and postlockdown (Post-LD). The study utilized air quality data sourced from the Central Pollution Control Board (CPCB) and Rajasthan State Pollution Control Board (RSPCB), employing the Inverse Distance Weighting (IDW) method for spatial analysis and Pearson correlation for examining health impacts. The findings reveal a significant reduction in pollutant levels during the LD, with PM10 levels in Alwar decreasing by 66.74% in April and PM2.5 levels in Kota dropping by 62.02% in May. Conversely, a rebound effect was observed in the Post-LD phase relative to the LD period, with a 194.76% increase in PM10 in Alwar and a 171.28% rise in PM2.5 in Kota during the same months. The spatial analysis identified Jodhpur and Alwar as consistent hotspots for particulate matter pollution throughout all phases. A strong positive correlation (r = 0.93) between PM2.5 and PM10 underscores the dominance of fine particulate matter in the pollution profile. Furthermore, PM2.5 was positively correlated (r = 0.70) with cases of acute respiratory infections, highlighting significant public health risks. This study underscores the short-term benefits of reduced anthropogenic activities on air quality and the subsequent rebound effect following the resumption of activities. The results emphasize the necessity for sustainable urban policies, stricter industrial regulations, and enhanced public transportation to mitigate air pollution and its health impacts in urban areas.