Prerana Shakti and Ashutosh Kumar Pandey
Abstract
The present study investigated spatio-temporal variability of major air pollutants and their association with meteorological parameters in Jaipur and Jodhpur, Rajasthan, during 2018-2023. Results demonstrated pronounced seasonal variability, with pollutant concentrations highest in winter, followed by post-monsoon, pre-monsoon, and lowest during monsoon, due to wet deposition and enhanced dispersion. Jodhpur recorded higher concentrations (PM2.5: 35-150 ?g/m3; PM10: 90-300 ?g/m3) than Jaipur (PM2.5: 250-120 ?g/m3; PM10: 50-230 ?g/m3); NO2 and SO2 concentrations recorded 10-90 ?g/m3 and 6-18 ?g/m3 in Jaipur and 12-70 ?g/m3 and 5-35 ?g/m3 in Jodhpur, due to anthropogenic emissions. O3 exhibited strong photochemical behavior, ranging 20-100 ?g/m3 in Jaipur and 20-70 ?g/m3 in Jodhpur. Higher temperatures and wind speeds enhanced pollutant dispersion, whereas low wind regimes, shallow planetary boundary layers, and calm conditions favored pollutant accumulation; relative humidity showed an inverse relationship with most pollutants, reflecting washout effects during the monsoon. PM2.5 and PM10 were strongly correlated (r = 0.72-0.90), indicating anthropogenic sources. NO2 and SO2 showed moderate positive correlations with temperature (r = 0.48-0.64), suggesting enhanced photochemical reactions while negative correlations with humidity (r = -0.36 to -0.58), reflected washout and dilution effects. O3 correlated positively with temperature (r = 0.58-0.76) but negatively with primary pollutants, confirming its secondary photochemical formation. Regression results (R2 = 0.57-0.73) identified wind speed as a key regulators of pollutant dispersion. The necessity for season-specific mitigation strategies, strengthened monitoring frameworks, and climate responsive air quality management to minimize human exposure and support sustainable urban development in semi-arid regions.