The role of local meteorology on ambient particulate and gaseous species at an urban site of western India

Dependencies of ambient concentrations of PM <inf>2.5</inf> , PM <inf>10</inf> , CO and O <inf>3</inf> on meteorology in Udaipur of India have been discussed based on the measurements from April 2011 to March 2012. PM <inf>2.5</inf> and CO were highest in winter due to lower PBL depth and calm winds while PM <inf>10</inf> and O <inf>3</inf> were highest in the pre-monsoon season due to convective activities. Lower wind regimes (<2 km hr ⁻¹ ), highest PM <inf>2.5</inf> and CO were 47 ± 20 μg m ⁻³ and 441 ± 170 μg m ⁻³ indicating the accumulation of pollutants while lower levels of PM <inf>2.5</inf> (36 ± 16 μg m ⁻³ ) and CO (317 ± 114 μg m ⁻³ ) indicated the impact of dispersion at higher wind regimes. A positive slope of ∆PM <inf>10</inf> /∆WS = 4.4 μg m ⁻³ /km hr ⁻¹ indicates predominance of natural sources of coarser particles. Higher concentrations of PM <inf>2.5</inf> and CO with correlation coefficient (0.42 and 0.52) under high RH and low temperature during winter season indicate the strong temperature inversion. Negative correlation between PM <inf>10</inf> and RH (r = −0.70) during monsoon indicates the role of rainfall in wetting the soil reducing its aerosolization and particle washout. Rainfall was significant for PM <inf>10</inf> (~53% reduction) than those observed for PM <inf>2.5</inf> and CO. Overall, this study suggests the strong influence of meteorology in the variation of air pollutants.