Five-Year Fine Particulate Matter Assessment over a Western Indian Megacity

The variability of PM2.5 concentrations obtained from the air quality monitoring stations (AQMS) established at six different environments of the Pune Metropolitan Region (PMR), situated in the western part of India, is analyzed for the period 2014-2018. The PM2.5 concentrations showed an increasing trend at almost all locations within the city during the 5 years. Significant features observed were that the green/background location showed a declining trend in PM2.5 concentrations. However, the city's industrial area indicated an increase in PM2.5 concentrations over the years. The seasonal bivariate plot of PM2.5 showed that the winter season has the highest concentration, and also at low wind speeds a high concentration was observed, indicative of the local sources. Concentrated weighted trajectory analysis indicated that regional sources due to long-range transport also played a role in the PM2.5 mass concentration. The wavelet power spectrum of PM2.5 showed 2-4 day oscillations and 30-50 day oscillations associated with Madden-Julian oscillations.