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Investigating The Temporal Variation in the Frequency of Smog Precursors in the Ambient Air of Lahore


 In present study the seasonal prevalence of smog precursors was analysed to investigate the temporal trend of smog formation in the ambient air of Lahore. Data set of three years (November 2017- April 2020) was obtained from compact ambient air quality monitoring station, installed by Environmental Protection Department on Jail Road, Lahore. Statistical analysis of dataset of smog precursors revealed that in winter, the concentration range of PM10, PM2.5, NO, NO2 was significantly higher than Punjab Environmental Quality Standards and WHO Air Quality Guidelines. Whereas in summer, tropospheric ozone recurrence was higher and showed significantly negative correlation with NO >PM2.5 >NO2 >SO2 and null association with PM10. Seasonal impact on smog precursors concentration was further approved by correlation analysis of weather component with air pollutants. According to statistical analysis, Ozone (O3) was found to have high positive correlation with temperature >wind speed >relative humidity >sunshine hour while inverse relation with air pressure while NO, NO2, SO2, PM2.5 showed positive corelation with air pressure and negative correlation with temperature, sunshine, and wind speed. These factual figures revealed that ambient air of Lahore has been experiencing reducive-type smog in winter which is acidic in nature and oxidative-type photochemical smog in summer since 2017.