TEMPORAL DYNAMICS OF AIR POLLUTANTS IN SMOGGIEST LAHORE

Abstract Temporal prevalence of air pollutants, responsible smog precursor and influencing meteorological parameters were investigated in the ambient air of Lahore, fourth smoggiest city of the world. For statistical analysis, data set of three years on air quality parameters was obtained from Air Quality Monitoring station (CAAQMS) located on Jail Road, Lahore. According to the results, monthly concentration range of PM10, PM2.5, NO, NO2 in every winter was significantly higher than PEQs and WHO-AQGs whereas the tropospheric ozone was higher in summer but below standard limits. While Mann-Kendall test and Sens-slop estimator showed non-significant declining slope of PM10(SSE=-3.729μg/m3), PM2.5(SSE=-1.408μg/m3), NO(SSE=-1.318μg/m3), NO2(SSE=-2.459μg/m3), SO2(SSE=-1.672μg/m3) over the entire study period. Whereas 60% AQI values of PM2.5 were responsible for unhealthy smoggy winter. Upwinds only from northwest of Lahore, where Sheikhupura Industrial Zone, heavy vehicular traffic and agricultural lands are dominant emission sources, contributes in winter season of Lahore. Furthermore, NO, NO2, SO2, PM2.5, PM10 were high in winter due to significantly high (r ≥ 0.7) air pressure and low (r ≥ -6) temperature, sunshine, and wind speed while ozone was profoundly high in summer due to (r ≥ 0.8) high temperature >wind speed >relative humidity >sunshine hour and low air pressure. These findings suggest that meteorological conditions significantly affect the temporal prevalence of air pollutants in Lahore. Particulate matter (PM2.5) is major cause of acidic smoggy winters while the emissions from upwind areas contribute in worsening the smoggy winter every year .Therefore, Government require a spatio-temporal emission abatement plan to combat with smog consequences.