This study was conducted to estimate the contribution of vehicular exhaust gases towards ambient air quality in Lahore, Pakistan during 2017. LANDCOM-III flue gas analyzer was used for determination of vehicular exhaust pollutants (CO, SO2, NO2, NO, H2S, HC) for five vehicles groups (motor bikes, Qingqi rickshaw, local cars, imported cars and public transport vans) from April to September, 2017. Major pollutants were compared with their National Environmental Quality Standards (NEQS) for the country. Ambient air quality was monitored using Haz scanner HIM-6000 during smog formation in the city in October and November, 2017. From the study, it was concluded that except local and imported cars, all vehicles groups emit high concentration of pollutants as compared to the standard values. It is also observed that public transport vehicles i.e. Qingqi rickshaw and vans contribute more towards atmospheric pollution as compared to other vehicle groups in the city. During smog formation in the city, PM2.5 and PM10, NO, NO2 (NOx) concentration was decreased whereas concentration of O3, H2S and VOCs increased in November than October. Ozone concentration during the smog was below NEQS indicating that smog was not totally photochemical smog but mainly originated from vehicular and industrial exhaust gases.

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