Nitrogen Dioxide Monitoring In Urban Areas of Lahore, Pakistan

Nitrogen dioxide (NO2) plays significant role in atmospheric chemistry mainly in secondary air pollutants formation which consequently result in environmental acidification. It has adverse impact on human health and considered as the second most harmful air pollutant after PM10 in major cities of Pakistan including Lahore. In this study, 15 major urban sites of Lahore with respect to vehicular flow were focused during rush hours from 1:30 pm to 9:30 pm for the monitoring of NO2 level. Chemiluminescence technique was applied to identify NO2 concentrations by using Horiba APNA-370 monitor. For sampling, four months of winter season November 2016 to February 2017 were selected and measured monthly average mean values; associated meteorological conditions like temperature, wind speed, rainfall and relative humidity were also monitored. A spatial distribution map of different locations for NO2 concentrations was developed by using geostatistical tool ArcGIS. The highest NO2 values near the main roads were mainly due to intense traffic flow and vehicular emissions unlike residential and commercial locations. Moreover, the NO2 level exceeded the NEQS standards at most of the sampling points during study. Therefore, it is mandatory to take desired steps in order to develop effective mechanism to control air pollution before it becomes a serious hazard for human beings living in urban areas.