Abstract:
Air quality is an important environmental concern worldwide. National Environmental quality
standards are implemented by regulatory authorities to improve the air quality on the bases of
emission levels. US EPA defines 6 criteria air pollutants for the assessment of Air quality;
Nitrogen Dioxide (NO2) is one of them. The sources of NO2 include emission from vehicles,
power plants, lightening, soil emission etc. This study presents result of car MAX-DOAS field
campaigns (2014-2015) conducted along national highways of Punjab. Main objectives of the
field campaigns were to monitor NO2 concentration level within and around major cities, and
to identify the sources of NO2 emissions. Result showed that the concentration of NO2 varies
in these cities e.g. 75×1015 molecules/cm2 in Rawalpindi, 65×1015 molecules/cm2 in Lahore
and exceed the Pakistan National Environmental Quality Standards of 42.5 ppb. Furthermore,
car MAX-DOAS results were compared with OMI observations. Result showed that OMI
observations are largely underestimated especially over the urban centers of Punjab.
