Abstract:
Air quality is one of the major environmental concerns worldwide. Air quality
standards are implemented by regulatory authorities to maintain the air quality based
on criteria pollutants; Nitrogen dioxide (NO2) is one of them. It is a reddish-brown
gas with a pungent, irritating odour. It absorbs light and sometimes leads to the
yellow-brown haze seen over the cities - photochemical smog. NO2 is the only criteria
pollutant that has not been in control since the advent of air quality standards (US
EPA). The reason being the variety of NO2 sources i.e. vehicles, power plants,
lightening, soil emission etc. Rapid increase in vehicles on roads is the most
contributing source of air pollution worldwide. (Lundy et al., 2011, Han et al., 2006)
This thesis discusses the observation of first ever car MAX-DOAS field
campaign along National Highway 05 (N5-Highway) of Pakistan conducted during
November, 2012. Main objectives of the campaign were to measure NO2
concentrations along the Islamabad - Lahore segment of N5-Highway and to identify
the potential sources of NO2 emissions. Results showed that NO2 concentrations were
higher within major cities along the N5-Highway. The highest NO2 levels were found
around two major cities of Rawalpindi and Lahore i.e. 64.01 and 79.27 ppbv which
exceed the Pakistan’s National Environmental Quality Standards (Pak-NEQS) of 42.5
ppbv.
This study also presents comparison of NO2-VCD measured by Ozone Monitoring
Instrument (OMI) and car MAX-DOAS. The comparison reveals similar spatial
distribution of NO2 columns from both car MAX-DOAS and satellite observations.
However, the NO2 VCD retrieved from satellite observations are approximately an order
of magnitude lower than the ground based observations.
