Determination of Nitrogen Dioxide in Ambient Air.

The major source of Nitrogen oxides (NOx) pollution is fossil fuel combustion in power station, industrial boilers and motor vehicle engines. During combustion, N2 in the air and nitrogen in the fuel are oxidized to NO. Nearly half of all anthropogenic NOx emissions come from mobile sources, the remainder coming from power stations and industrial boilers. Natural sources of NOx include volcanoes, bacterial activity forest fires and lightning. In the atmosphere, NO is rapidly oxidized to NO2 by ozone.

NO2 is considerably more toxic than NO, and most of the health concerns have been focused on NO2. NO2 can alter lung function and increase susceptibility to respiratory infections. Asthmatics, young children and individuals suffering from chronic respiratory disease may be particularly sensitive to NOx pollution. NO2 contributes to acid rain as it is easily converted to nitric acid (HNO3) in the atmosphere. Sodium Arsenite method are based on bubbling air into a solution followed by colorimetric analysis.