Air pollutants are added in the atmosphere from variety of sources that change the composition of air and affect the biotic environment. The  concentration of air pollutants depend not only on the quantities that are emitted from air pollution sources but also on the ability of the atmosphere to either absorb or disperse these emission. The pollution concentration vary  spatially and temporarily causing the air pollution pattern to change with different locations and time due to changes in meteorological and topographical condition. The sources of air pollutants include vehicles, industries, domestic and natural sources. The presence of air pollutants in the ambient air adversely affects the health of the population. In order to prevent and control air pollution, the Air (Prevention and Control of Pollution) Act was enacted in 1981. The responsibility has been further emphasized under Environment (Protection) Act, 1986. It is necessary to assess the present and anticipated air pollution through air quality survey/monitoring programs. Therefore, Central Pollution Control Board had started National Ambient Air Quality Monitoring (NAAQM) Network during 1984 - 85 at national level and gradually the number of stations has increased over the years. The programme was later renamed as National Air Quality Monitoring Programme (NAMP).    The ambient air quality monitoring network involves measurement of a number of air pollutants at different locations in the country. Air quality monitoring requires proper selection of pollutants, selection of locations, frequency and duration of sampling, sampling techniques, infrastructural facilities, man power and operation and maintenance. The areas selected for monitoring are based on high traffic density, industrial growth, human population and its distribution, emission source,  public  complaints, the land use pattern etc. Generally, the basis of a network design are the pollution source and the pollutants present. The criteria pollutants measured are Suspended Particulate Matter (SPM), Respirable Suspended Particulate Matter (RSPM), Sulphur dioxide (SO2), Oxides of Nitrogen (NOx), and Carbon Monoxide (CO) etc.