Measurements and analysis of criteria pollutants in New Delhi, India

Ambient concentrations of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and total suspended particulates (TSP) were measured from January 1997 to November 1998 in the center of downtown [the Income Tax Office (ITO) located on B.S.G. Marg] New Delhi, India. The data consist of 24-h averages of SO2, NOx, and TSP as well as 8 and 24-h averages of CO. The measurements were made in an effort to characterize air pollution in the urban environment of New Delhi and assist in the development of an air quality index. The yearly average CO, NOx, SO2, and TSP concentrations for 1997 and 1998 were found to be 4810 +/- 2287 and 5772 +/- 2116 mug/m(3), 83 +/- 35 and 64 +/- 22 mug/m(3), 20 +/- 8 and 23 +/- 7 mug/m(3), and 409 +/- 110 and 365 +/- 100 mug/m(3), respectively. In general, the maximum CO, SO2, N-x, and TSP values occurred during the winter with minimum values occurring during the summer which can be attributed to a combination of meteorological conditions and photochemical activity in the region. The ratio of CO/NOx (similar to 50) indicates that mobile sources are the predominant contributors for these two compounds in the urban air pollution problem in New Delhi. The ratio of SO2/NOx (similar to0.6) indicates that point sources are contributing to SO2 pollution in the city. The averaged background CO concentrations in New Delhi were also calculated (similar to 1939 mug/m(3)) which exceed those for Eastern USA (similar to 500 mug/m(3)). Further, all measured concentrations exceeded the US National Ambient Air Quality Standards (NAAQS) except for SO2. TSP was identified as exceeding the standard on the most frequent basis. (C) 2001 Elsevier Science Ltd. All rights reserved.