Citation

Panda J. Indian Highw. 2000; 28(5): 11-17.

Copyright

(Copyright © 2000, Indian Roads Congress)

DOI

unavailable

PMID

unavailable

Abstract

This paper discusses the chemistry of photochemical smog, together with some possible approaches to reducing it on Indian roads. Photochemical smog is a major killer in India, especially where National Highways pass through residential areas in conurbations and other large cities. 60% of air pollution in Indian cities is due to exhaust emissions from cars. The major pollutants there are: (1) dust; (2) sulphur compounds (SO2 and H2S); (3) nitrogen oxides (NO and NO2); (3) carbon monoxide (CO) and carbon dioxide (CO2); and (4) hydrocarbons (HC). Some of these pollutants react chemically when they enter the atmosphere, to form even more harmful compounds. The pollutants and these additional compounds appear as gases, dust, smoke, mist, and fumes. Nitric oxide (NO) is responsible for several atmospheric photochemical reactions, especially in the presence of organic compounds, which produce additional pollutants. Sunlight, water vapour, carbon monoxide, aldehydes, and hydrocarbons contribute to further chemical reactions. The emission and dispersion of these pollutants depend on traffic volume and composition, speed, vehicle acceleration and deceleration, wind, and weather conditions. To reduce deaths, ambient air quality near roads should be predicted, so that appropriate management measures can be applied. Traffic and air pollution data should also be collected for a long period of time.