Variation in air quality at Filling Stations, Delhi, India, International Journal of Environmental Studies

The air was monitored for two consecutive periods, in the dry and the rainy seasons (2009–2010) at 40 petroleum-filling stations in the Indian capital, Delhi, to assess variations in carbon monoxide, nitrogen dioxide, PM10, PM2.5, benzene, toluene and xylene content. PM10 and PM2.5 concentrations exceeded the national ambient air quality standards at all the monitoring locations with maximum values of 1105 and 625 micro gm_3, respectively, in the dry season. At one location, carbon monoxide was found to be at as high a value as 7843 micro gm_3 in the dry season and crossed the national ambient air standard (2000 micro gm_3) at many locations. Benzene, toluene and xylene were present in very high concentrations in the dry season. Generally, all the air pollutants exhibited seasonal trends with higher levels in the dry season as compared to those in the rainy season.