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 μg m−3, respectively, in the dry season.