Non-methane hydrocarbons in industrial locations of Bombay

Concentrations of non-methane hydrocarbons in atmospheric air are measured in areas close to five industrial locations in the city of Bombay during the period March 1993 to May 1994. Seventeen hydrocarbons, viz., ethane, ethylene, acetylene, propane, propylene, i-butane, n-butane, i-pentane, n-pentane, n-hexane, benzene, n-heptane, toluene, ethylbenzene, p-xylene, o-xylene, n-decane and identified in 260 urban air samples using a cryogenic preconcentration system and a Gaschromatograph with a flame-ionization detector. Analysis is done on packed columns: N-octane Poracil C column for the C2---C5, OV-101 column for the C6 and above hydrocarbons. A significant fraction of the C6---C10 hydrocarbons remains unidentified. About 44% of the samples collected in the Thane region of Bombay (with large number of chemical industries) and 50.8% of the samples collected in the Mahul region of Bombay (adjacent to two oil refining units) showed concentrations above 240 ppbv, which is the recognized air quality standard for zones with chemical industries by the Maharashtra Pollution Control Board. The concentrations of C6---C10 hydrocarbons were more than that for C2---C5 at the two industrial sites located at Thane region of Bombay, while the C2---C5 hydrocarbons were more at the Refineries area near Mahul, Bombay. Benzene concentrations are observed to be above 5.0 ppbv at four of the five chosen sites and its concentration was more than that of toluene. These studies indicate significantly higher ratios for some of the individual hydrocarbon to acetylene in air than corresponding autoexhaust values.