BTX (benzene, ethylbenzene, toluene and p-xylene) and meteorological parameters were measured in ambient air of an urban site located in Carmen City, Campeche, Mexico. A total of 412 samples were collected for BTX and analyzed by Gas Chromatography with Flame Ionization Detection (GC-FID). Meteorological parameters were measured by a portable station. A marked diurnal variation was found for all measured BTX. The highest concentrations occurred during midday (13:00-14:30 h). A clear seasonal pattern was observed too for all compounds registering their highest levels during summer sampling period. Mean concentrations for benzene, ethylbenzene, toluene and p-xylene were: 5.42, 3.97, 11.24 and 8.32 ppbv, respectively. BTX abundance showed the following order: toluene > p-xylene > benzene > ethylbenzene. BTX maximum concentrations were found when winds blowed from E and NE. Important oil industry sources and avenues are located at these directions. These sources could contribute to the levels of BTX in this site.

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