Abstract. Air quality deterioration, especially in urban areas is one of the most alerting problems of modern civilization. With the ever increasing vehicular traffic density, there is an increase in the emission levels of combustible products into the environment which is causing a continued threat to ambient air quality. The highest concentrations of PAHs are generally found in the urban environment due to increasing vehicular traffic and the dispersion of the atmospheric pollutants. Due to high density of population in cities, the risk associated with the human exposure to atmospheric PAHs is the highest. Seasonal trends were investigated to have higher PAHs concentration in winter and lower in summer. Increasing combustion activities and decreasing mixing height thought to be important factors for the observed high concentration of PAHs in winter period. Besides seasonal variation the daily variation in PAHs levels too were also studied and the PAHs concentrations were observed to be relatively high between 10 pm to 6am, which gives a proof of a relation with the limited day entry and movement of heavy vehicles in the city. The observations on air quality status predicts that most of the localities in Jaipur are experiencing the air pollution stress and the trend is likely to worsen in near future if proper control measures are not implemented. Vehicular exhaust is considered to contain various substances which are hazardous to human health. One key observation was that the mixture of these substances that had carcinogenic activities were fluorescent and by spectroscopy had similar fluorescence spectrum to polyaromatic hydrocarbons (PAHs). A number of PAHs were purified and their fluorescence spectra were examined.  The increasing respiratory diseases and hospitalization necessitate finding alternatives to improve the urban quality of life. Hence, there is a need to search for such an alternative fuel, which will enhances the quality of life and thereby protect the environment.

KEY WORDS: Vehicular Exhaust, Fluorescence, PAHs