Environmental impact of VOC emissions from motor vehicle gasoline and vapours: composition analysis and implications

Fuel composition and fuel type are crucial in determining the evaporative and combustion process emissions. This study examines the composition of Volatile Organic Compounds (VOCs) in the liquid fuel and headspace vapour of three commercially available regular and premium grade gasoline in India. More than 200 compounds were detected in the liquid samples, and 32 compounds were chosen as the target compounds based on the literature. The liquid normal grade fuel composition showed dominance of aromatics, accounting for about 50–64% of the total compounds, followed by isoparaffins (12–17%), paraffins (8–12%), naphthenes (4.5-6%), olefins (2–3%), oxygenates (5–8%) of the total detected compounds and others or unknown compounds. The premium gasoline showed higher concentrations of oxygenates and aromatics than the normal gasoline. Aromatics contributed 88% in the headspace vapour composition of premium grade and accounted for 86.9% of normal gasoline. VOCs are the primary precursors of ozone and secondary organic aerosols in ambient air; hence the environmental impacts like the ozone forming potential (OFP) and secondary organic aerosol formation potential (SOAP) of the target compounds were also determined in the study. The aromatics and paraffins showed the highest OFP and SOAP compared to the naphthenes and oxygenates. These results will aid in identifying the compounds that can be expected from fugitive emissions, define sources for receptor modeling, and determine the health and environmental risks associated with evaporative emissions.