Characterization of VOCs from LPG and unleaded petroleum fuelled passenger cars

GAIA plot representing the spread of the OFP scales. •VOCs emitted from cars powered by unleaded petrol and liquefied petroleum cars were evaluated.•The ozone formation potentials of the VOCs were also estimated.•Multi-Criteria Decision Making Methods revealed the least polluting driving mode and fuel.•The benefit of each fuel depended on the VOCs emitted and their ozone formation potentials. The study monitored the emissions of volatile organic compounds (VOCs) from the exhaust of cars fuelled by liquefied petroleum gas (LPG) and unleaded petrol (ULP). Six cars, four fuelled by LPG and two by ULP, were tested on a chassis dynamometer at two different cruising modes of operation (60kmh−1 and 80kmh−1) and idle. A total of 33 VOCs were identified in the exhaust of both types of fuels by the use of GC/MS. Due to the complexity of the dataset, Multi Criteria Decision Making (MCDM) software PROMETHEE and GAIA was used to rank the least polluting mode and fuel. The 60kmh−1 driving speed was identified as the cleaner mode of driving as was LPG fuel. The Ozone Formation Potential (OFP) of the VOCs was also calculated by using the incremental reactivity scale. Priority VOCs leading to ozone formation were identified according to the three incremental reactivity scales: MIR, MOIR and EBIR. PROMETHEE was applied to assess the most preferred scale of reactivity for predicting ozone formation potential under different scenarios. The results enhance the understanding of the environmental value of using LPG to power passenger cars.