Emission profiling of diesel and gasoline cars at a city traffic junction

Abstract In congested urban roads, cars must stop at intersections because of city traffic lights. As a result, pedestrians and traffic police personnel are exposed to pollutants emanating from the tailpipe of various vehicles at such city traffic junctions. In this study, various gasoline- and diesel-fueled cars complying with different emission standards were tested for their emissions in simulated city traffic junction conditions. The engine exhaust from these cars was subjected to physicochemical characterization at different engine speeds under no-load conditions. These engine conditions were chosen because the cars idle at different engine speeds at a city traffic junction. Gravimetric and real-time measurements were performed for the tailpipe exhaust sampled from these vehicles. Exhaust particles were collected on 47 mm diameter quartz filter papers and subjected to gravimetric analysis for determining the total particulate mass (TPM) and trace metals while the engines were operated at two different engine idling speeds, 1500 rpm (representing low idling) and 2500 rpm (representing high idling). At similar engine operating conditions, TPM and trace metals were lower for the exhaust from gasoline engines compared to the exhaust from diesel engines. Real-time measurements were performed for particle-bound poly-aromatic hydrocarbons (PAHs), particle number and size distribution, regulated gaseous emissions and smoke opacity of the exhaust at four different engine speeds, 1500, 2000, 2500, and 3000 rpm. Particle-bound PAHs showed a decreasing trend for the vehicles that complied with stricter vehicular emission standards. Higher particle peak number concentrations were observed for diesel exhausts compared to the results for gasoline exhaust. Regulated gaseous emissions were also compared.