Comparison of regulated and PM_2.5 EC/OC emissions from light-duty gasoline, diesel and CNG vehicles over different driving cycles

Understanding source contributions to ambient atmospheric particulate matter (PM) and toxic chemical pollution is critical to the development of effective mobile source emission control strategies. In this part of a larger PM source apportionment study, motor vehicle exhaust was characterized for eighteen light-duty vehicles driven over four driving cycles on a chassis dynamometer. Vehicle emission testing was conducted from July 2005 to May 2006 and included eleven gasoline vehicles, one gasoline-electric hybrid, two compressed natural gas (CNG) vehicles, and four diesel vehicles. Primary gaseous emissions of total hydrocarbons (THC), CO, NO_x, CO₂, as well as PM_2.5 (PM with aerodynamic diameter less than 2.5 microns), PM_2.5 elemental and organic carbon (EC/OC), polycyclic aromatic hydrocarbons (PAHs), and potential molecular markers, such as hopanes and steranes, were measured. Presented here are comparisons of regulated emissions, CO_2, and PM_2.5 EC/OC from gasoline, CNG, and diesel vehicles. Detailed molecular level analysis of PAHs and marker compounds will be presented elsewhere.