This paper documents the ranges of mobile source air toxic (MSAT) emission factors produced by the U.S. Environmental Protection Agency's (EPA) MOBILE6.2 model due to changes in a variety of input parameters. These include calendar year, ambient temperature, fuel (gasoline) Reid vapor pressure (RVP), and vehicle speed. The variability of MSAT emission factors is more than an order of magnitude. They are most sensitive to changes in calendar year. For HC-based MSATs (i.e., acetaldehyde, acrolein, benzene, butadiene, and formaldehyde), significant decreases in emission factors can be realized by mitigating congested vehicle speeds. The variability is less for changes in temperature and changes in fuel RVP with moderate temperature. Emission factors for diesel particulate matter only change as a function calendar year and are not sensitive to changes in vehicle speed, temperature, or fuel RVP.
Samenvatting