Assessment of Environmental Impacts of Light-Duty Vehicle Dieselization

This report provides a first-level assessment of the environmental effects which might result if diesel vehicles in large numbers were produced and sold, thereby changing the mix of vehicles in the in-use fleet so that a substantial fraction were diesel-powered in future years. The study emphasizes the impacts of diesel exhaust emissions on air quality, especially particulates and odor. Impacts are projected to the year 2000, based on several selected scenarios for the growth in diesel population. Two types of air quality analyses are conducted; areawide and local site. The areawide analysis examines pollutant dump effects in three metropolitan city areas. The Local site analysis investigates pollutant concentrations in several critical urban sites: the heavily traveled freeway, the street canyon, and the enclosed parking garage. A general description of the methodology is provided. Results are presented in terms of trends in the emission inventories for the city-wide analysis and as pollutant concentration profile for the local site analysis. The areawide analysis indicates that dieselization would increase urban TSP by less than 3%, while air quality relative to HC, Co and NOx would improve. The local site analysis shows that dieselization would produce diesel particulate concentrations ranging from 9 to 13 micrograms/cubic meter at long term exposure locations in the freeway and street canyon sites and 24 micrograms/cubic meter in the enclosed parking garage. Odor effects in a nominal diesel-gasoline vehicle mix are found to be negligible.