HEAVY-DUTY DIESEL PARTICULATE EMISSION FACTORS

For years, the Environmental Protection Agency measured particulate emissions from a variety of heavy-duty diesel engines through contracts with Southwest Research Institute. Particulate emissions samples were collected using an exhaust splitter to divert a fraction of the engine exhaust into a standard dilution tunnel. A small fraction of the diluted exhaust from the tunnel is pulled through a filter from which particulate mass and, in some cases, organic content of the particulate is determined. The sampling system and particulate emission factors that were computed from truck and bus fuel consumption data and average truck and bus speed data from New York and Los Angeles (freeway and nonfreeway usage in the USA) were discussed. Average particulate emission test results (steady state tests) for 2 stroke engines were 4.74 g/kg fuel and for 4 stroke engines were 2.64 g/kg fuel. Using average particulate emissions results, a particulate emission factor range of 0.8-1.3 g/km was computed. Nationwide diesel particulate emissions were calculated at 88,000 metric tons/yr.