title: On-road emissions of PCDDs and PCDFs from heavy duty diesel vehicles.
abstract: This work characterized emission factors of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from on-road sampling of three heavy duty diesel vehicles (HDDVs) under experimental conditions of city and highway driving; idling operation; high (>400 ppm) and low (<5 ppm) sulfur (S) fuels; and high mileage and rebuilt engine testing. Emission factors, homologue profiles, and isomer patterns were compared to determine whether the experimental conditions had an impact on PCDD/F emissions, or whether these conditions were uninfluential in determining a fleet-representative emission factor. For a single HDDV tested under conditions of a high mileage engine, a newly rebuilt engine, and the newly rebuilt engine with low S diesel fuel, emission factors were 0.023 (+/- 0.022), 0.008 (+/- 0.002), and 0.016 (+/- 0.013) ng toxic equivalency (TEQ)/km, respectively. These results may infer some limited condition-specific differences in PCDD/F emissions, but these differences do not appear to have a significant effect on the HDDV emission factor. An older HDDV with mechanical fuel controls resulted in a single test value of 0.164 ng TEQ/km, significantly higher than all other results. Observed differences in emission factors, homologue profiles, and TEQ-related isomer patterns from this on-vehicle sampling and others' tunnel sampling suggest limitations in our present characterization of fleet PCDD/F emissions.
authors.affiliation: U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division, Research Triangle Park, North Carolina 27711, USA. gullet.brian@epa.gov
authors.forename: Brian K
authors.initials: BK
authors.lastname: Gullett
authors.forename: Jeffrey V
authors.initials: JV
authors.lastname: Ryan
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001572:Benzofurans / Q000032:analysis*; D000072338:Dibenzofurans, Polychlorinated; D004738:Engineering; D004784:Environmental Monitoring; D005742:Gasoline / Q000032:analysis*; D007536:Isomerism; D018986:Motor Vehicles; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D005742:Gasoline; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D001335:Vehicle Emissions