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ON-ROAD EMISSIONS OF PCDDS AND PCDFS FROM HEAVY DUTY DIESEL VEHICLES
Citation:
Gullett*, B K. AND J V. Ryan*. ON-ROAD EMISSIONS OF PCDDS AND PCDFS FROM HEAVY DUTY DIESEL VEHICLES. ENVIRONMENTAL SCIENCE & TECHNOLOGY 36(13):3036-40.
Description:
This work characterized emission factors, homologue profiles, and isomer patterns of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from on-road sampling of three heavy duty diesel vehicles (HDDVS) under various 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. The objective of the work was to improve our understanding of the effect of engine and operating conditions on PCDD/F emissions. 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. While these results may infer some condition-specific differences in PCDD/F emissions, the data ranges are not statistically distinct, suggesting that characterization of causal distinctions in PCD15/F emissions will require an extensive sampling effort. 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. Analysis of the emission factors, homologue profiles, and TEQ-related isomer patterns from this work and the tunnel work provide insights into comparative mechanisms and fleet representativeness.