Measuring in-cabin school bus tailpipe and crankcase PM2.5 : a new dual tracer method

Ireson, R. G. and Ondov, J. M. and Zielinska, B. and Weaver, C. S. and Easter, M. D. and Lawson, D. R. and Hesterberg, T. W. and Davey, M. E. and Liu, L. J.. (2011) Measuring in-cabin school bus tailpipe and crankcase PM2.5 : a new dual tracer method. Journal of the Air & Waste Management Association, Vol. 61, H. 5. pp. 494-503.

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Official URL: http://edoc.unibas.ch/dok/A6002270

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Exposures of occupants in school buses to on-road vehicle emissions, including emissions from the bus itself, can be substantially greater than those in outdoor settings. A dual tracer method was developed and applied to two school buses in Seattle in 2005 to quantify in-cabin fine particulate matter (PM2.5) concentrations attributable to the buses' diesel engine tailpipe (DPMtp) and crankcase vent (PMck) emissions. The new method avoids the problem of differentiating bus emissions from chemically identical emissions of other vehicles by using a fuel-based organometallic iridium tracer for engine exhaust and by adding deuterated hexatriacontane to engine oil. Source testing results showed consistent PM:tracer ratios for the primary tracer for each type of emissions. Comparisons of the PM:tracer ratios indicated that there was a small amount of unburned lubricating oil emitted from the tailpipe; however, virtually no diesel fuel combustion products were found in the crankcase emissions. For the limited testing conducted here, although PMck emission rates (averages of 0.028 and 0.099 g/km for the two buses) were lower than those from the tailpipe (0.18 and 0.14 g/km), in-cabin PMck concentrations averaging 6.8 microg/m3 were higher than DPMtp (0.91 microg/m3 average). In-cabin DPMtp and PMck concentrations were significantly higher with bus windows closed (1.4 and 12 microg/m3, respectively) as compared with open (0.44 and 1.3 microg/m3, respectively). For comparison, average closed- and open-window in-cabin total PM2.5 concentrations were 26 and 12 microg/m3, respectively. Despite the relatively short in-cabin sampling times, very high sensitivities were achieved, with detection limits of 0.002 microg/m3 for DPMtp and 0.05 microg/m3 for PMck
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Former Units within Swiss TPH > Environmental Exposures (Liu)
UniBasel Contributors:Liu, Lee-Jane S.
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Air & Waste Management Association
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 Nov 2012 16:22
Deposited On:08 Nov 2012 16:12

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