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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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Pacific 2001: Cassiar Tunnel Study — Particulate Matter Emissions Measurements
Lisa Graham and Cara-Lynn Gray
Environment Canada, Emissions Research and Measurement Division,
Ottawa, Ontario, Canada K1A 0H3
Steven Rogak, Thomas Brakel
University of British Columbia, Department of Mechanical Engineering,
Vancouver, British Columbia, Canada
Vehicle emission sampling was conducted at the Cassiar Tunnel in Vancouver during August 9-15, 2001. This was a 7-day study with 3 sampling periods each day. The goals of the Cassiar Tunnel Study were:
- To obtain accurate mass emission rates for a wide range of pollutants emitted from motor vehicles.
- To compare the emissions measured at the tunnel (>150,000 vehicles over 7 days) with chassis dynamometer measurements of a limited number of vehicles (70 vehicles over 5 weeks).
- To obtain current emission profiles for on-road vehicles for use in source apportionment studies.
One of the key unknowns in understanding ambient particulate matter concentrations, PM sources and the transformation processes is the relative importance of primary and secondary particles. The questions that must be answered in developing computer models to predict air quality are:
- How much of the ambient particle loading is due to primary emissions vs. secondary formation reactions?
- How large is the (on-road) transportation contribution to both primary and secondary particles?
- How much of the ambient particle loading is due to primary emissions vs. secondary formation reactions?
Measurements of PM10, PM2.5 and PM1 by cyclone for mass, OC&EC, ions, metals and speciated
organics were made along with particle size distribution and number concentration measurements. As part of the particulate matter measured at the tunnel comes from sources other than tailpipe emissions (e.g. tire wear, concrete or asphalt dust), an attempt was made to account for this re-entrained road dust contribution by the comparison of PM2.5 samples with additional PM10 and PM1 samples for mass, OC&EC and metals and by comparison to road dust samples collected inside the tunnel at the start of the study. Preliminary emission rate results will be presented for some of these PM species. Details of the implementation of the study will be presented, along with the use of a tracer gas to verify tunnel airflow measurements.