The CT site is located at 49 17' 01.9 N and 123 01' 54.2 W, at 40 m above |
sea level (a.s.l.). The tunnel is used mostly by light duty traffic with peak
traffic volumes at rush hours. The goal of measurements at this site was to
reduce the uncertainty in mobile source inventory for gas and particle
emissions from light duty traffic sources, emphasizing the emissions of the
precursors to PM formation and primary PM emissions for comparison with
tailpipe emissions data from traditional testing conducted in laboratory on
mobile source emissions, particularly for mass emission rates and chemical
profiles. Duration of the emission study was from August 3rd to 10th, 2001.
For several measurements, different sampling and analytical techniques were
used as a check on the accuracy of the measurements. For most gas measurements,
two sets of instruments were deployed, one at each end of the tunnel, whereas
most of the PM measurements were conducted at the exit end of the tunnel. Gas
measurements included the typical pollution gases (SF6 as the tracer, NOx, N2O,
CO, CO2, methane, SO2, VOCs, carbonyls, organic acids, NH3, Graham and Gray,
2002). The PM chemical and physical properties were measured in great details.
For physical properties, particle number size distributions from 10 nm to 3 um
were measured, and hygroscopic properties were measured at two sizes (Prenni et
al., 2002). Chemical measurements characterized the
mass, inorganic and carbonaceous compositions of the primary particles.
More information can be found in Li (2004), the Pacific 2001 Special Issue in