Characterization of Spatial and Temporal Variation of Ultrafine Particles in a Highway Tunnel.
to traffic–related air pollution has been linked to increased risks of
cardiopulmonary disease, asthma, and reduced lung function. Ultrafine particles (UFP;
aerodynamic diameter ≤100 nm) may contribute to these increased health risks.
Previous tunnel studies have shown that UFP concentrations are highly elevated in poorly
ventilated tunnels compared to open–air mixed roadwa... read moreys; however, little work has
been done to characterize the seasonal and temporal variation of UFP in a roadway
tunnel. The goals of this work were to characterize UFP and other pollutant
concentrations along the length of an urban highway tunnel over the course of one year
and more intensely during two wintertime days to analyze seasonal and daily trends. The
study was done in the Thomas P. O'Neill Jr. Tunnel on Interstate 93 (I–93;
≥1.5x105 vehicles per day) in Boston, MA. Data was collected by driving the Tufts
Air Pollution Lab (TAPL) mdash; which measured particle number concentration (PNC, an
indicator of UFP) in the 6 nm to 225 nm size range, as well as CO, NO, NOx, PM2.5, PAH,
and black carbon — through the tunnel in each direction on 38 days distributed
over one year (Sept 2010 — Sept 2011), and then 45 times in each direction over
the course of two days (04:00 — 21:30) in January 2012. PNC was ~8–fold
higher in the tunnel than on the highway outside during the 12–month monitoring
campaign. In the northbound tunnel, the median PNC (particles/cm3) was 2.5–times
higher during the winter than the summer. Similar differences were observed in the
southbound lanes. In January 2012, median PNC inside the tunnel was higher in the
morning than evening. Results of this study could inform strategies for tunnel
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Civil Engineering.
Advisor: John Durant.
Committee: John Durant, George Allen, and Mary Davis.
Keywords: Atmospheric sciences, Environmental science, and Atmospheric chemistry.read less