> Research Highlight: ARL to Conduct Roadside Tracer Study for Regulatory Model Improvements
Research Highlight:
ARL to Conduct Roadside Tracer Study for Regulatory Model Improvements
Scientists from ARL's Field Research Division are preparing to
conduct a roadside barrier tracer study, anticipated to begin October 6
at the U.S. Department of Energy's Idaho National Laboratory. The
study, sponsored by the U.S. Environmental Protection Agency (EPA), is
designed to quantify the effects of roadside barriers (e.g., sound
walls) on the downwind dispersion of atmospheric pollutants emitted by
roadway sources (e.g., vehicular transport). In this study, ARL will
design a mock sound barrier and measure pollutant transport and
dispersion using an atmospheric tracer gas (sulfur hexafluoride-SF6) as
a pollutant surrogate. An identical tracer run will be conducted nearby
without a barrier for data comparison. The study will be conducted over
a wide range of atmospheric conditions during the day and at night.
Study results will inform an EPA regulatory modeling system called
AERMOD.
Background: AERMOD, developed through the American Meteorological
Society/Environmental Protection Agency Regulatory Model Improvement
Committee, incorporates air dispersion based on planetary boundary layer
turbulence structure and scaling concepts, including treatment of both
surface and elevated sources, and both simple and complex terrain. The
model, however, does not account for roadway pollutant concentration
adjustments if roadside barriers are present. This study is being
conducted under the newly formed NOAA/Idaho National Laboratory,
Meteorological Research Partnership, created in 2007 between the
Department of Energy and NOAA in a Memorandum of Agreement. EPA
strengthens this Partnership by becoming a supporting agency.
Significance: In recent years, studies have indicated that human exposure to air
pollutants in the immediate vicinity of large roadways is associated
with a range of health effects, including adverse respiratory effects.
Approximately 36 million individuals live within 300 feet of a four-lane
highway, railroad, or airport. NOAA's science will be used to help
guide the development of a new application of the AERMOD system that
will correctly determine the concentration of roadway emissions downwind
from roadside barriers. The study utilizes the world-class NOAA Tracer
Test Facility located at the Field Research Division in Idaho Falls,
Idaho.