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Long-Term
Efficiencies of Dust Suppressants to Reduce PM10 Emissions from Unpaved
Roads
John A. Gillies,
John G. Watson, C. Fred Rogers, David DuBois, and Judith C. Chow Desert
Research Institute, University of Nevada System, Reno, Nevada
Rodney Langston
and James Sweet San Joaquin Valley Unified Air Pollution Control District,
Fresno, California
Abstract
A 14-month study was undertaken to assess the long-term efficiencies
of four dust suppressants (i.e., biocatalyst stabilizer, polymer emulsion,
petroleum emulsion with polymer, and nonhazardous crude-oil-containing
materials) to reduce the emission of PM10 from public unpaved
roads. PM10 emission rates were calculated for each test section
and for an untreated section for comparison purposes. Emission rates were
determined from PM10 concentrations measured from 1.25 m to
9 m upwind and downwind of the road and above its surface. Calculated
emission factors ranged between zero and 1,361 g-PM10/vehicle
kilometer traveled (VKT)(average uncertainty = ± 35 g-PM10/VKT)
for the four types applied. One week after application, suppressant efficiencies
ranged between 33% and 100% for the four types applied. After 8-12 months
of exposure to weathering and 4,900-6,400 vehicle passes, the suppressant
efficiencies ranged from zero to 95%. Roadway surface properties associated
with low-emitting, well-suppressed surfaces are (1) surface silt loading
and (2) strength and flexibility of suppressant material as a surface
layer or cover. Suppressants that create surface conditions resistant
to brittle failure are less prone to deterioration and more likely to
increase long-term reduction efficiency for PM10 emissions
on unpaved roads.
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