T. Larson et al., LOCAL BACKGROUND LEVELS OF CARBON-MONOXIDE IN AN URBAN AREA, Transportation research. Part A, Policy and practice, 30(6), 1996, pp. 399-413
The objective of this study was to obtain a better understanding of ca
rbon monoxide (CO) concentrations immediately upwind of urban roadways
, the ''local background'' values, and how these concentrations depend
upon the surrounding traffic and the general meteorology. Measurement
s were made at seven sites in Seattle, WA during the winter of 1993. L
ocal background CO concentrations were characterized by an absence of
short term fluctuations, a steady buildup during the 3 p.m. to 11 p.m.
period, and a lack of spatial gradients in the 8-h average values. Di
stinctly different log-normal distributions of the 8-h averages were o
bserved for ''trafficked'' sites versus ''urban park'' sites, with mea
n values of 1.6 and 1.0 ppm respectively. A simple regression model wa
s developed to predict the local background CO that includes distance
from roadway, average daily traffic of nearby roadways, and the freque
ncy of occurrence of low windspeeds (R(2) = 0.74; F = 170). Copyright
(C) 1996 Elsevier Science Ltd