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The Recession of 2008 and Its Impact on Light-Duty Vehicle Emissions in Three Western United States Cities
journal contribution
posted on 2014-12-16, 00:00 authored by Gary A. Bishop, Donald H. StedmanThe
global economic recession of 2008–2010 severely depressed
light-duty vehicle sales in the United States. On-road fleets observed
with a remote vehicle exhaust sensor in 2013 at three historical sampling
locations in Denver, Los Angeles, and Tulsa showed large reductions
in the fleet fractions of 2009 model year vehicles of 40%, 38%, and
35%, respectively, when compared to prerecession 2007 levels with
the light-duty truck category suffering the largest percentage declines.
The fleet fraction for these ∼5 year old vehicles is normally
reserved for vehicles more than twice their age. This resulted in
a significant increase in the on-road freeway fleet age, which had
been relatively stable. The fleet average age increased by two years
in Denver and Los Angeles but only by one year in Tulsa, likely due
to its faster economic recovery. Using fleet fractions from previous
data sets, we estimated age-adjusted mean emissions increases for
the 2013 fleet to be 17–29% higher for carbon monoxide, 9–14%
higher for hydrocarbons, 27–30% higher for nitric oxide, and
7–16% higher for ammonia emissions than if historical fleet
turnover rates had prevailed.