U.S. Passenger Vehicle Fleet Dirtier After 2008 Recession

MTorrice writes The 2008 recession hammered the U.S. auto industry, driving down sales of 2009 models to levels 35% lower than those before the economic slump. A new study has found that because sales of new vehicles slowed, the average age of the U.S. fleet climbed more than expected, increasing the rate of air pollutants released by the fleet.

In 2013, the researchers studied the emissions of more than 68,000 vehicles on the roads in three cities—Los Angeles, Denver, and Tulsa. They calculated the amount of pollution released per kilogram of fuel burned for the 2013 fleet and compared the rates to those that would have occurred if the 2013 fleet had the same age distribution as the prerecession fleet. For the three cities, carbon monoxide emissions were greater by 17 to 29%, hydrocarbons by 9 to 14%, nitrogen oxide emissions by 27 to 30%, and ammonia by 7 to 16%.

Comments

Dirtier than a hypothetical, not an actual

[michaelmalak]

From the actual abstract:

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.

The article shows that the actual 2013 fleet is dirtier than the hypothetical 2013 fleet where the age distribution matches the 2007 fleet age distribution.

It does not show that the actual 2013 fleet is dirtier than the actual 2007 fleet. It's a question not addressed by this study, but I would be surprised if actual 2013 was dirtier than actual 2007.

Older cars reduce pollution

[Geoffrey.landis]

Exactly.
Manufacturing a car produces a significant amount of pollution. If the recession means that fewer cars were sold, and instead the existing cars were used longer, this would reduce pollution.
Unless this effect is accounted for, the headline here is meaningless.

from www.autolife.umd.umich.edu/Environment/E_Overview/E_Overview2.htm:
"Historian Mark Foster has estimated that “fully one-third of the total environmental damage caused by automobiles occurred before they were sold and driven.” He cited a study that estimated that fabricating one car produced 29 tons of waste and 1,207 million cubic yards of polluted air. Extracting iron ore, bauxite, petroleum, copper, lead, and a variety of other raw materials to process steel, aluminum, plastics, glass, rubber, and other products necessary to construct automobiles consumes limited resources, uses great amounts of energy, and has serious environmental repercussions."

see also:
http://www.theguardian.com/env...