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Average US Car Now Older, Resulting In More Air Pollution

Researchers at the University of Denver found that the US on-road freeway fleet age increased due to the global recession from 2008–2010. To put it simply, because consumers had less money available to purchase new vehicles, they hung on to the ones they owned, thus increasing the average age of vehicles being driven today.


There is an expected vehicle turnover for non-recession years that results in new vehicles entering the national fleet and older ones exiting. Older cars tend to emit more air pollution, so when consumers hang on to them and continue driving, more air pollution is generated.

The researchers captured vehicle data in Los Angeles, Tulsa, and Denver. Data for over 68,000 vehicles was studied.

They were able to quantify higher air pollution levels. “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 Recession of 2008 and Its Impact on Light-Duty Vehicle Emissions in Three Western United States Cities, Gary A. Bishop and Donald H. Stedman, is the full study.

The researchers determined that the mean age of the 2013 fleet was nine years. Another factor related to the recession was that many drivers drove less to reduce their fuel consumption and save money. So, even though the fleet increased in age, overall air pollution from vehicles might not have increased.

Interestingly, sales of Chevy Volts and LEAFs have done well even though they have faced challenging economic times. They still represent a tiny portion of the fleet, however. The LEAF produces no tailpipe emissions, of course, and Chevy Volts are in the same bolt most of the time, largely running on electricity.

As the economy continues its very gradual recovery, will consumers return to buying new cars with better emissions controls? Will sales of Volts, LEAFs, and Teslas grow?

Hopefully, most of the fleet will some day soon-ish be made up of low-emission, super-low-emission, ultra-low-emission, and zero-emission vehicles.

Image: Ifcaf, Wiki Commons

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