Warming up cars during morning hours biggest contributor poor air quality, study shows

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SALT LAKE CITY - A study into vehicle emissions shows Utah drivers are contributing most to poor air quality before they even leave the driveway.

Students and researchers from Weber State University’s National Center for Automotive Science & Technology and Utah State University found cold starts contribute the most to a vehicle’s pollution than any other time during a trip.

“During the cold mornings, for the first two minutes is your highest pollution levels,” said NCAST director Joe Thomas. “About 75% of your total emissions of your total driving event.”

A cold start is defined as when the engine has been off for more than 12 hours. Thomas said the morning startup is the top polluter because the catalytic converter needs to warm up to function optimally, and that can’t be done while idling.

“You want to start the vehicle, and you just drive it,” Thomas said. “Let the vehicle warm up that way. It will reduce emissions in the long run.”

Bountiful mechanic Jay Hansen agrees. He said the idea of letting the car warm up for several minutes is a misconception. In reality, he said, it takes less than a minute.

“Ten, 15, maybe 30 seconds,” Hansen said. “It’s all just for creature comfort.”

Hansen said sometimes for older model cars, the time needed to warm up the catalytic converter is longer, but that’s typically only for cars older than 1986.

The NCAST study is one of several projects funded by the Utah Legislature looking at specific solutions to Utah’s air quality challenges. Thomas hopes the findings will urge drivers to make small changes to help the air quality situation.

For more information on the research being done at the NCAST, visit their website: http://www.weber.edu/ncast.


  • Bob of Bobs

    its my diesel, bought and paid for, and I will continue to warm up my vehicle for as long as I want

  • Corbin

    If I would have spent time to warm my truck up I would not have blown the engine. With the cold weather making oil thick it does not get to the top of your engine so starting and driving it right away will make your engine blow from lack of oil so I will be continuing to let my car warm up from now on.

    • Sherene

      You sound almost like a big brother jelous of his little brother’s fame. Your last name ‘s not Pruitt, is it?

      • Sherene

        Oh. Yea. I see your point. In any case,in the interest of preserving air quality, I only get around via unicycle or large goat, so none of this really applies to me. If you, Bob, Anotherbob, or Anyotherbob see me on the road, wave as you go by.

  • freewilltwo

    what about sitting at a red light for 5 minutes? no traffic coming from any direction, but we still have to sit there idleing, if its safe to do so, stop giving tickets for proceeding thru a red light!!!

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