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Does driving less really impact air quality?

By Paul Nelson | Posted - Jan 23rd, 2014 @ 8:31am

SALT LAKE CITY — If we wanted to see a significant drop in air pollution in the Salt Lake Valley, how much driving would we need to cut out of our usual routines?

You may know that most of the smog you see in the sky comes from vehicles. But you might not know that most of those pollutants are emitted when a car is started when it's cold. Engines are adjusting their timing and catalytic converters are not filtering emissions as much as they would if the car was warmed up.

"That's not to say that once we're driving we should just keep driving, because there are emissions associated with that as well. But, again, the majority come from that cold-start cycle," said Bryce Bird, director of the Utah Division of Air Quality.

Chaining trips together can help a lot, Bird said. That way, we're not restarting a cold car when we're out and about.

He also said our daily commutes to and from work are not the biggest problem. Two thirds of every mile driven happen during the personal trips people make.


"One of the focuses is to skip trips. If we can even skip going to lunch after we've already driven to work, that will have a benefit," he said.

How much pollution can be kept out of the air if every person who works in the Salt Lake Valley found an alternative way to work?

"If everybody looked at either carpooling one day a week, telecommuting one day a week, or working a flexible schedule so they worked four 10 (hour days) and took a day off every week, just that act alone could take 2 to 3 percent of the emissions out of the valley," he explained.

Bird said this can add up with each day someone doesn't drive to work.

"When the inversion is in place, the lid is on the valley and everything we have accumulates until the next storm comes and cleans it out. So, yes, it is additive," he said.

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