Why There's More Ozone And High Pollution Warnings In The Summer

By Claire Caulfield
Published: Thursday, June 28, 2018 - 11:42am
Updated: Monday, July 2, 2018 - 4:14pm
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In the hot summer months, almost every forecast in Phoenix comes with an ozone or high pollution advisory.

Matt Pace, a meteorologist with the Arizona Department of Environmental Quality, said many people have the misconception that ozone and higher pollution levels increase with the temperature.

However, it’s the sunlight. When nitrogen oxides and volatile organic compounds from gasoline, car exhaust and industrial facilities interact with direct sunlight, it creates ozone.

Other summer conditions trap the pollutants in the Valley and exacerbate the problem.

“The high pressure sitting right over us, you get the calm winds you get the clear skies, you have a lot of sunlight and then, of course, that's going to mean that your ozone is going to increase,” Pace said.

High ozone and pollution advisories mean it’s dangerous for kids, older adults and people with respiratory diseases like asthma to go outside. For high alerts, it’s even unsafe to exercise outdoors.

Pace urges people to carpool, telecommute or take public transit on high-ozone days.

“Refuel after dark so you’re not emitting those VOCs,” he said.

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