Heat, pollution spur northern Utah 'red air' alert

The combination of hottest-day-of-the year weather and high levels of smog mean breathing outside today will be unpleasant. And for those with chronic respiratory problems, it's potentially dangerous.

It's a "red air" alert day along the Wasatch Front, but Sunday should be a whole lot better, depending on what time an expected cool front moves in, according to Bryce Bird, air standards branch manager in the Utah Division of Air Quality.

"Saturday's what we call an ozone action day. The chemicals that mix with heat and sunlight come from the urban lifestyle," he said. "The largest source is automobiles. So our main focus is to first let people know, if they're sensitive to air pollution, especially with impaired respiration, to stay indoors."

That means that "the very young, the active, the very old and anyone with chronic breathing problems" should avoid exertion outside from at least noon to 6 p.m.

People also need to know that they can make a difference to air quality by taking simple steps such as reducing the number of car trips they take. Combine errands or, better, ride your bike. Even foregoing mowing the lawn during a red-alert day can do a lot to reduce the mixture of chemicals that lead to ground-level ozone.

Smog, or ground-level ozone, is a reactive form of oxygen that results from a mixture of the chemicals. Air experts explain it with a math equation of sorts: nitrogen oxides plus volatile organic compounds (hydrocarbons) plus heat equal ozone. Vehicles are responsible for more than half the ozone. The three molecules, combined together, have an affinity to grab onto other molecules. Bird likens it to what you can see with old tires that begin to crack. That happens to the ozone and it attacks other things. "One thing it likes to attack is the lining of your lungs."

Air quality officials designate days that approach the limits of the federal air quality standard "Red Air" days. On those days, the ground-level ozone amount is likely to exceed national health standards set by the Environmental Protection Agency.

The highest pollution levels are felt between 2 p.m. and 8 p.m. May through September on hot, sunny days. And that's when it's particularly important for people who are ozone-sensitive to stay indoors.