Correction: The original story incorrectly described the sanctions cities face if their ozone levels exceed limits under the Clean Air Act. They are not fined. The text has been corrected.
Bob Moon: Well, as Johnny Carson used to ask 'how hot is it?'
In many U.S. cities, July was the hottest month ever recorded, and August could match it. That means you'll see more red and orange on the weather maps -- and not just signifying the temperature -- but raising the alert for air quality.
From the Marketplace Sustainability Desk, Eve Troeh reports.
Eve Troeh: Here's one down side of the extreme heat across the country. News people are running out of things to say about it.
Diane Simmons:Quahog is suffering its worst heat wave in a century.
Tom Tucker: We now go live to Ollie Williams. How are you beating the heat, Ollie?
Ollie Williams: Swimming hole!
Tucker: Thanks, Ollie.
OK, so that's a fake newscast from the TV show Family Guy. But here's one metric the Environmental Protection Agency says bored weather men and women should add right now: air quality alerts.
Because on hot, sunny, stagnant days, the chemicals coming out of tailpipes, power plants and factories can get trapped in the air around us, rather than floating up higher.
Kara Brooks: It's just a very light haze that you can see.
Kara Brooks works for the City of Indianapolis. She's describing the look of ozone: a chemical compound that protects us when it's up high, but can make breathing hard when it's down low. When ozone levels rise, Indianapolis, like many cities, asks people to stay inside as a precaution. And to drive less, to reduce emissions.
BROOKS: Avoid rush hour traffic, use public transportations, avoid idling is possible, walk to lunch rather than drive, ride your bike.
Brooks says the voluntary Ozone Alert program is in the city's best interest. Under the Clean Air Act, the Environmental Protection Agency has to measure ozone levels. If cities go too high for a few years in a row, they can face mandatory pollution cuts.
Jonathan Levy at the Boston University School of Public Health says heat makes it difficult to promote health and cut pollution.
Jonathan Levy: Recommending that people spend more time in air-conditioned settings -- obviously the electricity has to come from somewhere. That could be power plants, and that could increase those emissions.
If summers stay this hot in coming years, ozone pollution will rise on its own. That means cities will have a harder time meeting environmental standards. One more headache in a heat wave.
I'm Eve Troeh for Marketplace.