You don't necessarily have to be an expert to know when the air quality is bad. Here's what you do: Go outside. If the temperature is high and the air is still - as in, you don't feel much of a breeze - it's probably better to go back inside, especially if you're sensitive to bad air.

You don't necessarily have to be an expert to know when the air quality is bad.

Here's what you do: Go outside.

If the temperature is high and the air is still � as in, you don't feel much of a breeze � it's probably better to go back inside, especially if you're sensitive to bad air.

On Monday, the Mid-Ohio Regional Planning Commission issued a smog alert under those very conditions, recommending that older adults, children and people with lung diseases such as asthma avoid "prolonged or heavy outdoor exertion."

According to the commission, an upper-level ridge of high pressure hung over the region and enhanced ozone formation, and southwesterly winds had dragged in regional pollutants as well.

This was the area's third smog alert so far this year, up from two during all of last year and none in 2014. That increase was expected, driven by a tighter federal threshold for allowable ozone levels, said Evelyn Ebert, the commission's air-quality program supervisor.

Monday's forecast called for the Air Quality Index to reach 105, which triggered the smog alert. The scale runs from 0 to 500, and air quality is considered acceptable as high as 100. The general population is thought to be affected starting at 151.

Tuesday should be better, Ebert said. The forecast called for an Air Quality Index of 67.

While you can't control the temperature or the wind, you � yes, you, the person who stepped into the still heat and went back indoors � can help to drive that number down, Ebert said.

And if you do it this month, you might earn some cash.

Mid-Ohio Regional Planning Commission, the Central Ohio Transit Authority, car2go and CoGo have teamed up for the Make Your Miles Matter Commuter Challenge, encouraging commuters to share rides, take the bus, walk or bike during the month of June.

Halfway through the month, more than 540 people have participated, organizers say, taking thousands of alternative trips and cutting more than 35,000 pounds of greenhouse gas emissions.

Participants � learn more at makeyourmilesmatter.com � can win daily prizes that include $20 Kroger and Target gift cards. Grand prizes range from a $500 cash card to free Chipotle for a year.

But the contest is about more than free burritos. Organizers want to cut into car and truck emissions, the biggest contributor to ozone pollution in Central Ohio, and raise awareness of other transportation choices, said Patty Olmsted, the commission's vanpool program developer.

"There's a lot of options these days to get around," Olmsted said. "So much more than 10 years ago."

@LoriKurtzman