Over the past month, Utah has already seen three days where the ozone concentration exceeded federal standards — a shockingly early start to a pollution problem that typically doesn’t hit its peak until July or August.

“I would predict that we are in for a bad ozone summer,” said Bo Call, a monitoring manager for the Utah Division of Air Quality.

The airborne pollutant, which can burn sensitive lung tissues when inhaled and is particularly harmful to children, builds up in the atmosphere on hot, sunny days. Temperatures along the Wasatch Front have averaged some 10 to 15 degrees above normal in the last two weeks, hovering in the lower 90s and creating ideal conditions for ozone formation as spring wraps up.

With the unexpected warm weather, the state busted the permissible pollutant levels, set by the Environmental Protection Agency, on May 25, June 1 and June 3. It’s likely that concentrations Monday, too, could exceed the standard. And it’s possible that 2018 could be the worst yet for ozone in Utah.

“It’s certainly not shaping up to be a great year,” Call added.

Ozone is not emitted directly but forms in the atmosphere when heat and sunlight trigger a reaction of chemicals in other pollutants, such as those released from car engines or lawnmowers. The result is a colorless, odorless gas that can cause coughing and shortness of breath.

In 2015, the EPA lowered the standard for the amount of ozone permissible at ground level, where humans might be exposed to it, from 75 parts per billion to 70 parts per billion after growing evidence suggested the pollutant was more harmful than previously considered.

Salt Lake City violated the new level 20 times in the summer of 2017. On Sunday, two different monitors — one at Hawthorne Elementary School and another in the Rose Park neighborhood — showed it crossed the acceptable threshold again for the first time this year.

Monica Traphagan, a meteorologist with the National Weather Service in Salt Lake City, doesn’t expect much improvement this week as the hot temperatures, little wind, few clouds and no rain continue. “I think the sense is that the summer will be warmer than average, as well, but it’s too early to say,” she said.

The ozone standards were also exceeded in late May and early June in Midvale, Roosevelt, Ogden and Harrisville. Any area, though, would have to break the standard at least four times to be in actual violation of the rules.

Officials recommend avoiding physical activity outside during the afternoon or limiting exposure entirely, particularly around 3 to 4 p.m. when ozone is likely be at its height for the day. They also ask residents to cut back on driving, carpool when possible and mow the lawn in the morning.