It’s the first day of summer, and Witt Lukas-Cordero is feeling it.

“I’ve noticed it’s harder to breathe, personally, spending more time outside,” he says. “I work outside, so it gets to be a lot harder by the end of the day. You can feel it in your chest.”

Another hot and hazy day in the metro with continuing air quality woes.

“Yeah, last week with the smoke, it was really obvious,” notes Ann Wasson, out with her dog Angel at Como Park. “You know about it, whether you were watching the news or not. But this one came as a surprise to me, but it makes sense, the weather as it is.”

Last week, the culprit was smoke from fires burning in Canada.

The Minnesota Pollution Control Agency says now, it’s ground level ozone – which is odorless and colorless – triggering conditions considered unhealthy for everyone.

“We’ve got a lot of heat, we’ve got air is a little bit dryer than we typically see this time of year,” David Brown, an air quality meteorologist with the MPCA, explains. “And then with that wildfire smoke still hanging around, we’re seeing the skies just a little bit hazy.”

That haze with fine particles still lingering from the smoke combined with the ozone can cause asthma symptoms, sore throats, and chest irritation.

“In the lungs it creates a spasm, and an inflammation of the airways,” explains Dr. Andrew Stiehm, a pulmonary medicine specialist with Allina Health. “So normally, the airways might be like a four-lane highway, and because of that irritation and spasm, it might shrink down to two lanes.”

Stiehm says the combination of ultraviolet light and heat, combined with particle pollution, react with oxygen molecules in the air we breathe.

“Some of the pollutants in the presence of heat and sunlight adding to the oxygen we’re breathing— and turning our oxygen dioxide into oxygen trioxide, which is ozone,” he says.

The MPCA says the ozone layer in the stratosphere protects us from ultraviolet radiation.

But ground ozone, the agency says, is a whole different story.

“The general public and healthy individuals might start to notice it a little bit- shortness of breath, tightness in the chest,” Brown says. “So, these sensitive groups, like children, the elderly and people with existing respiratory conditions, may be more significantly impacted.”

He hopes air quality conditions will be improved on Thursday.

Meanwhile, experts say the best way to prevent any issues is to restrict your time outside and avoid any strenuous activities.

Not an easy challenge for Minnesotans. “It seems like the air quality has been poor,” Lukas-Cordero says. “As much as we’ve been spending time inside, as Minnesotans, we spend six months inside. Hard to stay indoors when the sun is shining.”