A Bar Harbor resident who lives with allergies said the ozone makes it hard to breath.
“Breathing. I've always had respiratory issues so it makes it that much harder to breath when it's high,” said Douglas Graves.
He uses an app on his phone to keep track of the heat, humidity and air quality.
“I try to stay out of the heat,” Graves added.
Vehicle exhaust mixed with sunshine are the main cause of ground-level ozone, which can lead to breathing problems, a shortness of breath, or coughing especially for sensitive groups including those with asthma.
Elevated levels of ozone can also impact children and healthy adults who exert themselves, so the EPA suggests not doing strenuous work in the high heat.
On Monday afternoon, high levels of ozone were detected in New York City and the winds brought them to Maine, according to the EPA.
Visitors from Florida had never heard of an ozone warning.
“I never had a problem with ozone down there in Florida,” the husband said.
“No. As a matter of fact, I saw a sign at the campground about dangerous air and I wondered about it,” his wife added.
At the same time of the ozone warning, the National Weather Service has issued heat advisories for much of the state.
“We did not come prepared for this type of heat,” said Ann O'Leary, of California, who served as the senior policy advisor to Hillary Clinton in her 2016 presidential campaign. “I grew up here in Maine. I grew up in Orono. It's much hotter than I remember and we are drinking water. There is no air conditioning where we are staying so that's going to be hot, hot sleeping tonight.”