As thousands of people motor to Maine for a long Fourth of July weekend, air quality experts with Maine's Department of Environmental Protection are urging caution because of air quality.
A plume of ozone was expected to descend on coastal parts of the state from Kittery to Acadia National Park, coinciding with the arrival of a number of tourists.
"It can almost be like a sunburn on the lungs," said Martha Webster, an air quality meteorologist for Maine DEP.
"Even healthy people who are heavily exerting themselves become what we call a sensitive group," she added.
Beyond people planning something like a vigorous run -- children, the elderly, and people with asthma or bronchitis can be most affected.
According to Maine DEP, Rockland and places near it are expected to be most impacted by the ozone plume, which in the specified groups, can cause shortness of breath, coughing, throat irritation, and/or an uncomfortable chest sensation.
The risk is also expected to remain elevated until 11 p.m.
"Depending on how far the ozone travels down the coast, some of our coastal sites do not tend to peak until later in the evening," said Webster.
Fortunately, despite the ozone on Friday, there is some relief coming.
"I am not expecting any further issues with ozone for the remainder of the weekend," she said.