The Maine Department of Environmental Protection issued an air quality alert for Friday, July 1, because of expected unhealthy ground-level ozone.

The DEP stated ozone is expected to be unhealthy for sensitive groups along the Midcoast, southwest coast, and high elevations of Acadia National Park.

Ozone levels have been rising in upwind areas on Thursday, according to the DEP. The ozone and its precursors are expected to move into the Gulf of Maine on Friday. During the afternoon hours, unhealthy for sensitive groups levels are expected along the coast from Kittery through Acadia Natational Park with the highest chance of an eight-hour average reaching unhealthy levels about midway between those regions.

Ozone is created when emissions from smokestacks and motor vehicles interact with sunlight. Much of the pollution is generated south and west of Maine and blown into the state on warm summer days.

Ozone is considered at an unhealthy level when it reaches 70 parts per billion or greater for an eight hour period. The nearest ozone monitoring station is at the Marshall Point Lighthouse in Port Clyde.

At elevated ozone levels, children, healthy adults who exert themselves, and individuals suffering from a respiratory disease such as asthma, bronchitis or COPD can experience reduced lung function and irritation. When this happens, individuals may notice a shortness of breath, coughing, throat irritation, and/or experience an uncomfortable sensation in their chest.

According to the DEP, people can adjust their schedules to avoid strenuous outdoor activity during the afternoon.