The tree canopy at Pleasant Point Park in Buxton on Tuesday. The American Lung Association’s annual State of the Air report says ozone pollution remains a problem in southern and coastal Maine. Shawn Patrick Ouellette/Staff Photographer

The Portland region’s air quality got mixed reviews in a new national report on pollution levels, while the Bangor area continues to rank near the top for healthiest air in the United States.

The American Lung Association’s annual State of the Air report released on Wednesday shows that air quality in Cumberland County improved when measuring particle pollution, which is made up of fine and coarse particulates circulating in the air. The state’s most populous county had zero unhealthy days for particle pollution, according to the report, measuring from 2019-21.

Only two counties in Maine – Oxford and Aroostook – reported any unhealthy days for particle pollution over the three-year period, both reporting one day. All other counties had zero unhealthy days or there was insufficient data.

Ozone pollution remains a more significant problem in southern and coastal Maine.

Cumberland County, which is listed as the Portland region in the analysis, experienced a slight increase in ozone pollution compared to the previous report, with three days of unhealthy conditions in the 2019-21 time period. Hancock County reported five unhealthy ozone days, York four unhealthy days and Knox two unhealthy days. All other Maine counties reported zero unhealthy days for ozone air pollution.

Ground-level ozone is created by pollutants emitted from cars, power plants, chemical plants, refineries and other sources, according to the U.S. Environmental Protection Agency. Ozone pollution is typically worst on hot, sunny days in urban environments.


Penobscot County, represented in the national report as the Bangor metro area, did not experience any high-ozone days and “remains one of only seven cities in the nation that ranks on the cleanest cities lists.” Penobscot County has made the cleanest list for six consecutive years.

“As we can see from this year’s report data, there is much work to be done to improve our air quality,” said Lance Boucher of the eastern division of the American Lung Association. “Even one poor air quality day is one too many for our residents at highest risk, such as children, older adults, pregnant people and those living with chronic disease. That’s why we are calling on the Mills administration and the state Legislature to continue moving forward on policies to ensure that everyone has clean air to breathe.”

Nationally, the report shows air quality is improving overall, a trend attributed to Clean Air Act regulations. But, according to the report, more work needs to be done.

“Nearly 36% of Americans – 119.6 million people – still live in places with failing grades for unhealthy levels of ozone or particle pollution,” the report said. “Overall, this is 17.6 million fewer people breathing unhealthy air compared to last year’s report. The improvement was seen in falling levels of ozone in many places around the country, the continuation of a positive trend that reflects the success of the Clean Air Act.”


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