BANGOR, Maine — Bangor ranks as one of the cleanest cities for air quality in the country, but southern Maine residents are breathing in unhealthy levels of pollution, according to a new report released Wednesday.

Air quality has improved statewide, but unevenly from region to region, the American Lung Association’s 15th annual “State of the Air” report found. Covering 2010-2012, the report examined the two most widespread types of air pollution: ozone, the main ingredient in smog, and air-particle pollution, based on readings from official monitoring sites across the country that measure daily spikes and annual levels.

Particle pollution, sometimes called soot, can lodge deep in lung tissue and even pass into the bloodstream, contributing to a host of health problems. Ozone is a powerful respiratory irritant.

Five Maine counties — Penobscot, Androscoggin, Aroostook, Oxford and Sagadahoc — earned an A grade on the report card. Ozone levels were worse, however, in Cumberland County, which received a C, and in York and Hancock counties, which fared the worst with D grades.

The findings were split in Hancock County, which recorded nine unhealthy ozone days but ranked as the seventh-cleanest county nationwide for year-round particle pollution.

Nearly half of Maine residents live in counties with fair to poor air quality, the report found.

Bangor was among four cities nationally that recorded no unhealthy ozone days and scored well on short-term and year-round particle pollution. Last year, Bangor was one of 16 cities across the country considered the cleanest for particle pollution.

“I remember in the ’50s and ’60s you could get a breath of clean, fresh air,” said Dr. Paul Shapero, a local allergist and immunologist. “We’re trying to hold onto that in Bangor.”

Cumberland and York counties, meanwhile, recorded 14 days of unhealthy ozone levels over the three-year reporting period.

Ozone, a gas that occurs naturally in the atmosphere in small amounts, is fueled by emissions from cars and trucks, smokestacks, coal-fired power plants and chemicals such as paint fumes. Particle pollution consists of tiny specks of pollutants — from a wide range of sources including power plants, tailpipes and burning wood — that are suspended in the air.

High ozone levels can contribute to asthma attacks, poor lung function and other respiratory problems. Maine has one of the highest rates of asthma in the nation, with about 10 percent of adults and nearly 11 percent of children suffering from the chronic lung disease, according to the Maine Center for Disease Control and Prevention. Health experts suspect several factors contribute, including Maine’s location at the “tailpipe” of the nation, where environmental pollutants picked up on ocean and air currents stream in from urban areas. Four in 10 Maine households also heat their homes by burning wood, which releases harmful gases and particles into the air.

Less out-of-state pollution is expected to drift into Maine in the wake of a Tuesday Supreme Court ruling. The court’s justices upheld a federal regulation limiting emissions from power plants that blow downwind into the air above states along the East Coast.

Children, the elderly and those with lung or heart disease are most at risk from air pollution, Shapero said, as well as healthy adults who work or exercise outdoors.

“My family knows all too well the dangers of ozone pollution,” Erin O’Connor Jones of Scarborough, whose husband and three children have mild to severe asthma, said in a news release announcing the report. “High ozone levels can quickly turn a day at the beach into a day in the emergency room. I think all parents would agree that it’s time to put ozone standards in place that actually protect our children’s health.”

The U.S. Environmental Protection Agency is reviewing federal ozone standards, which agency staff report may fall short in protecting the public from harmful effects of smog.

Federal regulators previously estimated that lowering the standard from 75 to 60 parts per billion would save up to 12,000 lives, and prevent 21,000 hospitalizations, 58,000 asthma attacks and 5,300 heart attacks each year, according to the Lung Association. Lower ozone levels also would result in $35 billion to $100 billion in health and eco­nomic benefits by 2020, the association said.

Overall, the country’s air has gotten cleaner even as the population, energy use and miles driven have increased greatly, the report said. Still, nearly half the nation — more than 147 million people — live in areas with unhealthy pollution levels, an increase from last year’s report.

“While we can celebrate the continued reduction of year-round particle pollution across the nation, thanks to cleaner diesel fleets and power plants, we need to be doing even more to reduce ozone pollution,” Jeff Seyler, president and CEO of the American Lung Association, said in the news release. “Warmer temperatures create a breeding ground for ozone pollution and climate change amplifies the amount of air pollution and natural allergens we are forced to breathe.”

In Maine, four counties have no monitors for fine particles, while others monitor for only one of the two pollutants.

A separate report released in March awarded Maine high marks for both air and water quality. The report, prepared by the Maine Development Foundation on behalf of the Maine Economic Growth Council, awarded the state gold stars, noting progress toward recording fewer days of poor air quality for sensitive groups.

“A clean environment is vital to the people of Maine, who need healthy air and water, and to the industries that depend on Maine’s iconic natural resources,” Maine Department of Environmental Protection Commissioner Patricia Aho said in a Tuesday news release.

Jackie Farwell

I'm the health editor for the Bangor Daily News, a Bangor native, a UMaine grad, and a weekend crossword warrior. I never get sick of writing about Maine people, geeking out over health care data, and...