York County's air quality has finally improved after three consecutive years of being listed among the 25 places in the nation with the worst air quality.

Dropping from 24th worst last year to 45th for long-term particle pollution in the American Lung Association's (ALA) 2012 State of the Air report, the York-Hanover-Gettysburg metro area showed the largest improvement of the three metro areas in the southcentral Pennsylvania region.

All seven counties - Cumberland, Dauphin, Lebanon, Perry, Adams, York and Lancaster - had improved results for annual particle pollution, helping to take southcentral Pennsylvania off of the "25 Most Polluted" list, but York had the most remarkable jump.

For bad ozone days, the York-Hanover-Gettysburg metro stayed at 45th worst, the same ranking it earned last year. York received an "F" for its number of bad ozone days, as did Dauphin and Lancaster counties.

Both York and Adams counties saw a decrease in the number of bad air days for short-term particle pollution.

Each of the counties in southcentral Pennsylvania either improved on the number of bad ozone days or stayed the same as last year.

York had a lower number of bad air days in terms of short-term particle pollution, but its national rank still went from 60th worst to 53rd. Cumberland County scored the region's worst grade with an "F" for short-term particle pollution.

Based on EPA index: The 13th annual scorecard ranks air quality based on a color-coded index developed by the EPA to alert the public of unhealthy air conditions. Grades are given to counties for ozone levels, year-round particle pollution and short-term particle pollution levels.

York ranked the 20th worst for annual average particle pollution in the 2009 State of the Air report, 25th worst in 2010 and 24th worst in 2011 before improving to 45th this year.

While the report shows the success the Clean Air Act has had in establishing standards for cleaning up such major pollution sources as coal-fired power plants, diesel engines and SUV's, some members of Congress still want to get rid of the law, said Deborah Brown, president and CEO of the ALA of the Mid-Atlantic.

"We must continue to fight for clean air and demand the full implementation of the Clean Air Act," said Brown.

The EPA estimates cutting air pollution through the Clean Air Act will prevent at least 230,000 deaths.

York's poor air quality could be related to the county's close proximity to the Baltimore and Washington corridor and to the coal industry in western Pennsylvania, said Kevin M. Stewart, director of environmental health of the ALA of the Mid-Atlantic.

Widespread concern: More than 40 percent of Americans live in areas where air pollution threatens their health, according to the ALA.

Ozone or particle pollution can cause wheezing and coughing, asthma attacks, heart attacks and even premature death. Infants and children, older adults, people who work outside and individuals with asthma, heart disease or diabetes are most at risk for being affected by poor air quality.

When you breathe particle pollution, you are inhaling a mix of chemicals, metals, aerosols, ash and diesel exhaust, Stewart said, and all of these can trigger asthma or heart attacks.

The results of the 2012 State of the Air report were collected from data from Jan. 1, 2008, through Dec. 31, 2010. Each annual report is from a three year span of data, Stewart said.

For more information about air quality and the ALA's work for clean air, visit www.stateoftheair.org.

- Reach Chelsea Shank at 505-5432 or cshank@yorkdispatch.com.