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Ozone air pollution worse, fine particle pollution levels best ever in DC-Baltimore-Arlington metro area, finds 2018 'State of the Air' Report

Baltimore County posts worst number of unhealthy days for ozone smog in 40-county metro area in three years, according to American Lung Associations 19th annual air quality report

(April 18, 2018) - WASHINGTON, D.C.

The American Lung Association's 2018 "State of the Air" report found that ozone air pollution in the 40-county Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area and throughout much of the Mid-Atlantic worsened when compared with last year’s report, even as fine particle pollution levels continued their steady improvement.  The "State of the Air" report gives results for three measures of air pollution—days with elevated ozone, and daily and annual values for fine particle pollution. 

The large metro area, centered in the District of Columbia and covering much of Maryland and Northern Virginia, for the sixth year met the current national standard for year-round particle pollution, according to the 19th annual "State of the Air" report. It also marked the 11th consecutive report in which the level for the worst county improved. Nevertheless, the metro area continued at 35th worst rank of 187 across the country.

For the fifteen cities and counties monitored for the daily measure of fine particle pollution, all posted passing grades, 10 of them with "A's" placing them among the cleanest in the country. For the first time the worst grade was as good as a "B," with the result that the metro area’s rank improved from 49th worst last year to 68th worst of 201 metro areas in the current report.

For ozone, 22 cities and counties were monitored, of which 14, notably in Maryland and in the immediate vicinity of the District, worsened.  Four grades dropped from passing marks to "F's," joining five others continuing at least five straight years with "F's."  Especially notable was that Baltimore County, Maryland, had 38 unhealthy days for ozone, the worst number in the metro area since the 2015 report. This was nearly twice as many as in the 2017 report, and included five days when the air quality was unhealthful for everyone, not only those in sensitive groups.  Not surprisingly, the metro area’s rank worsened from 32nd worst last year to 17th worst of 227 in the current report.

Compared to the 2017 report, the Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area has seen a distinct increase in unhealthy days for ozone and a continuing gradual improvement in both measures of particle pollution. This is in keeping with trends seen across the nation for both higher ozone and lower particle pollution levels than in last year's report. In the case of year-round particle pollution, the metro area posted its 11th consecutive improvement in its worst county’s level since the 2007 report, and for the daily measure, the area marked its 13th year in which the number of days with unhealthful air for the worst city or county was equal to or better than the previous report.

"The 2018 'State of the Air' report finds that unhealthful levels of ozone in the Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area put our citizens at risk for premature death and other serious health effects such as asthma attacks and greater difficulty breathing for those living with a lung disease such as COPD. As long as there are many days with high ozone levels, people with lung diseases such as asthma will continue to need medical attention," said Kevin Stewart, Director of Environmental Health, American Lung Association of the Mid-Atlantic. "Across the nation, the report found continued improvement in air quality, but still, more than four in 10 Americans – 133.9 million – live in counties that have unhealthful levels of either ozone or particle pollution, where their health is at risk."

The trends in this year’s report, which covers data collected by states, cities, counties, tribes and federal agencies in 2014-2016, confirm the ongoing challenges to reduce each pollutant in the changing political and outdoor climate.

"We can and should do more to save lives," Stewart said. "The American Lung Association in the District of Columbia calls on our members of Congress to defend the Clean Air Act, currently under threat from those who want to weaken this effective public health law. We also call on the U.S. Environmental Protection Agency to implement and enforce the law instead of trying to roll back major safeguards such as the Clean Power Plan and cleaner cars, both steps that help us fight climate change and reduce air pollution."

For 19 years, "State of the Air" has provided a report card on the two most widespread outdoor air pollutants, ozone pollution, also known as smog, and particle pollution, also called soot. The report analyzes particle pollution in two ways: through average annual particle pollution levels and short-term spikes in particle pollution. Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects such as lung cancer, asthma attacks, cardiovascular damage, and developmental and reproductive harm.

Ozone Pollution in the Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area
Compared to the 2017 report, the Baltimore-Washington-Arlington metro area experienced more unhealthy days of high ozone in this year's report.  After passing in last year's report, Fairfax County, VA and Anne Arundel and Charles Counties, and Baltimore City, MD posted "F" grades.  In addition to Baltimore County, MD's poor performance (ranking 30th worst of 768 counties nationwide), Harford and Prince George’s Counties, MD, Arlington County, VA and the District continued with "F" grades.  All nine of these jurisdictions had worse air quality for ozone than in the previous year.

Nevertheless, there were some bright spots:  Five counties (Calvert and Washington, MD, and Fauquier, Frederick, and Stafford, VA) matched their passing performance for ozone in last year’s report, and three (Montgomery, MD, Franklin, PA, and Loudoun, VA) earned "A" grades, placing them among the cleanest in the country. 

"Ozone especially harms children, older adults and those with asthma and other lung diseases," said Stewart. "When older adults or children with asthma breathe ozone-polluted air, too often they end up in the doctor’s office, the hospital or the emergency room. Ozone can even shorten life itself."

This report documents how warmer temperatures brought by climate change make ozone more likely to form and harder to clean up. This year’s report also revealed that ozone levels increased in most cities nationwide, in large part due to warmer temperatures in 2016, the second hottest year on record in the U.S. Over the past decades, ozone pollution has decreased nationwide because the nation has cleaned up major sources of the emissions that create ozone, especially coal-fired power plants and vehicles.

Particle Pollution in the Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area
The 2018 report also found year-round particle pollution levels were distinctly lower than in the 2017 report, and all were much better than the national air quality standard.  Even the metro area’s worst value (posted in Berkeley County, WV) represented that county’s ninth consecutive year of improvement.  Indeed, apart from Dorchester County, MD, all thirteen other counties or cities monitored for this measure showed improvement.  Nationwide, the best progress in this year’s report came in reducing year-round levels of particle pollution.

"Particle pollution is made of soot, chemicals, and tiny particles that come from coal-fired power plants, diesel emissions, wildfires and wood-burning devices. These particles are so small that they can lodge deep in the lungs and trigger asthma attacks, heart attacks and strokes, and can even be lethal," said Stewart. "Year-round particle pollution levels have dropped thanks to the cleanup of coal-fired power plants and the retirement of old, dirty diesel engines."

"State of the Air" 2018 also tracked short-term spikes in particle pollution, as these can be extremely dangerous and even lethal. According to the 2018 report, 10 counties had zero days when short-term particle pollution reached unhealthy levels in 2014-2016.  Seven of them (Anne Arundel, Baltimore, Dorchester, Harford, Montgomery, Prince George’s in MD, and Loudoun, VA) continued their streak among the nation’s cleanest counties for at least the 3rd straight year.  In addition, Howard County, MD moved to “A” from last year’s incomplete, and Frederick County, VA, and Berkeley County, WV, also joined the ranks of the country’s cleanest counties by moving from "B's" to "A's."  Washington County, MD bettered the metro area’s worst grade by improving from a long-standing "C" to a "B."  These improvements continue a general trend toward fewer short-term spikes in particle pollution in the Baltimore-Washington-Arlington metro area.

In other areas of the country, many of the daily spikes fine particle pollution were directly linked to weather patterns such as drought or to events such as wildfires, which are likely to increase because of climate change.  In some localities, high emissions from wood-burning devices have also been a factor.

While the report examined data from 2014-2016, this 19th annual report provides online information on air pollution trends back to the first report covering 1996-1998. Learn more about the District of Columbia rankings, as well as air quality in the Baltimore-Washington-Arlington DC-MD-VA-WV-PA metro area and across the nation in the “State of the Air” report at For media interested in speaking with an expert about lung health and healthy air, contact the American Lung Association in the District of Columbia Communications Director Ewa Dworakowski by calling 717-971-1123 or 717-503-3903 (cell) or emailing [email protected] .


About the American Lung Association

The American Lung Association is the leading organization working to save lives by improving lung health and preventing lung disease, through research, education and advocacy. The work of the American Lung Association is focused on four strategic imperatives: to defeat lung cancer; to improve the air we breathe; to reduce the burden of lung disease on individuals and their families; and to eliminate tobacco use and tobacco-related diseases. For more information about the American Lung Association, a holder of the coveted 4-star rating from Charity Navigator and a Gold-Level GuideStar Member, or to support the work it does, call 1-800-LUNGUSA (1-800-586-4872) or visit:

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