North Carolina logged its lowest ozone levels on record this year, state officials said Friday, because of favorable weather and lower pollutant emissions.
Charlotte was already on track to achieve its cleanest-air record since the 1970s, the Observer reported in September. Ozone, an irritating gas that aggravates breathing problems, peaks in summer.
The state broke the federal ozone standard only once this year, on May 15 in Winston-Salem. The previous record low was six days above the standard in 2009. The state has averaged 22 days a year over the standard in the past five years.
A cool, wetter-than-normal summer was a major factor, experts say. Ozone forms most readily on hot, sunny, still days.
But emissions from coal-fired power plants, a key source of nitrogen oxides, a major contributor to ozone, also have dropped.
Legislators cracked down on coal plant emissions in a 2002 law. By 2012, nitrogen-oxide releases from the power plants were down by more than 80 percent – a sharper reduction than the law required.
“These emission cuts, coupled with reductions from other industries and motor vehicles, have undoubtedly contributed to the improvements in ozone levels,” said Sheila Holman, director of the N.C. Division of Air Quality.
Earlier this month came word that the Charlotte metro area has officially complied with the federal ozone standard adopted in 1997. The area still hasn’t met a newer, tougher ozone standard set in 2008. The deadline to meet that standard is the end of 2015.
The American Lung Association this year ranked metro Charlotte’s ozone 19th-worst in the United States. The city ranked 10th-worst two years earlier.
Henderson: 704-358-5051; Twitter: @bhender