Charlotte might not violate a more stringent ozone air-pollution standard the federal government announced Thursday, an achievement that would reverse a decades-long trend.
The Environmental Protection Agency on Thursday set a new standard of 70 parts per billion, down from the current 75 ppb limit that metro Charlotte officially achieved only in July.
Compliance with the standard is based on a rolling, three-year average. Mecklenburg County’s current average is 68 ppb, but readings from 2014 through 2016 will determine whether it meets the new standard.
“While we currently comply and our air quality has been getting better, a final determination will depend in part on the values in 2016,” said county air quality director Leslie Rhodes.
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Ozone forms in hot, sunny weather. The invisible gas afflicts people with respiratory diseases, such as children with asthma, and can worsen heart and lung diseases.
The air across North Carolina has been growing cleaner because of state and federal initiatives that cracked down on emissions from motor vehicles and power plants, two key contributors.
Locally, Rhodes credits a program that has funneled $4 million in grants to replace old, dirty-burning diesel engines with new ones and an ongoing campaign to urge people to take alternative forms of transportation. Motor vehicles are a key source of pollutants that form ozone.
Mecklenburg County recorded two days this year above the current ozone standard, but none in either of the two previous years. In 2014 metro Charlotte dropped off the American Lung Association’s annual list of the nation’s smoggiest cities for the first time in 15 years.
“We’re trending in the right direction,” said Terry Lansdell, program director of the Charlotte-based advocacy group Clean Air Carolina.
Advocates had argued for a new standard of as low as 60 ppb. With EPA’s decision, Lansdell said, “we don’t think it does enough to protect public health.”
Legislation this year to reduce the number of air monitors across the state, he said, could stall the recent improvements.