Ozone pollution is expected to be at unhealthy levels in the Charlotte region Thursday, state forecasters say.
The Code Orange forecast means children, seniors and people with respiratory or heart conditions should avoid strenuous exercise. A similar forecast was released for the Raleigh-Durham-Chapel Hill area.
Charlotte and the state have seen ozone levels fall in recent years as industries such as coal-burning power plants and motor vehicles improved their emissions.
The Environmental Protection Agency announced this summer that all of North Carolina was in compliance with all air standards for the first time since 1997.
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Ozone levels have exceeded the federal standard on only two days in the state so far this year. No days broke the standard in 2014.