A Code Orange air quality alert is in effect until 8 p.m. Friday for Mecklenburg and five surrounding counties.
Code Orange means ground-level ozone concentrations could approach or exceed unhealthy standards.
Children, active people, older adults and those with heart or lung disease such as asthma should limit prolonged or heavy exertion outdoors.
The N.C. Department of Environmental Quality in Raleigh issued the alert Friday morning for counties also including Cabarrus, Gaston, Lincoln, Rowan and Union.
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Code Red and Code Purple are the most severe alerts on the state’s air-quality index.
The Charlotte region reached well into Code Red territory on June 14, marking the region’s worst air since 2012. That’s when the area saw its last Code Red ozone day, along with 11 Code Orange days.
Friday should be sunny and hot, with a forecast high of 94.
Highs should reach 95 Saturday and 96 Sunday and Monday, before dipping to 91 on Tuesday, according to the National Weather Service in Greer, S.C.