Thursday's weather forecast might create unhealthy conditions for people with breathing conditions, according to AirNow.gov, a national website that provides national air quality information.
According to the alert:
While high ozone levels are normally restricted to the warm season, fine particles can be high at any time of year. These pollutants arise from sources such as cars, trucks and power plants, with fine particle levels also enhanced by forest fires and residential burning.
Active children and adults, and people with lung disease, such as asthma, should reduce prolonged or heavy exertion outdoors.
To help reduce pollution levels, AirNow.gov suggests refraining from unnecessary driving and using public transportation if available.
The alert remains in effect until 11 p.m. Thursday.