A blanket of unhealthful air from a raging fire in Butte County covered the Napa Valley on Thursday, with health officials saying that some people should take precautions.
The thick smoke dropped ash on Napa and prompted worries that Napa County was on fire. Napa County's Office of Emergency Services (OES) said there were no Napa County wildfires Thursday.
The Bay Area Air Quality Management District issued an air quality advisory through Friday due to the Butte County fire, which had consumed more than 18,000 acres by Thursday afternoon, officials say. Butte County is more than 100 miles north of Napa.
The air quality in Napa is at unhealthful levels, Napa County OES said in a health warning. Children, older adults, and people with heart and lung disease should avoid all physical outdoor activity. Everyone else should avoid prolonged or heavy physical exertion.
If you must go outdoors and you are concerned about wildfire smoke, use an N95 respirator mask, OES said. These masks do not protect young children, officials added.