Northern California wildfires are pushing smoke into Fresno. How bad is the air quality?

Wildfires in the northern part of California are likely to affect the air quality in Fresno County and other parts of the San Joaquin Valley this week.

Multiple fires are burning in areas bordering the Oregon border, including Siskiyou, Trinity and Humboldt counties. The Redwood Fire in Tulare County could also add to the smoky air, the San Joaquin Valley Air Pollution Control District said Wednesday.

The district said an air quality alert was in place for Fresno, Madera, Merced, Tulare, Stanislaus and San Joaquin counties.

Air in Fresno County on Thursday morning was “unhealthy for sensitive groups,” according to the index. The chance for more effects from smoke was expected to rise as the day progressed, officials said.

“The District strongly urges the public to take health-protective actions to stay safe when smoke from wildfires affects the Valley,” the agency said in a news release.

The U.S. Air Quality Index advises people with heart or lung disease and older adults and children to protect themselves by avoiding strenuous activities and limiting outdoor activities. Also, use air filters and keep windows closed, the weather service recommends.

Particulate matter in the air can trigger asthma attacks, aggravate chronic bronchitis and increase the risk of heart attack and stroke, health officials warn.

The National Weather Service in Hanford issued a high wind warning for Wednesday afternoon and evening in the Bakersfield area, and a chance of thunderstorms in the afternoon in Tulare County.

For details on wildfires, go to the district’s Wildfire Resource page at www.valleyair.org/wildfires. To check air quality at any Valley location there’s myRAAN.com.

Current wildfires in Northern California

Map: NATHANIEL LEVINE | Sources: U.S. Department of the Interior, IRWIN, NIFC, NASA, NOAA and Esri

The Sacramento Bee contributed to this report.