Dry winds that stoked the Golden State’s deadliest wildfires so far this year have shifted, bringing smoke and haze from Wine Country blazes to the Mother Lode today and prompting an air quality alert in Calaveras County.

The wind shift occurred Wednesday morning before 8 a.m. and some people on Highway 108 could see what looked like a fogbank rolling up out of the Central Valley to the west. The smoke prompted staff of at least one elementary school in Sonora to keep students inside Wednesday morning.

There’s a red flag warning for gusting winds, low humidities and critical fire weather through 5 p.m. Thursday. The warning area reaches up into the foothills of Calaveras and Tuolumne counties.

Dispatch personnel for Cal Fire’s Tuolumne-Calaveras Unit said there were no major fires burning in the Mother Lode region before noon Wednesday. All the smoke was coming from Wine Country fires.

There was a residential structure fire at 3:30 a.m. Wednesday in the Mountain Ranch area, and one resident was seriously injured, said Matt Brady with Cal Fire communications in San Andreas. Cal Fire assisted Central Calaveras Fire-Rescue Protection District personnel on the incident.

The Point Fire that burned four homes and 130 acres in the West Point area late Sunday and Monday was estimated to be 70 percent contained as of Wednesday morning, Brady said.

Strong dry winds blowing up to 50 miles per hour late Sunday stoked the firestorms that have killed at least 17 people, destroyed more than 3,500 homes and businesses and charred more than 160,000 acres so far this week in California.

Cal Fire staff say the Tubbs Fire in Napa and Sonoma counties has killed at least 11 people, making it the sixth-deadliest blaze in state history.

Statewide, fire crews were battling 22 large wildfires as of Wednesday morning. Emergencies have been declared in Napa, Sonoma, Yuba, Butte, Lake, Mendocino, Nevada, Orange and Solano counties.

Red flag conditions today and tomorrow will make work more difficult and dangerous for firefighters, and they will increase the risk of more wildfires, Cal Fire staff in Sacramento said.

Brad Banner, administrator for Calaveras County environmental management, sent out an air quality advisory shortly after 10 a.m. Wednesday. Air quality at lower elevations due to smoke from wildfires was described as “unhealthful for sensitive groups,” including anyone with heart and lung disease, infants, children, pregnant women and the elderly.

County health staff advise sensitive people to minimize outdoor activities or cease them altogether, especially exercise, and to stay indoors with windows and doors closed as much as possible.

“Do not run fans that bring smoky outdoor air inside,” Calaveras County health staff said in a statement. “Examples include swamp coolers, whole-house fans and fresh air ventilation systems. Run your air-conditioner only if it does not bring smoke in from the outdoors.”

They also recommend changing standard air conditioner filters to medium or high efficiency filters, and using a re-circulate or recycle setting on air conditioners.

While the air quality advisory is in effect, here are other tips from Calaveras County health and environmental management staff:

• Do not smoke, vacuum, fry food or do other things that will create indoor air pollution

• If you have asthma, take your medications and follow your asthma management plan

• Even healthy people can be affected by wildfire smoke. If you can see or smell smoke, take precautions.

• People with heart or lung disease who experience repeated coughing, shortness of breath, difficulty breathing, wheezing, chest tightness or pain should contact their doctors or clinics.

Dr. Dean Kelaita, health officer for Calaveras and Tuolumne counties, advises anyone with an existing illness that gets worse due to smoke exposure should seek medical help.

Contact Guy McCarthy at gmccarthy@uniondemocrat.com or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.