Wildfires causing hazardous air in Placer County. Here are the latest readings, forecasts

The Mosquito Fire burning in the Tahoe National Forest near Foresthill is causing poor air quality throughout much of the Placer County foothills. Some densely populated suburbs may have smoky air later today.

The latest air quality readings at 9 a.m. Wednesday showed the air in Auburn was “very unhealthy,” according to the federal air quality index. That means people with heart or lung disease, older adults, children and teens should avoid physical activities outdoors. All others should avoid strenuous outdoor activities and consider canceling outdoor activity.

Very unhealthy air is spread across Auburn, North Auburn, Penryn, Cool and areas north of Interstate 80.

So far, the air quality in Rocklin, Lincoln and Roseville remains “good,” according to monitors. But smoky air near the ground is being observed in eastern Rocklin and northeast toward Grass Valley, said Sierra Littlefield, a forecaster with the National Weather Service.

The smoky air is expected to shift northeast into higher elevations of the Sierra this afternoon and into the evening, Littlefield said. But smoke “will funnel back into the valley locations” around midnight and air quality could worsen in eastern Roseville and Placerville. The smoke is not expected to be as dense in those communities as what Auburn is experiencing.

“It will be a mix around of who gets to deal with the smoke,” Littlefield said.

The Mosquito Fire has burned more than 800 acres since it broke out Tuesday evening in mountainous terrain along the Placer and El Dorado county border. The deputies in Placer and El Dorado counties have issued mandatory evacuations in some areas.

The air quality in Sacramento was good at 9 a.m. However, the air is forecast to be unhealthy for sensitive groups both later today and Thursday as the region enters another day of a record-breaking heat wave.

This story was originally published September 7, 2022 at 10:31 AM.