Flames from the Rim Fire in the hills behind Tuolumne City, Calif., on Wednesday.
That red area is where the air will be "unhealthy" on Thursday, and likely for days to follow, because of the Rim Fire.
The massive "Rim Fire" around California's Yosemite National Park is now about 30 percent contained and it's hoped that cooling temperatures and more moderate winds will continue to work in firefighters' favor.
But The Associated Press cautions that officials say it will likely still be three weeks before the fire is surrounded and that the blaze likely won't be out until many weeks after that.
According to the online "fire tracker" that our colleagues at Southern California Public Radio's KPCC are maintaining, as of Thursday morning more than 192,000 acres had been burned. About 111 structures had been destroyed and 5,500 others were threatened. Fortunately, only 4 people had been injured and there had been no fire-related deaths.
As we reported Wednesday, there's concern about the fire's lingering effects. Erosion from scorched hillsides could pollute the pristine waters of the Hetch Hetchy Reservoir that provides water to about 2.6 million people in the Bay Area. The flames are also threatening the area's ancient sequoias.
Of more immediate concern, KQED adds, is the unhealthy air in areas where the fire's smoke is spreading. A map produced by the federal government's AirNow website shows a large patch of "unhealthy" air in the Thursday forecast for an area that straddles the border of Northern California and Nevada.