Stoked by the arrival of high temperatures and extremely dry air after weeks of unusually mild summer weather, the 2.6-square mile Morris Fire in Angeles National Forest produced a pungent white haze that spread through the Los Angeles Basin and east into San Bernardino County.
Late in the day Wednesday, a new fire erupted several miles to the west above the city of La Canada Flintridge, but it also was burning upslope and away from homes. At least 20 acres had burned by evening with 20 percent containment, U.S. Forest Service spokesman Bruce Quintelier said.
"It's pretty bad, the smoke," said Natacha Cuvelier, a 20-year-old student at the University of Southern California in Los Angeles. "Once I stepped out of the door, I could smell it."
The air was considered unhealthy in many areas, and regional officials urged people to avoid strenuous activities, indoor and out.
Schools were advised to suspend physical education and sports, said Dr. Jonathan Fielding, Los Angeles County's director of public health.