Air quality remained poor in the central San Bernardino Mountains and parts of the San Bernardino Valley, as well as swaths of Orange and Riverside Counties. In San Diego County, where only two of five major fires was more than 50 percent contained, the air was especially dismal Friday.

That worried Joe Flynn, 48, as he prepared to return home to Ramona, northeast of San Diego, after he and thousands of other evacuees sought shelter Qualcomm Stadium this week.

But the pull to get back to normal was even stronger.

"Sure I'm worried about breathing that stuff up there," he said. "It's not cool but everyone is dying to get back home."

Satellite pictures showed thick smoke continuing to hang over the entire region, affecting schools, events and the health of residents all over Southern California.

Residents staying in areas with bad air were advised to avoid exerting themselves. Children and people with heart and respiratory conditions were urged to stay indoors with the windows and doors closed and the air conditioner on.

"In the immediate aftermath of a fire, we're all at risk of the fine particulate matter we can inhale," said Julia Robinson Shimizu, a spokeswoman for Breathe L.A. "In general it's good to limit outdoor strenuous activity at least seven days after the fires have ended."

The University of California San Diego Medical Center saw an increase in patients coming in with breathing troubles they believe were related to air pollution, spokeswoman Jackie Carr said.

Mayor Jerry Sanders said the NFL's San Diego Chargers would play Sunday's game scheduled at Qualcomm. The stadium can seat more than 70,000 people.

But Ross Porter, a spokesman for the American Lung Association of California, urged fans to use caution when deciding whether to attend.

"Sometimes its better to sit quietly at home and watch it on TV," he said.

Meanwhile, about 23,000 homes were still threatened by five major blazes in three counties. Altogether, more than a dozen fires raced across more than 503,000 acres - the equivalent of 786 square miles - although many of the blazes have been contained.

At least three people - and possibly as many as seven - have been killed by flames. About 1,700 homes have been destroyed and damage estimates have surpassed $1 billion.