SAN FRANCISCO — Smoke from the wildfires north of San Francisco plunged air quality levels in the Bay Area to the same unhealthy level as China's notoriously polluted capital, sending people to emergency rooms and forcing schools to close and people to wear masks when they step outside.
The region has endured days of choking smoke since the fires began Sunday night and claimed at least 31 lives and destroyed thousands of homes and businesses.
Air quality in most of the region Thursday and Friday was as bad as smog-choked Beijing, according to the Bay Area Air Quality Management District.
"We have unprecedented levels of smoke and particles in the air that we normally don't see," said Ralph Borrmann, a spokesman for the district.
He called it the worst air quality ever recorded in many parts of the Bay Area.
Officials warned that very fine smoke particles, thinner than a human hair, can get lodged in the lungs and into the bloodstream, causing irreparable damage to the body. In Solano County, hospitals there received more than 250 people who complained of toxic air inhalation, county health officer Bela Matyas said Thursday.
At an Ace Hardware store in San Francisco's financial district, phones were ringing nonstop with customers looking to buy breathing masks, but they were sold out, as were most stores in the area.
With winds expected to keep blowing in smoke from the fires to populated areas this weekend, many schools decided to close Friday and organizers canceled weekend events, including an Oktoberfest in Walnut Creek and a fitness festival and half marathon in San Francisco.
Sports teams are monitoring the air quality as they prepare to host games. Some members of the Oakland Raiders wore masks during workouts Thursday.
The NFL has been exploring options to move Sunday's game between the Oakland Raiders and Los Angeles Chargers if it becomes necessary.
Oakland, some 45 miles (72 kilometers) south of the fires, has been blanketed by smoke.
Officials at the University of California, Berkeley and Stanford are monitoring the air quality as weekend football games approach.