The Bay Bridge is obscured Thursday as smoke from the Camp Fire fills the air in San Francisco. (Michael Short/Bloomberg)

Several colleges in California’s Bay Area are closed as smoke from the massive Camp Fire has made air quality unhealthful.

The University of California at Berkeley canceled classes and shut down all but essential operations through Friday, Chancellor Carol Christ announced. She reminded students who need respirators that they are available.

The University of San Francisco closed its Northern California campuses through Friday as the air quality index rose above 200 in San Francisco on Thursday. The Environmental Protection Agency rates air quality from zero to 500, with zero being the lowest risk. Air quality measured as 200 to 300 is considered “very unhealthy” and triggers an alert that everyone may experience adverse health effects.

The air quality was another sign of the pervasive impact of the wildfires tearing through California. The fires have destroyed communities, taken more than 60 lives, closed roads, isolated regions and left rescuers searching for hundreds of missing people.

People wear masks Thursday as smoke from the Camp Fire affects the air in San Francisco. (Michael Short/Bloomberg News)

Stanford University and the University of California at Davis also canceled classes Friday.

Wildfires are affecting colleges in Southern California, as well.

Pepperdine University’s Malibu and Calabasas campuses remain closed through the Thanksgiving holiday, and officials plan to reopen Nov. 26. The Woolsey Fire burned on Pepperdine’s Malibu campus earlier this month.

At California Lutheran University, the campus is still sheltering people displaced by the fire and hosting events for local organizations.

The Camp Fire, the deadliest and most destructive wildfire in California history, rampages through the town of Paradise, Calif., earlier this month. (Noah Berger/AP)