Some people wore masks as they walked or rode their bikes to work—an uncommon sight in the Bay Area.
"These fires are bringing Beijing to the Bay Area and are allowing us to see what they experience around the clock," says Richard Muller, a UC Berkeley professor of physics who co-founded the site Berkeley Earth, which tracks air quality around the globe with an interactive map.
On the morning of Oct. 12, the amount of particulate matter in the area in some parts of San Francisco were in the 151-200 range on the air quality index, matching that in Beijing.
"We're seeing the worst air quality ever recorded in many parts of the Bay Area," Flannigan told SFGATE earlier this week. "The entire Bay Area population is likely being affected by the smoke."
Brian Garcia, also a meteorologist with NWS, agreed.
"We're going to see a really strong settling of the smoke in the Bay Area on Friday and Saturday," he said. "Not to mince words. It's going to be really bad. It's not going to be fun."