Several San Francisco Bay Area counties are joining San Francisco in banning all indoor dining and scaling back other activities as coronavirus cases surge nationwide, alarming public health officials as the holidays approach.

Santa Clara, Marin and Contra Costa counties announced Friday that they will halt indoor dining as of Tuesday.

Contra Costa County also is ordering indoor gyms and fitness centers to close. Santa Clara is requiring gyms to operate at 10% capacity and closing all outdoor bars, bowling alleys and other indoor family centers.

The Bay Area generally has been more cautious than the rest of the state in allowing activities during the pandemic, and health officers representing 7 million people implemented a stay-at-home order back in March ahead of a similar order by the state.

Dr. Sara Cody, health officer for Santa Clara County, which is home to Silicon Valley, said it is “absolutely imperative” to take action given the steep increase in cases starting around Election Day. She said she expects the state to move the county back to a more restrictive tier of operation and would rather not wait to take action.

“We do not take these actions lightly, not at all,” she said. “These are extraordinarily difficult decisions to make.”

San Francisco’s ban on indoor dining goes into effect Friday night, and Marin County, which had just this week recommended restaurants voluntarily reduce capacity indoors to 25%, said Friday that it would not permit any inside dining.

Businesses have pushed back on the idea that restaurants and gyms are to blame for virus transmission, and health officials have said that small, casual gatherings at home where family and friends are not wearing masks or socially distancing are to blame for the latest surge.

But Cody said eating indoors where masks cannot stay on at all times “is a very high-risk activity.”

Contra Costa County also is requiring concession stands at movie theaters to close starting Tuesday, said Dr. Chris Farnitano, county health officer.

“We chose these activities because of the risks involved,” Farnitano said, about indoor dining, gyms and movie theaters. “Diners at restaurants remove their masks to eat or drink, as do movie patrons when snacking on food from concession stands.”

He said that heavy breathing while exercising can transmit virus particles up to 10 feet (3 meters). The order does not have an end date and will be reevaluated when numbers decrease, he said.