After more than a year and a half of low pandemic ridership, the MBTA is expanding some service and taking other steps to welcome commuters back. But they want to make sure those riders wear a mask.

Last week, the Transportation Security Administration extended its mask requirement for planes, buses, trains and other public transportation until January of 2022.

"That means that everybody, everybody has to wear a mask on the MBTA," Ken Green, the MBTA Transit Police Chief said at a press conference Thursday at the Back Bay station. "We've seen a high level of compliance across the system."

But, he said, things could be going better. "There's a growing concern that our employees who interact with the public about not wearing a mask are being verbally, and sometimes, in some cases, physically assaulted, simply just for asking somebody to wear a mask."

Green said over the last year there have been 18 assaults against MBTA workers who asked a rider to wear a mask.

"We recently witnessed one of our riders kick out one of our windows and verbally threaten the operator because she did not want to wear a mask," he said. "This behavior is unacceptable and won't be tolerated."

In terms of ridership, MBTA General Manager Steve Poftak said they're expecting to see "an incremental increase with probably an inflection point in early September," although he acknowledged a lot could change.

"When people are ready to travel, when they need to travel, the MBTA is ready and it's safe," Poftak said.

In an effort to get more people to start riding the T again, officials announced that they're extending the pilot of the so-called "Flex Pass," which is good for any five days of travel within a 30-day period. That test prgram was scheduled to expire Septemebr 15, but will now extend through March 15. And Poftak said a new schedule starting this Sunday will include some increases in service.

Poftak said commuter rail ridership continues to be far below it was before the pandemic. Between 30,000 and 32,000 people are riding the commuter rail each day, he said.

"We believe that we have the right amount of service out there right now. We're only at about 25 to 30 percent of pre-COVID capacity," he said. "That's something that we will track very carefully. If we need to adjust the schedule, we will."