Mount Sinai officials said there would be 70 beds in the new building, down from 825 beds (of which only half are in use). But Ms. Mendez learned, and the hospital confirmed on Thursday, that 153 existing beds for mental health patients would remain in the new hospital.

“As long as they can show me that the services that are needed will still be there, and even if it may look a little different, then I will get more comfortable,” Ms. Mendez said.

But as throngs of employees arrived for meetings in the stifling sun on Thursday, there was an air of unease. They said they were told by hospital officials not to speak publicly about the situation.

One man, an electrician who asked not to be identified by name for fear of endangering his employment, said that during Hurricane Sandy, he spent his 60th birthday at Beth Israel and did not leave for five days after that. With much of Lower Manhattan flooded, he was making sure the generators were operating.

He is a native of Panama, he said, and he had been at St. Vincent’s Hospital Manhattan for 20 years when it was shut down to make way for condominiums. He started working at Beth Israel five years ago.

“You get that sense of helping the less fortunate,” he said, but added, “There’s no more charity; it’s more about the dollar.”

According to Times archives, when Beth Israel was founded, other hospitals would not accept immigrants who had been in the city for less than a year. Beth Israel took every immigrant.