The U.S. Environmental Protection Agency has announced that it has started the process of reopening its Philadelphia office, a regional headquarters for five states and Washington, D.C., prompting the agency’s largest union to question whether it is safe to return amid the coronavirus pandemic.

The Region 3 headquarters at 17th and Arch Streets has more than 700 workers to serve Delaware, Maryland, Pennsylvania, Virginia, and West Virginia as well as Washington.

“The rush to reopen Region 3 offices makes no sense,” said Marie Owens Powell, president of American Federation of Government Employees Local 3631, which represents 659 employees at the Philadelphia offices. “EPA employees for months have been effectively working from home, carrying out the EPA’s mission to protect human health and the environment. There is no reason why telework cannot continue until either a vaccine or effective treatment are available.”

Powell said the EPA has not offered a reason for reopening that “justifies the risk to employee health and welfare.”

She said the EPA has been “stonewalling” union requests to see the data it is using to determine which offices should reopen.

Last week, EPA Administrator Andrew R. Wheeler said the agency’s “research scientists” created reopening criteria using data from Johns Hopkins University and the U.S. Department of Health and Human Services. Wheeler said he is briefed on the status of each facility every day. The EPA is using a dashboard of metrics. Once a facility is designated as “green,” it can be reopened.

The Philadelphia facility has been designated as green and will be disinfected this week as employees continue to work from home. In Phase Two, employees are expected to return to work but can be exempted with a manager’s permission. In Phase Three, all employees must return unless they are sick or meet other exempting factors.

It takes several weeks to complete the reopening phases, which can be rolled back if needed.

“This is a very methodical approach,” Wheeler said. “It’s going to be a very slow process. The data for Philadelphia is looking pretty good at this point.”

However, in a letter to Region 3 Administrator Cosmo Servidio, Local 3631 said scientists within the union analyzed the EPA’s reopening metrics and dispute the findings. For example, the union said the EPA is relying on state data for a trend in influenza-like illnesses rather than Philadelphia’s own data, which find community transmission is still occurring.