The Environmental Protection Agency defended its controversial decision to halt enforcement of bedrock anti-pollution laws amid the coronavirus pandemic on the grounds that doing so protected workers and offered flexibility to companies facing staffing shortages.

Yet now the union representing the agencys own workers say the Trump administration is putting them at risk by rushing to reopen federal offices, even as the White House looks to codify the leniency it gave polluters.

In a letter sent to Massachusetts Sens. Elizabeth Warren and Ed Markey, the EPA said its order in late March to temporarily stop policing pollution appropriately balances the need to keep essential services running with steps necessary to contain the spread of COVID-19.

EPA is mindful of the health and safety of the public, as well as workers, EPA staff, and co-regulators, Joseph Brazauskas Jr., an associate administrator at the agency, wrote in the May 8 letter, responding to the senators inquiry from a month earlier. EPA is taking these important considerations into account as we all continue our work to protect human health and the environment.

The letter, which HuffPost obtained , listed steps the agency took to encourage employees to work remotely, and said it was evaluating options to provide as much flexibility to our employees as possible so that they can balance work and family responsibilities.