Hundreds of thousands of Americans are returning to work but without the federal Covid-19 workplace safety rules the Biden administration wanted released by mid-March.

The Occupational Safety and Health Administration has yet to act on an emergency temporary standard that President Biden directed the agency to consider by March 15.

The directive, issued as one of Mr. Biden’s first actions after taking office, could require employers to develop mandates on masks, physical distancing and air ventilation. The Centers for Disease Control and Prevention currently provides guidelines on these measures, but they aren’t mandatory.

Labor Secretary Marty Walsh “reviewed the materials, and determined that they should be updated to reflect the latest scientific analysis of the state of the disease,” a Labor Department spokeswoman said. “He has ordered a rapid update based on CDC analysis and the latest information regarding the state of vaccinations and the variants. He believes this is the best way to proceed.”

Workplace-safety advocates want the Labor Department to move faster to put rules in place. They argue the coronavirus and highly transmissible strains continue to spread despite vaccination efforts, posing risks to many workers.