OSHA, the Occupational Safety and Health Administration, is the US federal agency that sets and enforces workplace safety and health rules. Employers have a general duty to provide a workplace free from recognised hazards, plus specific standards from egress to ergonomics guidance.
For office employers the recurring OSHA-relevant items are emergency egress and evacuation planning, and knowing who is in the building sits underneath both. The UK equivalent regime runs through HSE, Australia and New Zealand through WHS law.