SARA Title 3 requires employers notify employees of known hazards, and provide for protections from known hazards. The law requires employers inform the employee, plus provide for PPE and training on the required PPE. This is a federal law, and state law only supersedes this law when it’s requirements exceed that of the federal law. State and federal OSHA are the enforcers of said respiratory protection and hazard notification requirement. Any business operating should have employees informed on the hazards, provided masks, and require there use during the course of work. This is one area of legally enforced mandate.

And according to tort law, if a business has a known hazard, it has a duty to inform customers and contractors of the hazard, plus provide mitigation to the hazard. It is in a businesses best interest to require masks in this instance.