As public and occupational health agencies around the word continuously reevaluate their responses to the spread of monkeypox (also called MPX), California has issued the first regulation-oriented guidance I’ve seen. On September 13, the Division of Occupational Safety and Health (DOSH, but universally called Cal/OSHA) issued “Protecting Workers from Monkeypox (MPX) for Employers and workers Covered by the Aerosol Transmissible Diseases Standard (Title 8 section 5199).” Depending whether MPX comes to be considered an epidemic, this Cal/OSHA effort may be the first of many – I’ve written about public health and OSH agency responses to the COVID-19 epidemic many times since 2020 – or an outlier reflecting California’s aggressive approach to potential hazards. The remainder of this note discusses the new guidance, which is targeted at health and public service workplaces but has relevance for other employers as well.