I did some more research and it seems like we’re both right. Yes, the US OSHA (the Australian body has the same name) does not actually have a national standard

I did some more research and it seems like we’re both right. Yes, the US OSHA (the Australian body has the same name) does not actually have a national standard for heat-related illnesses. It does however have plenty of (non-Californian) material specifically on heat-related illnesses, e.g. https://www.osha.gov/otm/section-3-health-hazards/chapter-4 https://www.osha.gov/otm/section-3-health-hazards/chapter-4. According to https://www.shrm.org/resourcesandtools/legal-and-compliance/employment-law/pages/osha-announces-program-to-protect-workers-from-heat-hazards.aspx https://www.shrm.org/resourcesandtools/legal-and-compliance/... (archive here https://archive.md/rHMQm https://archive.md/rHMQm) this is enforced under the general duty clause: > Federal OSHA enforces heat-related safety under the Occupational Safety and Health Act's general duty clause, which requires employers to provide workplaces that are "free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees." https://www.fisherphillips.com/news-insights/osha-unveils-program-extreme-heat-workplace.html https://www.fisherphillips.com/news-insights/osha-unveils-pr... agrees: > There is no heat-related or heat stress standard in place. Instead, federal OSHA has traditionally enforced heat-related hazards through its General Duty Clause. I will happily admit I was surprised to learn that US federal OSHA does not have specific heat-related illness regulations and have been instead making do with Commerce Clause-style general regulation to enforce heat safety instead. But I was also correct when I said there is plenty of US federal (not state-specific) OSHA material on heat-related illnesses - that osha link above has a detailed breakdown including worked examples on how to use Wet Bulb Globe Temperature testing equipment to measure heat stress risks, tables of Threshold Limit Values, etc. I also found a convincing explanation for my confusion as to why the former head of OSHA would say that OSHA does not have a national standard for heat-related illnesses when they empirically do have lots of specific material on assessing and managing heat risk: US federal OSHA is (as of October 2021) working on instituting a comprehensive national heat standard https://www.regulations.gov/document/OSHA-2021-0009-0001 https://www.regulations.gov/document/OSHA-2021-0009-0001 and that seems to be why the lack of a national standard was emphasized - it is no doubt a mammoth and expensive task, and it is the natural order of bureaucracy that any such task must be continually justified to protect from bean counter cuts.