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  • Writer's pictureAdele L. Abrams, Esq., CMSP

Maryland OSHA Proposes Heat Stress Rule

On October 7, 2022, the Maryland Department of Labor proposed adoption of a heat stress standard, to be enforced by the department’s state-plan OSHA agency (MOSH). The proposed rule appears in the Maryland Register, Vol 49, Issue 21, and has a comment deadline of November 7, 2022, although that could be extended. The proposal was initially considered at an open meeting of the Maryland Occupational Safety and Health Advisory Board on August 23, 2022, and would apply to all industry sectors under MOSH jurisdiction.

The standard would be triggered when the “heat index” reaches 88 degrees Fahrenheit, or where external influencing factors increase the potential for serious heat-related illness – including radiant heat sources, conductive heat sources, movement of air, severity and duration of workloads, and the protective clothing and other PPE worn by the worker. The “Heat Index” is not specified but simply is defined as the “apparent temperature … what the temperature feels like to the human body, when relative humidity is combined with the air temperature.”

The rule would also require employers to consider workers’ “Personal risk factors” for heat-related illness when crafting a program and protocols. Those factors include: age, degree of acclimatization, health, consumption of water, alcohol and caffeine, and use of prescription medications. Inquiries into these matters may have implications under the Americans with Disabilities Act and the Age Discrimination in Employment Act, as well as the analogous Maryland and county statutes. Some inquiries could also raise HIPAA issues.

Where conditions trigger the rule, employers would have to have a heat-related illness prevention and management program with provisions for: potable drinking water, rest and recovery breaks with shade or methods of cooling, monitoring of workers for heat-related illness and acclimatization, and identification of work process and external factors that increase the likelihood of heat risk: increased metabolic workloads, radiant and conductive heat sources, increased humidity, decreased air movement, and PPE use.

Both supervisory and hourly workers would also require mandatory training on recognizing working conditions that could cause illness, personal risk factors, importance of frequent consumption of water and acclimatization, and the signs and symptoms of heat illness and response procedures. The proposed rule also has a section on Emergency Response Procedures, making the employer responsible for ensuring effective communications with workers to enable emergency medical services, monitoring workers for signs and symptoms of heat stress, and contacting EMS or transporting workers to emergency medical providers, as needed.

Federal OSHA lost a heat stress case in recent years (Sturgill Roofing), brought under its General Duty Clause, because it attempted to rely on the National Weather Service’s Heat Index, with the court finding that this was not a scientific measurement and therefore could not be used for enforcement. However, that decision is not binding upon Maryland’s agency, which has its own body of case law through the state court system.

Federal OSHA is now in the process of a heat stress standard rulemaking but suggested that an 80-degree actual temperature would be the trigger for provisions. Other state plan states including California, Oregon and Minnesota, currently have heat stress prevention rules but all differ from each other – some only applicable indoors or outdoors. Both the Maryland proposal and the federal rulemaking would be applicable in all work environments, indoors and out.

Comments should be directed to: Michelle F. Vanreusel, Acting Deputy Commissioner, 10946 Golden West Drive, Suite 160, Hunt Valley, MD 21031, or can be emailed to, or faxed to 410-767-2986. No public hearing has been scheduled.

For assistance with comments or heat stress program development, contact Adele Abrams at

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