Audit, Compliance and Risk Blog

OSHA begins nationwide effort to prevent work-related heat illness

Posted by Jon Elliott on Wed, Oct 13, 2021


In September 2021, the US federal Occupational Safety and Health Administration (OSHA) announced its first steps toward nationwide enhancement of efforts to protect workers from heat illness. The effort will cover both outdoor work in the sun and ambient heat, and indoor work in hot areas or heat-retaining clothing and equipment. OSHA’s first step was to release new “Inspection Guidance for Heat-Related Hazards” on September 1. The remainder of this note discusses this policy, and identifies additional context that clarifies ambiguous points.

How Can Heat Cause Illness?

In a hot working environment, a worker’s body must shed excess heat to maintain a stable internal temperature. This is accomplished mainly by circulating blood to the skin, and by sweating and thermal radiation. They become less effective when the air temperature is close to or warmer than body temperature, and/or when high humidity thwarts effective evaporation. Even when these work, the worker’s body tends to heat up, and fluids and salts lost in sweat will have to be replaced.

OSHA’s new Inspection Guidance refers to the National Weather Service (NWS) “heat index” (HI), which factors temperature and relative humidity to classify environmental heat into four categories:

  • Caution (80°F - 90°F HI)

  • Extreme Caution (91°F - 103°F HI)

  • Danger (103°F - 124°F HI), and

  • Extreme Danger (126°F or higher HI)

Furthermore, worker exposures and heat stress are affected by how strenuous their activities are, and how confining and heat-retaining their clothing and gear. OSHA’s new Inspection Guidance refers to recommendations in the National Institute for Occupational Safety and Health (NIOSH) “Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments.”

Injury and illness caused by occupational heat exposures are subject to OSHA authority. OSHA’s new Inspection Guidelines refer to these issues, but do not provide working definitions. The NIOSH Criteria discuss heat stress, illness and injury and provide references and guidance, but do not adopt any specific criteria. In my recent discussion (you can find it HERE), I referenced California’s definition of “heat illness: "a serious medical condition resulting from the body's inability to cope with a particular heat load, and includes heat cramps, heat exhaustion, heat syncope and heat stroke."

What approaches does OSHA’s new Inspection Guidance take?

OSHA applies the new Inspection Guidance to indoor and outdoor worksites where potential heat-related hazards exist.  It notes that serious heat-related illnesses occur in all major industry sectors of employers, including general industry, construction, agriculture, and maritime.  Furthermore, typical worksites where heat-related illnesses may occur include:

  • Indoors – foundries, brick-firing and ceramic plants, glass production facilities, rubber products factories, electrical utilities (particularly boiler rooms), bakeries, confectioneries, commercial kitchens, laundries, food canneries, warehouses without adequate climate control, chemical plants, and smelters

  • Outdoors – agriculture, landscaping, construction operations, refining gas/oil and well operations, asbestos and lead removal, waste collection activities, package and mail delivery, and any other activities that require moderate to high physical exertions or the wearing of heavy or bulky clothing or equipment on a hot day.

The Inspection Guidance applies to “heat priority days,” which it defines as days with a heat index that exceeds 80°F. OSHA Area Offices are to assess the potential for heat-related illnesses and deaths at both indoor and outdoor worksites where heat-related hazards may exist on heat priority days. OSHA site inspections during such days are to address heat hazards; OSHA also states that regional and state offices can establish “emphasis programs” to target additional inspection and enforcement during such days (noting that OSHA Region VI (Texas and adjoining states) and several states have done so).

The Inspection Guidance directs inspectors to do the following during heat-related inspections:

  • “Review OSHA 300 Logs for any entries indicating heat-related illness(es),

  • Review injury and illness reports and obtain any records of emergency room visits and/or ambulance transport, even if hospitalizations did not occur,

  • Interview workers for reports of headache, dizziness, fainting, dehydration, or other symptoms that may indicate heat-related illnesses,

  • Review employer’s plan to address heat exposure, including acclimatization procedures (especially for new and returning workers), work-rest schedules, access to shade and water (with electrolytes when needed), and any training records associated with implementing a heat illness prevention program,

  • Document, where possible, the heat index on the OSHA-NIOSH Heat App, using the screen save feature on a mobile phone or tablet,

  • Identify conditions and activities relevant to heat-related hazards. These can include, but are not limited to:

  • Potential sources of heat-related illnesses (e.g., working in direct sunlight, a hot vehicle, or areas with hot air, near a gas engine, furnace, boiler or steam lines),

  • Wet bulb globe temperature calculations and/or other temperature measurements,

  • Heat advisories, warnings or alerts,

  • The use of heavy or bulky clothing or equipment,

  • The types of activities performed by the employees and whether those activities can be categorized as moderate, heavy or very heavy work,

  • The length of time in which a worker is continuously or repeatedly performing moderate to strenuous activities,

  • Heat-related illnesses among new workers,

  • The presence of any recent vacation time or breaks in employment prior to complaints of heat-related symptoms, and

  • The availability of rest breaks, water and shade on site.”

The Inspection Guidance also includes additional procedural details for heat-related inspections, citations, and enforcement. It also provides links to additional information on OSHA and other agency websites.

Now what?

OSHA has declared it will apply these new Inspection Guidelines. The agency has also stated that it will begin to develop a national heat illness regulatory standard, beginning in October 2021 with an Advance Notice of Proposed Rulemaking on heat injury and illness prevention in outdoor and indoor work settings. By the summer of 2022 these activities should be well advanced, so employers not already subject to state-level requirements should be sure to evaluate applicable heat hazards and their protective measures.

Self-Assessment Checklist

Do any of my organization's workers work in situations where ambient heat may create a hazard of heat illness:

  • Outdoors (e.g., agricultural or construction work)?

  • Indoors (e.g., work in manufacturing or other processes involving hot materials or equipment)?

If so, does the organization provide appropriate:

  • Training (tailored to the workplace source(s) of heat hazards, preventive measures, and responses to heat illness?

  • Water?

  • Shade or other appropriate ways for workers to cool down?

  • Planning and procedures?

Where Can I Go For More Information?

  • OSHA

 - “Inspection Guidance for Heat-Related Hazards” (9/1/21)

 - “Heat” webpage

- Cal/OSHA “Heat Illness Prevention webpage

- California Occupational Safety and Health Standards Board “Heat Illness Prevention in Indoor Places of Employment” working group webpage

- Canadian Centre for Occupational Health and Safety “Hot Environments - Health Effects and First Aid” webpage 


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About the Author

Jon Elliott is President of Touchstone Environmental and has been a major contributor to STP’s product range for over 30 years. 

Mr. Elliott has a diverse educational background. In addition to his Juris Doctor (University of California, Boalt Hall School of Law, 1981), he holds a Master of Public Policy (Goldman School of Public Policy [GSPP], UC Berkeley, 1980), and a Bachelor of Science in Mechanical Engineering (Princeton University, 1977).

Mr. Elliott is active in professional and community organizations. In addition, he is a past chairman of the Board of Directors of the GSPP Alumni Association, and past member of the Executive Committee of the State Bar of California's Environmental Law Section (including past chair of its Legislative Committee).

You may contact Mr. Elliott directly at:

Tags: OSHA, Heat Wave, Heat