Heat Safety Regulations
Consider this scenario: two crews framing roofs in two new subdivisions in July. One crew is working in Lubbock, Texas, while the other works outside Salem, Oregon. By late morning, temperatures at both sites are soaring, with the heat index approaching 96oF. Working in such conditions, heat management becomes a very real concern.
To handle the heat, the crews (like all humans) are equipped with the same physiology: somewhere between two and four million sweat glands, a cardiovascular system that circulates blood to shuttle heat away from organs and working muscles towards the skin, and a tolerance for an internal temperature that tops out around 104oF before heat stroke becomes a real, potentially fatal, problem.
All humans have these same biological mechanisms, so the biggest variable in how the crews experience heat stress isn’t their physiology.[1] Instead, it may come from their legal protections. By state law, the Oregon crew’s employer must provide 32 ounces of drinking water per person each hour, a written rest break schedule and shaded area for workers to cool off, and a formalized acclimatization plan for anyone new on the job. The Texas crew is covered only by the employer’s judgement.
This article isn’t a value judgement on merits of local vs. state vs. federal worker safety and oversight. Instead, we’ll objectively explore the patchwork of rules and regulations around heat stress across the U.S., identifying best practices that can be applied at the job site regardless of state line or formal regulation. We’ll contrast these with heat safety regulations from a few other countries as well. After all, heat stress doesn’t care what city, state, or country you’re working in.
Heat Safety Physiology
There is a fundamental truth to working in hot temperatures: no one can outwork heat. Try to keep pushing through and even the toughest, fittest, most acclimatized among us must slow down, stop, or fall victim to the heat.
It’s a truth based on human physiology and physics. Work requiring muscle power and physical movement usually generates several times more metabolic heat than sitting at rest. The harder the effort, the more metabolic heat generated. For an extreme example, a Tour de France elite cyclist may sustain a heat production of 1,400 Watts, more than ten times the amount produced when that cyclist is resting. This metabolic heat must be dissipated to prevent a dangerous rise in body core temperature. The hotter and more humid the environment, the more difficult it is to dissipate metabolic heat.
In hot conditions, we have few choices: balance the amount of metabolic heat we generate with the amount we dissipate by reducing our working effort (something not always possible in environments of extreme heat and humidity); stop working completely and cool off, allowing the body to dissipate excess heat before resuming the effort; or allow our body temperature to climb to levels where heat stroke becomes likely.
Most of us instinctively slow down or stop working when our body core temperature gets too high. This innate response keeps us from dangerous overheating, but at the cost of reducing output. Studies using multiple labor productivity models estimate extreme temperatures eroded an average of $220 billion from U.S. economic productivity in 2023.
Sometimes, because of motivation to get the job done or a need to keep working to pay the bills (frequently likely when workers are paid piecewise by output or amount produced), workers continue pushing beyond the point they should have stopped. The Department of Labor records 479 worker fatalities between 2011 and 2022, but this is almost certainly a vast undercount. The same study notes heat-related worker deaths may be undercounted by a massive factor of 14, meaning the true number of fatalities over that period may exceed 6,700 workers!
No Federal Heat Stress Regulation
At the federal level, no direct heat stress regulation acknowledges the danger of heat stress in the workplace. This isn’t to say employers can disregard extreme temperatures entirely. Workers at hot job sites are protected, if indirectly, by Section 5(a)(1) of the Occupational Safety and Health Act. Known as the “General Duty Clause”, this statute simply (if somewhat vaguely) says employers must provide a workplace free from hazards likely to cause death or serious injury.
And working in hot conditions can be hazardous, especially when the work involves manual labor. From April 2022 through December 2024, OSHA conducted roughly 7,000 heat related inspections and issued 60 citations (along with 1,392 hazard alert letters) for failure to follow the General Duty Clause. Across 2022 and 2025, approximately 50 of those inspections each year resulted from a heat-related worker fatality. Since April 10th of 2026, the directive driving these inspections has been refined to focus on heat in 55 high-risk industries, including many agricultural, manufacturing, and transportation sectors.
There is actually a current effort to create a federal heat safety standard. In 2024, OSHA published a notice of proposed rulemaking for a heat-related worker safety standard. The standard, which would apply to employers in general industry, construction, maritime, and agriculture sectors, would require employers to create plans to evaluate and control heat hazards in their workplace, clarifying obligations and steps required to protect employees from hazardous heat. Among other requirements, it includes mandated paid rest breaks and (if it is provided, which is not mandated) a requirement to ensure cooling personal protective equipment (PPE) is maintained when working in hot conditions.
However, it's unlikely this proposed federal rule will take effect anytime soon. OSHA completed nearly all procedural steps to implement the rule last October. The deadline to issue, modify, or decline the rule then passed in December without action. Instead of a final rule, the Department of Labor intends to revisit the effort with a supplemental Notice of Proposed Rulemaking in December 2026, reopening the heat safety standard for additional modification and restarting the public comment, hearings, and drafting steps. Even if this supplemental proposal moves ahead on schedule, given historical timelines to implement new OSHA standards, a nationwide heat standard is unlikely before 2028.
State-level Requirements
In the absence of federal regulations, states have gone in several directions. Most have no specific regulations regarding heat and worker safety, but seven states (California, Washington, Oregon, Nevada, Colorado, Maryland, and Minnesota) implemented their own heat safety standards. However, standards across these states vary widely.
Perhaps unsurprising given its reputation for regulation, California adopted the first outdoor heat safety standard in the country. Now covering both indoor and outdoor workers, the standard includes additional high heat procedures for agriculture, construction, landscaping, oil and gas extraction, and the transportation and delivery of heavy materials. At any temperature or job site, employers must supply one quart of water per worker per hour, maintain a written heat illness prevention plan, train workers and supervisors, and allow cool-down rests on request. Once the temperature exceeds 80°F, shade must be present on site.
Above 95°F, employers in the five industries covered by high heat policies must actively observe workers for symptoms of heat illness, remind them to drink water, and hold pre-shift meetings. Additionally, agricultural employers must be provided a 10-minute cool-down period every two hours. New workers at high-heat job sites specifically listed for close observation during their first 14 days, roughly the period over which heat acclimatization develops. Indoor regulations, covering nearly all indoor worksites, are similarly structured above 82°F.
Washington, Maryland, and Oregon standards follow California’s closely, setting an initial temperature trigger at 80oF with enhanced protocols during higher temperatures (the threshold for enhanced rules varies across state). Oregon and Maryland standards also apply to both indoor and outdoor workers.
While Washington’s standards apply only to outdoor workers, they are unique among state standards in that regulations begin at a thermal trigger of 52oF for workers wearing non-breathable clothing. As we’ve discussed in our PPE and Heat Stress article, vapor-barrier clothing (such as chemical splash or HAZMAT suits worn in hazardous environments) severely restrict a person’s ability to thermoregulate. This rule explicitly acknowledges the large burden PPE places on worker thermoregulation in some (admittedly niche) occupational settings.
The remaining three states with heat safety regulations take different approaches. Colorado’s “Rule 3” of its agricultural labor rules defines heat safety requirements only for agricultural workers, largely following temperature thresholds and worksite requirements also implemented in California, Oregon, and Washington. For non-agricultural workers exposed to heat, Colorado recently passed legislation requiring data gathering and the development of a state heat injury and heat illness prevention plan. Resulting rules or regulation (should any be implemented) are not expected until 2028. Virginia, which lacks current heat safety regulation, has a similar approach, with a standard under development and set to implement in May of 2028.
Minnesota, known more for cold winters than hot summers, has heat safety standards applicable only to indoor workers. Despite applying only indoors, Minnesota standards are unique in being based around metabolic heat production, treating heat exposure in a manner somewhat similar to chemical exposure. Instead of a simple temperature threshold triggering workplace safety action, Minnesota regulation uses the Wet Bulb Globe Temperature (WBGT) thermal index (more accurately, the indoor variation of true WBGT) and scales when regulations kick in based on workload.
According to Minnesota rules, workers “shall not be exposed to indoor environmental heat conditions in excess of” a two-hour time-weighted average of a WBGT limit that is based on the work being performed. “Light” work (sitting, standing) can be performed in WBGT conditions up to 86oF, “moderate” work (some walking and lifting) up to 80oF, and “heavy” work (shoveling, lifting heavy boxes) is restricted to environments with a (two-hour time weighted average) WBGT index no greater than 77oF. These thresholds are reminiscent of the work-rest guidelines the U.S. military uses to mitigate heat stress. These tiered thresholds recognizes that metabolic heat production, and therefore the need to shed heat, is greater during physically demanding work.
Finally, we have Nevada. Standards in Nevada don’t set any thermal limit or threshold for workplace safety actions. They require a one-time written job hazard analysis, one-time employee training, identification of a person responsible to monitor conditions and summon medical care when needed, and a written safety program. Rest breaks are required only when employees exhibit heat illness symptoms. Nevada OSHA's implementing guidance does, however, specifically identify cooling vests (such as the Qore Performance ICEPLATE® system) as an acceptable form of thermal control when other controls are insufficient.
States Without Requirements
While most other states have no explicit heat safety regulation, two States moved regulation in the opposite direction. Texas and Florida both passed legislation directly banning the creation of local heat safety standards without creating state-level requirements.
On the surface, Texas' law, the Regulatory Consistency Act, doesn't have anything to do with heat safety. Instead, it aims to "provide statewide consistency" by eliminating what the Texas legislature called a "patchwork of regulations" at local levels. A Texas city or county may not adopt or enforce an ordinance "unless expressly authorized by another statute." Because Texas has no state heat safety standard and hasn’t authorized local ones, the practical effect is that (aside from the federal General Duty Clause) no level of government in Texas requires an employer to comply with heat safety standards. Prior to the law passing, both Austin (in 2010) and Dallas (in 2015) had city ordinances mandating a ten-minute rest and water break every four hours for construction workers; both were rendered void by the Regulatory Consistency Act.
Florida is more direct in preventing the creation of local heat safety standards. Florida's 2024 House Bill 433 states a political subdivision (i.e., local governments like cities or counties) "may not establish, mandate, or otherwise require an employer... to meet or provide heat exposure requirements not otherwise required under state or federal law." This includes (among other things) monitoring, water access, rest breaks, cooling measures, and acclimatization periods. Because Florida has no state-level heat safety standard, the practical effect is that no local government in Florida can require anything more stringent than the federal OSHA General Duty Clause.
Other Countries
Some of the world’s most restrictive heat safety regulations are found in the Middle East. Gulf states regulate workplace heat safety by restricting outdoor work during the hottest periods of the day during the hottest months of the year. For example, the UAE outright bans outdoor work from 12:30 to 3:00pm between June 15th and September 15th; Saudi Arabia from 12:00 to 3:00pm; and Kuwait from 11:00am to 4:00pm, June through August. Qatar implements the strictest rules. In addition to mandatory employer risk assessments and annual worker health exams, outdoor work is prohibited from 10:00am to 3:30pm between June 1st and September 15th and all work must stop whenever a worksite WBGT exceeds 32.1oC (about 90oF). Qatar’s Ministerial Decision No. 17 is a heat regulation with a published evidence base, built on physiological and workload data across more than 5,500 worker-hours during the summer of 2019. All these regulations far exceed anything implemented in the U.S.
Australia is a counterpoint example to the Gulf states, with national level regulation more similar to the U.S. “General Duty Clause”. There is no maximum work temperature triggering protective actions. Australian employers must eliminate or minimize heat risk “so far as is reasonably practicable,” and Safe Work Australia explicitly does not publish a stop-work temperature on the grounds that no single number can account for the interplay of factors contributing to heat stress, including humidity, air flow, work intensity, duration, and clothing or PPE found across diverse worksites.
Qore Performance – Action With or Without Guidance
For American workers, heat regulations vary by state, but the physiological effects of worker heat stress don’t care about jurisdiction. Workers’ compensation claims, lost productivity, and General Duty Clause liability all remain despite the presence or absence of formal heat safety standards.
Regardless of local regulations, in environments where heat stress exists, Qore Performance products are an important tool. If local regulation mandates controls, ICEFLASK® and ICEPLATE® can help satisfy mandatory hydration requirements while boosting the efficacy of mandatory cooling breaks through conductive cooling. Absent workplace heat stress regulation, those products are tools in addressing the General Duty Clause requirement to provide a workplace free of environmental hazards.
In any hot environment, Qore Performance helps keep workers more productive for longer. Qore Performance’s ICEPLATE®-based cooling and hydration acts directly on the body’s heat balance, drawing stored heat by conduction when evaporation is blocked, and can assist when worn under worksite required PPE. Regardless of regulations, it’s ultimately the worker’s core temperature that matters, a challenge employers can address today.
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About the author: Dr. Erik Patton holds a PhD from Duke University where he conducted research on the challenges rising temperatures pose for military training. An Army veteran, Erik has served in a variety of extreme climates ranging from deserts in the U.S. Southwest and Middle East (120oF) to Arctic conditions in central Alaska (-42oF).
[1] We’re assuming everyone on the crew is relatively young and healthy, and no one is taking medication that makes them more susceptible to heat stress.
