Insights from a Construction Safety Week presentation by David Martin (Perry Weather) and Dr. Christy Eason (Korey Stringer Institute)
Heat stress in construction is no longer a summer footnote. It is one of the most measurable, costly, and preventable safety problems on a modern jobsite. At a Construction Safety Week session co-sponsored by Perry Weather, heat safety expert David Martin and Dr. Christy Eason of the Korey Stringer Institute walked through the data, the policy gaps, and the framework that separates construction companies who manage heat well from the ones still reacting after someone gets hurt.
The takeaway for construction leaders is direct. Most companies are tracking heat. Far fewer are acting on what they track. And the gap between awareness and follow-through is where workers get injured, deadlines slip, and liability builds.
How Big Is the Construction Heat Stress Problem?
About 71% of the world’s working population, roughly 2.4 billion people, is exposed to excessive workplace heat. In the United States, more than 13 million workers face extreme heat conditions every summer across construction, agriculture, oil and gas, and other physically demanding industries.
Bureau of Labor Statistics data shows 479 worker deaths attributed to heat between 2011 and 2022, an average of about 40 per year. Then 2023 set a record: 555 heat-related occupational deaths, the highest annual total ever reported. According to OSHA, more than 90% of exertional injuries reported to the agency trace back to heat-related causes.
Construction sits among the two most heat-affected industries globally, second only to agriculture. As David Martin put it during the presentation:
“Extreme heat is just not a seasonal threat, but it’s a daily disruptor within construction sites.”
David Martin, PhD, Perry Weather
Why Construction Workers Face More Heat Risk Than Almost Anyone
Three forces compound on every active jobsite. Each one alone is manageable. Stacked together, they create the conditions for heat illness.
Environmental Heat
Raw ambient temperatures have been climbing over the past two to three decades. High humidity slows the body’s ability to cool itself because sweat cannot evaporate off the skin efficiently. Direct sun makes it worse, and on a construction site the radiant heat coming off steel, asphalt, and concrete adds another layer on top of air temperature alone.
Metabolic Heat
Lifting, climbing, framing, digging, and every other physical task on a jobsite forces muscles to contract and produce heat internally. When the environment is already hot, that internal heat has nowhere to go.
“The muscle activity produces heat faster than the body can shed it when it’s an increased environmental condition.”
PPE and Gear
Hard hats, long sleeves, boots, and impermeable safety equipment are required for good reason. They also trap heat. The same gear that protects workers from one set of hazards adds to another.
“These impermeable PPE, they’re gonna block that sweat evaporation, which is our body’s primary source of cooling.”
The body keeps absorbing more heat than it can release. Core temperature climbs. Heart rate rises. Sweat rate increases. Eventually, when core temperature pushes past roughly 104 to 105 degrees Fahrenheit, the risk of exertional heat stroke becomes severe. Heat stroke is a medical emergency. It can cause central nervous system dysfunction, multi-organ failure, and death.
Every worker on a jobsite should be able to identify the warning signs: dizziness, weak pulse, fainting, extreme fatigue, nausea, very dark urine, and confusion.
The Economic Case for Construction Heat Stress Safety
“Heat is a safety issue. And it’s also a productivity issue.”
Dr. Christy Eason, Korey Stringer Institute
Treating construction heat stress safety as a cost line rather than an overhead inconvenience changes how companies budget for it.
Global labor productivity losses from heat were estimated at $311 billion in 2010. That figure is projected to reach $2.4 to $2.5 trillion by 2030, around 1% of global GDP.
Construction takes a disproportionate share of that hit, with an estimated 19% global productivity loss tied to heat exposure.
Perry Weather’s own survey of approximately 250 U.S. construction companies tells the rest of the story. 79% of construction leaders reported at least one heat-related incident in the past 12 months, averaging 5 to 10 incidents per site per year. 89% observed noticeable productivity drops on hot days, particularly once temperatures crossed 91 degrees Fahrenheit. Sites reported 4 to 6 hours of work stoppages per week, 65% saw daily delays of more than 3 hours, and 59% missed project deadlines because of heat warnings. The average cost per heat incident landed between $5,000 and $10,000.
As Dr. Eason framed it, mistakes increase as workers slow down and fatigue sets in, and that is where injuries happen.
Construction Heat Stress: By The Numbers
The data tells the story of how widespread, costly, and preventable construction heat stress has become.
Sources: Perry Weather survey of approximately 250 U.S. construction companies; Bureau of Labor Statistics; OSHA.
Many Companies Aren’t Properly Enforcing Their Heat Policies
Most construction companies know heat is a problem. The harder question is whether their teams are actually doing anything different on the ground because of it.
Perry Weather’s survey found that 93% of construction companies track heat exposure, use weather forecasts to plan work, and automate alerts when conditions cross critical thresholds like 91 degrees Fahrenheit. But the picture changes fast after that. Only 31% of companies are highly confident in their heat stress policies. Only about half have a formal written policy, and many of those still struggle with compliance. About 13% have no written heat safety policy at all.
Martin was direct about the underlying issue:
“What we don’t see happening is the follow-through.”
David Martin, PhD, Perry Weather
Three patterns explain why good policies often fail before they reach workers.
Three patterns explain why good policies often fail before they reach workers.
Leadership and Coordination Gaps
41% of survey respondents cited coordination issues between crews and managers. 37% pointed to scheduling pressure on deadlines. And 45% rely entirely on supervisors to manage heat risk, which becomes a problem the moment supervisors step off-site.
“Maybe the people on the ground don’t know who should be making these decisions, or they feel like they shouldn’t be making these decisions, so that decisions aren’t made at all.”
Training Gaps
12% of workers have never received formal training to recognize heat stress. Around 35% ignore protocols because they do not connect their symptoms to heat, chalking up early warning signs like fatigue to ordinary tiredness. And 45% of companies only update their heat mitigation practices after a serious incident occurs.
“We don’t see good policies coming into play until someone actually gets hurt.”
Worker Culture Pressures
Deadline pressure, the assumption that someone else is monitoring conditions, and an unwillingness to look weak in front of coworkers or supervisors all push workers to keep going when they should stop. Martin sees the same dynamic in athletic populations.
“People want to make sure that they look good to their employees and bosses, and don’t want to seem like they’re weaker, maybe in fear of getting fired.”
How to Build a Heat Stress Plan for a Construction Site
A heat stress plan for a construction site is only as strong as the system around it. Dr. Eason’s framework, drawn from a task force convened in Washington, D.C. in October 2024 and co-sponsored by the National Athletic Trainers Association and Perry Weather, organizes construction heat stress safety into four areas: prevention, recognition, treatment, and return to work.
The task force brought together researchers, occupational health professionals, and athletic trainers to develop practical, evidence-informed recommendations for managing heat in occupational settings.
1. Prevention
Prevention is the most important lever for protecting workers and keeping projects on schedule.
“The most important thing to understand is that prevention isn’t one strategy, it’s a system.”
Dr. Christy Eason, Korey Stringer Institute
The system has several non-negotiable parts:
A written, practiced heat illness prevention plan
Every site needs a heat safety policy that is communicated clearly, in plain language, with visuals that make sense to seasonal workers, new hires, and contractors cycling in and out.
Heat stress monitoring
Heat forecasts help with scheduling ahead of time, but they do not replace real-time, on-site monitoring. Work-to-rest cycles should adjust based on actual conditions rather than predictions.
Access to hydration
Workers need clean, cool water nearby. Eason flagged something less obvious: workers also need access to clean, private restrooms.
“If there isn’t a restroom available, they might be less likely to drink, because they are worried about how they are going to be able to void.”
Dr. Christy Eason, Korey Stringer Institute
Cooling opportunities
Cooling should happen before and during the workday, rather than only at the end. Cooling towels, vests, fans, and air conditioning all help. Moving air through the workspace is one of the most effective controls available.
Buddy systems and check-ins
Workers should not be alone when it is avoidable. When solo work is necessary, clear check-in processes need to be in place so someone knows if something goes wrong.
Physiological monitoring
Wearable technology that tracks physiological indicators is an emerging tool for identifying workers approaching dangerous thresholds before symptoms become severe, provided it is implemented in compliance with health data and privacy regulations.
2. Recognizing Heat Illness
Even with strong prevention, things can still go wrong. When they do, recognition speed is the difference between a near-miss and a fatality.
“The difference between a good outcome and a bad one often will come down to minutes.”
Dr. Christy Eason, Korey Stringer Institute
Every worker and supervisor should be able to spot the early signs of heat illness: headache, nausea, dizziness, confusion, and hot skin. One point Dr. Eason emphasized deserves its own callout, because the misconception is widespread and dangerous. It leads supervisors to rule out heat stroke when they should be activating an emergency response.
3. Treating Heat Injury and Symptoms
If a worker collapses or shows signs of severe heat illness, the immediate priority is rapid cooling. Cold water immersion is the most effective treatment available and should begin while waiting for EMS to arrive. If a cold water tub is not on-site, use whatever cooling methods are available. A healthcare provider on-site can take a rectal temperature for accuracy, but cooling should not wait for that step.
Eason was clear that emergency action plans need to be in place long before anyone needs them. Every site should have a site-specific emergency action plan that is not only written but practiced at least annually. Everyone on site should know their role, how to activate a response, how to contact local EMS, and how to begin cooling immediately.
4. Returning to Work
When a worker is treated for heat illness, care does not stop at the hospital door. A structured, individualized, and progressive return-to-work plan protects both the worker’s long-term health and the project’s productivity.
“Recovery doesn’t stop when symptoms resolve.”
Dr. Christy Eason, Korey Stringer Institute
Athletic trainers can play a significant role in monitoring recovery and adjusting workload during the return-to-duty period. A prior heat illness does not permanently disqualify someone from working in the heat, but it does require careful monitoring and additional precautions during reintegration.
The Regulatory Landscape Is Catching Up Fast
OSHA’s General Duty Clause already obligates employers to protect workers from known hazards, and heat qualifies. A federal heat injury and illness prevention standard is currently in rulemaking. Seven states have enacted full or partial standards already.
Companies that wait for federal rulemaking to finalize before updating their construction heat stress safety programs are betting against the clear direction of travel.
“Client expectations, insurance, and litigation exposure are moving in the same direction.”
David Martin, PhD, Perry Weather
Martin’s prescription for closing the gap is short and worth memorizing.
“The solution with a lot of this is communication, mitigation, action, and monitoring.”
For construction leaders building or revisiting a heat stress plan for a construction site this year, the fastest path forward is to verify which protections their state already requires, audit their current policy against the four-pillar framework, and pressure-test whether the people on the ground actually know what to do on a 95-degree day.
What Construction Leaders Should Do Next
Heat stress in construction kills workers, drains productivity, delays projects, and creates significant liability. The data is clear, the framework is established, and the regulatory direction is set. What separates the companies who manage construction heat stress well from the ones still reacting after an incident is execution.
Three actions will move most companies forward this season:
- Audit the existing heat policy against the four pillars. If a section is thin or missing, fix it before peak summer.
- Translate the policy into worker-facing communication that seasonal hires, contractors, and Spanish-speaking crews can use without interpretation.
- Stand up real-time environmental monitoring with thresholds that automatically trigger work-to-rest adjustments, rather than alerts that get ignored.
Prevention is the goal. Recognition and treatment are the backup. Return to work is the finish line. The companies who treat construction heat stress safety as a system rather than a checklist are the ones who finish projects on time without sending workers home in an ambulance.
