The Dangers of Heat Stress and How to Prevent It

March 16, 2020


The Importance of Heat Protection  

The summer months are fast approaching and crews all over are gearing up for prime outdoor work season. But as the temperature climbs, so does the risk of heat stress for outdoor workers.  

Heat stress encompasses a range of conditions: from heat rash and heat cramps, which can be uncomfortable and keep you from working, to heat exhaustion, which may put you in the hospital, to heat stroke, which could be fatal.  

At Pelsue, part of the reason we’re so proud of our SolarShade® series tents is the knowledge that they can contribute to worker safety in hot conditions. Of course, we want to be clear: there’s no substitute for having a plan in place to combat heat stress on the job.  

Before we hit the depths of summer, then, we believe it’s important to talk about heat-related risk factors, the conditions triggered by heat stress, and ways to treat a worker suffering from intense heat.  

This time of year means a huge increase in outdoor work. Let’s make sure it gets done safely.  

What is Heat Stress? 

Heat stress is an umbrella term for a number of conditions induced by exposure to a high heat index and physical exertion. There are several factors that contribute to heat stress, meaning it’s not quite as simple as looking at your thermometer.  

First, there’s the heat index. The heat index measures how hot it feels on exposed skin by combining air temperature and humidity. Being from Colorado, we’re keenly aware of the importance of humidity in relative heat—anyone who has traveled from here to the Midwest or coasts has felt the mugginess that comes from moist air. 

Say it’s a fairly hot day—90 degrees. With 40% humidity, the heat index equals 91 degrees. That may not seem like a huge change, but OSHA classifies a 91 degree heat index as moderate risk. This means sunstroke, muscle cramps, or heat exhaustion are possible with prolonged exposure and physical activity. 

Just 65% humidity on that same 90-degree day means a heat index of 103 degrees. At that point, the index crosses into high risk territory—meaning those conditions become likely, and heat stroke becomes a real possibility. Any heat index above 115 (say 90 degrees and 85% humidity) is listed as “Extreme Danger” meaning heat stroke is likely and outdoor work should be avoided. 

Different levels of physical exertion are similarly nuanced. Of the 20 OSHA citations documented in their latest report, all the workers in question were engaged in tasks classified as a moderate or higher workload. But those categories are frustratingly vague.   

OSHA does offer some guidelines here. Moderate physical labor may involve sustained hand and arm work, moderate pushing and pulling, or walking at a moderate speed. Examples include painting with a brush or picking fruits or vegetables. Heavy labor could include shoveling, sledgehammer work, or moving loaded handcarts or wheelbarrows.  

Since these are broad guidelines, the best bet to determine workloads on a given jobsite may be to consult OSHA’s guide on a case-by-case basis.  

Who is at Risk? 

Let’s start here with the bottom line: anyone who works in a hot environment is at risk of suffering from heat stress.  

Regardless of age, weight, gender, or type of labor, if you work outdoors in the summer, you are at some risk.  

Beyond that, there are a few groups of people who should be especially careful when their work takes them to a high-risk location.  

People with chronic illnesses such as heart or lung disease are at an increased risk of heat stroke. If a worker is aware of these conditions, taking extra precautions can be lifesaving. If a worker is unaware of a preexisting issue, exertion in high heat could quickly become lethal.  

Those taking medications for blood pressure (both to raise and lower blood pressure), diuretics, and antidepressants may also be at a higher risk in extreme conditions.  

Lastly, people who have consumed alcohol or illicit drugs are at very high risk of heat stroke—though it should go without saying that these substances shouldn’t be used on the job to begin with. 


Range of  Conditions 

Heat stress can induce a multitude of conditions, with a spectrum of implications for the affected worker. The following is based on the CDC’s heat stress guide.  

Heat rash is the least severe of these, and it’s basically what you’d imagine it to be. It’s caused when excessive sweat due to the heat, especially sweat trapped by layers of clothing, irritates the skin. When heat rash occurs, the best thing to do is move the worker to a cool location, dry the affected area, and apply powder for comfort. Creams or ointments are not recommended. 

Heat cramps are another condition that’s relatively  straightforward. Salt and moisture lost due to excessive sweating causes the muscles to seize in painful cramps. The best treatment is removal to a cool location, and for the worker to be given water and a snack or a sports drink. However, if the worker has a heart condition, is on a low-sodium diet, or has cramps lasting more than an hour, medical attention should be sought.  

Fainting due to heat is caused by dehydration and lack of acclimatization. Affected workers should rest in a cool, shaded area and slowly drink water or a sports drink to recover.  

Rhabdomyolysis is different from the other items on this list in that it’s a long–term condition. Rhabdomyolysis occurs when muscle tissue dies and releases its contents into the bloodstream. This can accumulate over time and cause serious kidney issues, including kidney failure. The long-term nature of the syndrome means that the best tool is prevention, which we will discuss more below. 

Heat Exhaustion is again caused by loss of body moisture through excessive sweating. Symptoms include headache, nausea, dizziness, weakness, and irritability. While it may not sound serious, stopping heat exhaustion is crucial because heat exhaustion quickly leads to heat stroke. The worker should be taken to a clinic or emergency room immediately.  

Heat stroke is the most serious of the heat stress-induced illnesses. In heat stroke, the body’s temperature rises so quickly the sweat glands are unable to respond and shuts down, meaning the body’s natural cooling mechanism is lost. Signs of heat stroke include confusion, slurred speech, hot, dry, or excessively sweaty skin, seizures, or loss of consciousness. The worker must be treated immediately or the illness is likely to be fatal. Stay with the worker until emergency crews arrive. Move them to a shaded or air-conditioned area. Wet the skin with cold water, or place them in a cold bath if possible and circulate the air around them to speed cooling. 

Preventing Heat Stress 

OSHA’s campaign to reduce heat stress is centered on three simple things: water, rest, and shade. Water resupplies fluids, rest decreases the strain of exertion, and shade lowers body temperature. Ensuring workers are staying hydrated, taking breaks, and have shaded areas readily available can mean a real difference for their health.  

Acclimatizing workers by gradually increasing levels of exposure over a period of 7-14 work days slowly builds their tolerance and reduces the chance that sudden heat will shock their systems, sending them into heat stroke. 

Lastly, make sure workers in hot environments are not alone greatly increases the chance that problems will be noticed and acted upon. 

Everyone here at Pelsue hopes the summer months bring you a lot of opportunities to work, and that you can do so in good health.   


Pelsue is your partner in ensuring a safe and secure work environment for your team.

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Aurora, CO 80019


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