Are Heat Edemas a Safety Issue?

By Karoly Ban Matei
Last updated: June 11, 2024
Key Takeaways

A heat edema may not be a serious condition, but it can be a warning sign for something more severe.

Anyone working in hot environments is at risk of developing a series of heat-related illnesses.


Indoor work conditions are more predictable and not likely to change substantially, which makes high heat easier to anticipate and control. Outdoor conditions, however, are far less predictable, especially as extreme heat events (heat waves) become more and more common.

When heat exposure brings the body to a point where it is no longer able to cool itself, that’s when heat-related illnesses set in. Most people are familiar with heat stroke, but there are others worth knowing about as well.


In this article, we’ll go over one of these, heat edemas. We’ll explain what they are, what causes them, and how to approach them from an occupational safety standpoint.

(Learn more in Heat Stress: Indoors vs. Outdoors)

What Is a Heat Edema?

Heat edema is characterized by substantial swelling in parts of the body, generally in extremities like the legs and hands. The swelling occurs after sitting or standing for extended periods of time in a hot environments.

Heat edemas belong to the category of less serious heat-related issues, along with heat rashes and heat cramps. These can be uncomfortable, but they have no severe or permanent outcomes.

What Causes Heat Edemas?

The mechanism behind a heat edema is a combination of gravity and vasodilatation.



The further from the heart a body part is, the more cardiac effort is required for blood to pump to that area and then return to the heart. Because of this, blood has a tendency to pool in the body’s extremities and create extra pressure on those veins and arteries. That pressure is responsible for the tingling feeling in your arm or leg when you stand still for too long.


Vasodilatation is the body’s first and most efficient cooling mechanism.

When it gets hot, the blood vessels dilate. This serves two functions:

  1. Increasing blood flow to the extremities and bringing the blood closer to the surface of the skin
  2. Thinning the blood vessels to make them more permable

These two processes work together to allow excess heat to escape the body through evaporation.

Gravity + Vasodilatation = Heat Edema

The pressure created by gravity combined with the increased permeability of the blood vessels makes fluid migrate through the walls of the blood vessels. That fluid then pools close to the skin’s surface, resulting in swelling.

And that, in short, is a heat edema. It’s swelling caused by the movement of fluid into the extermities. It typically affects the hands, legs, arms, and ankles, but can occasionally cause swelling in other areas as well.

Symptoms of Heat Edema

A heat edema is fairly easy to recognize. If working in a hot environment, the following symptoms are a good indication that a heat edema has set in:

  • Visible puffiness or swelling in arms, legs, wrists, or ankles
  • Arm or leg that feels full or heavy
  • Watch, jewelry, clothing, or PPE feeling tighter than usual
  • Pain or tautness in the swollen area
  • Skin that is visibly stretched and has a shiny appearance
  • Pressing on the swollen area leaves a persistent dimple in the skin
  • Difficulty moving to the affected body part (generally difficulty or discomfort when walking)
  • These symptoms can sometimes be accompanied by an increase in the abdominal area due to fluid retention

(Learn about 6 Serious Consequences of Heat Stress)

How to Treat a Heat Edema

A heat edema will generally easily resolve itself when the worker moves to an area with a lower temperature. Besides moving to a cool, shaded place, we can speed up recovery by:

  • Elevating the affected area to accelerate the drainage and reabsorption of the fluid
  • Using compression stockings to put pressure on the legs and prevent fluid from accumulating

Are Heat Edemas a Concern for Workplace Safety?

While a heat edema is not a severe medical condition and in itself would not degenerate into a recordable illness or injury, it should not be ignored. Rather, a head edema should be treated as a potential warning sign for the following:

  • The body struggling to cool itself. Continued exposure to heat will not only aggravate the edema, but could lead to more severe conditions like heat exhaustion or heat stroke. Consider the heat edema a near miss and move the affected worker out of the heat.
  • Other underlying conditions, especially in mild heat or when no other members of the crew are exhibiting symptoms. This could be due to a worker not being fully acclimatized, being pregnant, taking certain medications, or one of the following conditions:
    • Heart Failure: because the heart can’t pump blood to the body properly, workers with heart conditions are more likely to develop heat edemas
    • Diabetes: excess glucose in the blood results in damage to small blood vessels, which predisposes the body to accumulate fluid
    • Kidney Disease: kidneys remove excess fluid and maintain fluid levels in the body

A heat edema, then, should not be taken lightly. Depending on the circumstances, the affected worker may simply need to move away from the heat or they may need to follow up with a medical professional.

Hazard Controls for Heat Edemas

Similar to any other workplace hazard, there should be controls in place to minimize the risk of heat edema. Since most of these recommendations are about managing heat exposure, they will help keep workers safe from other, more serious heat-related illnesses as well.

Here are common recommendations that can be implemented immediately.

  • Acclimatization. The body can adapt to warmer weather, but this process takes time. Start with shorter work periods in hot environments and increase the duration of the work gradually.
  • Institute frequent breaks. Make sure that workers frequently remove themselves from the hot environment by providing breaks in a climatized office or a shaded area.
  • Encourage movement. Standing or sitting still for an extended period of time will cause blood to pool into the extremities. Encourage workers to alternate their position or take a walk to increase blood circulation.
  • Provide access to drinking water. In addition to keeping workers hydrated, drinking water also helps flush extra fluids from the body.
  • Reduce salt consumption. Sodium helps the body retain water, which increases the risk of an edema.
  • Workers with any of the medical conditions listed above should avoid working in the heat. Not only are they at a higher risk of developing a heat edema, but the heat itself can be a risk factor for those underlying issues.

(Find out Why You Should Always Let Your Workers Acclimate to the Heat)


A heat edema may not be a serious medical condition, but it should still be taken seriously. It can be an indicator of more serious problems, including a greater risk of developing other heat-related illnesses.

Treat heat edemas as a health hazard and implement control measures to eliminate the risk. if a worker develops a heat edema, they should cease working and rest in a cool area. If there are reasons to suspect the edema might be due in part to an underlying condition, encourage the worker to follow up with a doctor.

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Written by Karoly Ban Matei | HR and Safety Manager

Karoly Ban Matei

Karoly has worked at a senior level (both as an employee and a contractor) for organizations in the construction and manufacturing industries. He has a passion for developing and improving health and safety programs.

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