Learn about cold stress and its effects on workers

As the weather gets colder, workers must stay protected from the elements. Freezing temperatures, along with snow and ice, can present significant health and safety challenges for your job site. One of the most common risks is cold stress, which can manifest in a few different ways.

Knowing about cold stress and how to prevent it ensures that your employees stay safe all season long. So, let's dive in and learn cold stress prevention tips.

What is Cold Stress?

The term "cold stress" actually describes several conditions brought on by low temperatures. As you know, the human body needs to stay at roughly 98.6 degrees Fahrenheit at all times. When exposed to a cold environment, the body struggles to maintain this temperature, causing the internal body temperature to go down. Cold stress happens when a person's body heat dips too far below the standard threshold.

What Causes Cold Stress?

Multiple factors can cause cold stress: low temperatures, strong winds, and dampness. Let's break down each element.

Low Temperatures

You might think that workers have to be in freezing conditions for them to experience cold stress. However, the reality is that it doesn't take much for the body to work hard to maintain its internal heat. Even temps in the mid-50s can cause cold stress symptoms, particularly if workers are exposed to high winds or wetness.

That said, the colder the environment, the easier it is for cold stress to occur. For example, workers in sub-zero temperatures need more layers of protection than those in 50-degree weather.

Strong Winds

When looking at the weather report, you may see the "wind chill factor." This factor affects the body significantly, as it can draw heat away fast. So, even if the ambient temperature is relatively high (i.e., 70 degrees Fahrenheit), strong winds can still cause cold stress. Wind and freezing temperatures are a dangerous combination since they can reduce one's body heat much quicker. Before heading out to a job site, workers can use the National Weather Service’s (NWS) wind chill calculator or chart (linked below) to determine how long they can safely work in such conditions based on the wind speed and temperature.

National Weather Service (NWS) Wind Chill Calculator and Chart

Dampness and Cold Water

Once again, workers don't need to be exposed to significantly cold water to experience cold stress. According to the University of Michigan, being in water between 60- and 70-degrees Fahrenheit is more than cool enough to draw body heat away. Prolonged exposure can have a much more serious effect and lead to conditions like trench foot and hypothermia (more on those in the next section).

Dampness doesn't have to come from standing or running water, either. Rain, ice, and snow can all seep into worker's clothing, causing them to get damp. Damp clothes plus cold weather conditions can lead to severe complications and health issues.

Symptoms and Types of Cold Stress

There are three primary types of cold stress: hypothermia, frostbite, and trench foot. Each condition shows unique symptoms, and workers can exhibit all three types of cold stress. Here's an overview of the signs and dangers you can expect:

Hypothermia

This condition occurs when the body loses heat faster than it can produce it. Hypothermia is when the body's internal temperature reaches 95 degrees Fahrenheit or below. At those temperatures, major organs can't work properly since the body struggles to warm itself. If left untreated, workers can go into shock and die as their hearts and lungs shut down.

Symptoms of Hypothermia

Shivering is the first sign of this condition, as the body tightens and relaxes its muscles to warm them. Mild shivering is okay, as long as the individual is still alert and active.

Once the body's temperature reaches 95 degrees or below, individuals will stop shivering and start showing confusion. Their speech may become slurred, and their heart rate and breathing will slow down. In severe cases, the person will become unconscious and unresponsive.

Frostbite

This condition happens when the skin starts to freeze. There are three stages of frostbite, as it can get progressively worse if left untreated.

Stage One: Frostnip - At this stage, the skin may become red and numb. This stage is not dangerous, and the skin will usually recover quickly when warmed up.
Stage Two: Superficial Frostbite - This stage is a bit more dangerous, as it can lead to blisters and temporary skin damage. During this phase, the skin will actually feel warm, which is a significant warning sign.
Stage Three: Deep Frostbite - The skin is deeply frozen and may become necrotic. The area will become completely numb, which can affect joints and muscle movement. If the skin turns black and hard, it's dead and may require amputation.

Typically, frostbite occurs around the extremities, such as the fingers, hands, toes, and feet.

Trench Foot (AKA Immersion Foot)

The name for this condition stems from World War 1 since it was commonly found in soldiers living in trenches. Immersion Foot occurs when the foot is submerged in water for extended periods. Even damp clothing and a wet environment can cause Trench Foot if the skin isn't aired out and dried regularly.

In extreme cases, the skin, muscles, and tendons can die, requiring amputation to prevent infection to the rest of the body.

Symptoms of Trench Foot

The first signs of Trench Foot are itching and tingling, followed by pain, swelling, and numbness. Even after the foot dries out, the skin may be red and blotchy for hours. You may also see blisters and dead skin flaking off.

Which Industries are Exposed to Cold Stress the Most?

As a rule, workers in outdoor environments can experience cold stress more than other occupations. However, employees can be exposed to freezing temperatures indoors as well. The top six industries that are exposed to cold stress include:

Construction
Mining
Utility Services (e.g., cable repair techs)
Sanitation (including garbage workers)
Truck Driving
Food Preparation and Distribution (walk-in freezers and coolers)

Treatment and Prevention Options for Cold Stress

Fortunately, cold stress is easily preventable as long as you follow some basic guidelines. Let's review some OSHA cold stress prevention tips.

Educate Employees and Supervisors

No matter the hazard, the first step to prevention is knowing what to expect. Workers should be aware of the symptoms of cold stress, including hypothermia, frostbite, and trench foot. This way, they can notify colleagues or supervisors when they start experiencing those symptoms. Otherwise, workers may try to "tough it out," leading to serious complications.

Supervisors should also be aware of how to handle these conditions if they occur. Here is what OSHA recommends for each ailment:

Hypothermia - Move the affected person to a warm area and cover with clean, dry clothing. Call 911 immediately. If help is more than 30 minutes away, apply heat packs to the armpits, neck, and groin area. If possible, have the person drink warm, sweetened beverages (non-alcoholic).
Frostbite - Workers should avoid touching or rubbing the affected area. Move the person to a warm place until they recover. In extreme cases, call 911 for medical treatment. Lightly cover the frostbitten skin to avoid further exposure.
Trench Foot - Air dry the affected area until it is no longer damp. Cover with clean, warm clothing and avoid walking. Contact 911 for medical attention.

Minimize Exposure to Cold Temperatures

Try to schedule work for the warmest part of the day. If that's not possible, reduce work periods so that employees are not exposed for more than a couple of hours. Rotate workers in shifts so that they can warm up in between.

Employers should also provide warm areas for employees. These locations should have heaters and blankets and be sheltered from the elements. In addition, warm, sweetened beverages (e.g., coffee, tea) can help maintain one's internal temperature, so these should be on hand at all times.

Wear Proper PPE

The best way to prevent exposure to cold temperatures is to have workers wear multiple layers of clothing and personal protective equipment. The number of layers will depend on the severity of the weather. Here's an overview of the various layers that may be employed:

Base Layer - This layer will touch the skin and provide the first level of protection. Ideally, workers will use moisture-wicking material to avoid damp and uncomfortable clothing. The base layer will transfer sweat to the other layers and away from the body.
Light Insulation Heavy Insulation - Examples can include a light jacket or sweater. This material should provide moderate insulation while still allowing for some airflow.
Heavy Insulation - Heavier jackets or sweaters will trap more body heat so that it doesn't escape. If necessary, workers should wear all three layers to protect themselves from extreme cold.
Windproof and Waterproof Insulation - This outer layer can protect employees from wind chill, rain, and snow. Even though the garment is waterproof, it should still allow for moderate airflow to prevent overheating.
Extremities - Workers should wear gloves, boots, and face coverings when working in cold environments. Balaclavas and warm facemasks can help protect the head. Workers should also wear hats or helmets to insulate themselves further.

Employers need to provide clean, dry protective clothing in case someone gets wet while on the job. If possible, there should also be a drying station where wet clothes can be aired out.

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Your Guide to Cold Stress and Its Impact on Workers