Summer presents the challenge of working in blistering heat, but now is the time of year to begin focusing on the dangers of working in extreme cold.
When cold stress sets in, your tough jobs get even tougher. To protect against injury, illness and loss of life or limb, contractors must understand the causes and consequences of cold stress.
The risks of cold stress
Cold stress is a condition in which the body responds to cold environments by drawing blood away from the extremities and into the core to maintain sufficient warmth for the vital organs to function. As the skin cools and blood retreats farther from the hands, arms, feet and legs, the risk of more serious issues like frostbite and hypothermia grows.
Anyone who works in the cold is at risk. But people with pre-existing health conditions like high blood pressure, diabetes, or certain thyroid or circulatory conditions are at greatest risk. And conditions don’t have to be extreme to feel the effects of cold stress. It can happen in relatively mild temperatures around 50 degrees F, especially when it’s windy, rainy or snowy.
Warning signs of cold stress include shivering, fatigue or drowsiness, and a tingling sensation followed by numbness. Cold stress becomes a medical emergency that requires immediate treatment when symptoms advance to disorientation or confusion; slurred speech; changes in skin color, such as turning from red to purple to white; and changes in skin texture, such as a waxy appearance.
Workers experiencing cold stress symptoms are a danger to themselves and, when they’re operating tools, equipment or vehicles, they become a danger to everyone else on the job site.
Preventing cold stress
The first step in preventing cold-related injuries and accidents is to monitor weather conditions and adjust work accordingly. The National Institute for Occupational Safety and Health recommends scheduling relief workers or assigning additional workers to jobs that are particularly demanding or that require peak concentration and high levels of dexterity or precision when conditions are extremely cold, wet or windy.
Next, workers in exposed areas should also take warming breaks in a heated area that is sheltered from the weather, such as a construction trailer or vehicle. The length of time workers should be in the cold and the frequency and duration of their warming breaks vary based on the temperature, wind chill and precipitation. A good rule of thumb is to take a 10-minute warming break between short periods of work.
Finally, the most important precaution workers can take is to choose the best-insulated workwear for the conditions on the job site.
How cold kills warmth
No matter what work you’re doing — digging trenches, connecting waterlines, or repairing a pump — cold comes to steal warmth in the following ways:
Radiation
Body heat rises to the surface of the skin and radiates away, especially in areas of the hands, head and neck where skin is more likely to be exposed. Keeping skin fully covered, head to toe, helps keep heat close to the body.
Convection
Commonly known as “wind chill,” convection amplifies the effects of heat lost through radiation by blowing away the layer of warmer air around the body. Choosing windproof outerwear will keep heat from blowing away with winter winds.
Evaporation
Working up a sweat sounds like a good way to keep warm, but remember that sweating is actually the body’s mechanism for cooling off. The process of sweat evaporating from the skin makes the body feel colder. Wearing multiple light and moisture-wicking layers keeps skin dry and allows workers to adjust the level of warmth when demands of the job require a change in activity level.
Respiration
In extreme cold, the simple act of breathing can be dangerous. Long exposure to breathing frigid air can lower the body’s core temperature. Covering the nose and mouth with a face mask, balaclava or gaiter can mitigate the effects of cold stress from respiration.
Conduction
Contact with cold surfaces, such as concrete slabs, metallic tools and equipment, and frozen ground, conducts cold into the body. Wearing thermal work gloves and insulated work boots with composite safety toes, rather than steel or aluminum, reduces the transfer of cold from surfaces and objects workers touch.
Dressing for the cold
When working outdoors or on unsheltered job sites, you need protection from the cold and the elements. Look for work coats or coveralls made with wind- and water-repellent fabrics, such as coated polyester or polyester with an inner weatherproof membrane. These guard against wet and windy weather while also adding durability against wear-and-tear on the job.
Next, consider the level of insulation needed for the range of temperatures experienced on the job site. Some manufacturers conduct thermal testing to determine the range of cold temperatures an insulated garment can protect against. Look for temperature ratings in the description or labeling on a garment.
If temperature ratings aren’t provided, workers can compare insulated work jackets and coveralls by the density of the insulation each garment contains. Insulation density is usually expressed as “g” or “gsm” to stand for grams per square meter. Thermal workwear made with high gsm insulation will be warmer than workwear made with lower gsm insulation.
Beyond density, workers should choose the type of insulation in their workwear with care, as well. The natural down insulation often found in a regular winter coat or parka might be warm at first, but it gets heavy when it gets wet. It also settles into clumps with long use, leaving “cold spots” in the garment.
Synthetic insulation, such as polyester or plant-based materials, can be sewn into the garment to avoid shifting and settling, increasing its durability. It’s also more resistant to moisture and weighs less than natural down insulation.
It’s also smart to choose winter workwear with insulating lining materials, such as graphene, which use nano-thin fibers to absorb escaping body heat and reflect it back to the wearer. These materials make a garment feel warmer without adding weight or bulk.
Workers should also consider their personal physiology and activity level. Age, metabolism, body composition and hydration levels affect how the body handles cold. Workers with special health concerns, like hypertension and other circulatory problems, will likely need more insulation in their workwear to feel comfortable in the cold. Workers who are more active, such as manual shoveling, will need less insulation in their cold weather workwear than one who moves less while operating a trencher or skid-steer.
Finally, all workers should dress in several light and breathable layers. A good strategy is to start with a moisture-wicking base layer. Avoid cotton base layers and thermal underwear, because cotton absorbs sweat and makes the body feel colder. Then add an insulated mid-layer, such as a thermal hoodie. Top it all off with a weatherproof outer layer such as an insulated jacket, bib overalls or coveralls.
While it’s important to wear enough layers to keep warm, remember that overdressing can be just as dangerous as underdressing. Wearing gear that is too warm causes excessive sweating, putting workers at higher risk for cold stress and hypothermia. Overbundling also gets in the way of doing the job. If a workers is wearing so much gear that it weighs them down and limits their ability to move, then they can’t do the job safely or effectively.
Protect the extremities
Covering the core and limbs is critical, but workers should also remember to protect their feet, hands and heads from the cold.
Wear moisture-wicking socks with waterproof work boots for maximum warmth. In wet weather or when work heats up, change out of sweaty socks during a warming break. For maximum comfort, look for work boots with a shock-absorbing cushion in the insole.
To protect hands from the cold and from the hazards of the job, gloves with articulated impact-protection pads — meaning each section of the finger has its own pad, with a gap or flex-panel across the joint — offer protection against bangs and pinches without restricting dexterity. It’s also helpful to look for insulated work gloves with individual side gussets sewn between each finger. Gloves with this type of construction deliver insulation around each finger separately, allowing for greater warmth.
Most workers will find that a thermal beanie or full-face mask is sufficient to protect the vulnerable tissues of the ears, nose and face from frostbite. Those who work on job sites requiring a hard hat or safety helmet should look for specially cut hard hat masks with extra openings that slide over the brim to cover the ears, face and neck.
About the Author
Leigh Stadelmeier is an authorized OSHA outreach trainer and vice president of B2B Outdoor Sales for RefrigiWear, a leading manufacturer of industrial insulated workwear, safety apparel and PPE for extreme cold work environments. Having experienced a traumatic fall while serving in the Army, Stadelmeier devotes his career to sharing safety gear and training to prevent accidents on the job.
