Brain freeze

Proper winter headwear helps limit risks of excessive cold exposure

s a competitive cross-country skier, Haley Kuppers learned first-hand the effects of extreme cold on the body. On the day of one race, the temperature was -18 C — plus wind chill.

“After the race, your lungs feel like they’re in pain because of the harsh cold they’re experiencing,” she recalls. “It bites your skin, and the higher humidity gives you that bone-chilling feeling.”

Kuppers, now a provincial health and safety specialist with the British Columbia Ministry of Energy and Mines in Victoria, says her experience of the cold remains a strong memory, reminding her always of the importance of knowing how to stay warm.

“That made sure that I would always go prepared to a mine site,” she says.

Workers who spend hours outside during the winter months must maintain their core body temperature at 37 C, according to the Canadian Centre for Occupational Health and Safety (CCOHS). It’s especially important to protect the head. The head, face and chest are more sensitive to temperature changes. And, although the head does not lose heat at a greater rate than do other parts of the body, exposure of the head speeds up cooling of the body’s core temperature.

Excessive exposure to cold, or cold stress, can cause serious health effects, most commonly frost nip (freezing of skin surface), frostbite (freezing of and damage to skin and other tissues) and hypothermia (cooling of the body below the temperature required for normal metabolism). 

A basic component of training for those working in extreme cold is a thorough knowledge of the effects of frostbite and hypothermia, says Mike Russo, occupational hygienist with the Infrastructure Health and Safety Association (IHSA) in Mississauga, Ont. Workers should be trained to recognize the signs and symptoms of these illnesses in themselves and their co-workers.

Frostbite usually affects the face, ears, fingers and toes, he says. The skin may start to feel numb, becoming bluish or pale and developing a sharp, prickly sensation.

In its early stages, Russo says, hypothermia is characterized by shivering, fatigue, loss of co-ordination, confusion and disorientation. In severe cases, shivering may stop, the skin becomes blue, the pupils of the eyes dilate, and breathing and pulse slow down. A person can eventually lose consciousness.

Workers should also know how to recognize and assess factors that increase the risk of cold exposure, such as immersion in water (due to rain or standing in water), Russo says. They should be able to determine when it’s too cold to work, including knowing how to take note of the temperature and the wind chill — a combination of the wind, temperature and the cooling effects on the skin.

Training for cold weather should also cover the kind of protective clothing most effective in keeping workers warm. The key is to dress in layers, says Jan Chappel, senior technical specialist at CCOHS in Hamilton.

“You want an outer layer that’s windproof and a middle layer of some kind of wool or quilted or synthetic fleece as an insulator,” she says. “Your inner layer should be of something that will let moisture wick away from your skin.”

Layering allows workers to remove clothing, thus avoiding getting too warm and sweating — moisture on the skin, from sweat or rain, cools the body down.

“You can open a jacket, take a layer off or take off your head toque if you need to. The idea is to have the flexibility to put it back on and take it off as activity changes,” Chappel says.

When the wind chill is high, the corneas of the eyes may freeze, and eyes should be protected with goggles, shields or glasses. According to CCOHS, eye shields should be separated from the nose and mouth to prevent breath moisture from fogging or frosting the lens.

Kuppers agrees managers should inform workers about the kind of personal protective equipment (PPE) they should wear. Like all effective winter clothing, she says, headwear should not be tight-fitting (which may reduce circulation) and should be made of a material that is breathable but doesn’t retain moisture. Workers should also wear a neck-warmer and rain gear to keep the head dry.

Because miners are required to wear hard hats, Kuppers says, they keep their heads warm by adding inserts specifically designed to be worn under the hats.

Winter liners are common in many industries, including construction, oil and gas, utilities and fire departments.

Simon Levin, Canadian sales manager for Seattle-based Dragonwear by True North, which makes fire-resistant beanies for wear under hard hats, says a person cannot get warm when clothing against the skin is wet.

“So what a good beanie will do is keep the head dry. It will wick the moisture away and stop the sweat,” he says.

The fabric used to make Dragonwear garments, he explains, is knitted so that the inner layer is hydrophobic (repelled from water) and the outer layer is hydrophilic (attracted to water).

“(This construction) pushes moisture to the front of the fabric, away from the skin, and makes it spread fast. The faster it spreads, the wider it spreads, and the faster the heat from your body can dry out the fabric,” he says.

Russo says workers who wear a toque or liner under a hard hat must make sure it does not reduce the protective capabilities of the hat.

“Usually, the suspension can be adjusted, so you want to make sure it fits snugly, so it doesn’t fall off or is not loose and that it fits snugly around the crown of the head.”

Baseball caps, he adds, should not be worn under hard hats because the cap will affect the hat’s suspension.

Mark Ciufo, co-ordinator for standards and occupational health and safety at the Canadian Electricity Association, says electrical workers are trained to wear the appropriate PPE. Winter undergarments must be made of natural fabric to increase warmth and comfort. Workers also wear hard hat liners and balaclavas, which cover most of the face, often including the nose, reducing heat loss from the face and the chance of frostbite.

At Canada Post, smaller vans, introduced as part of a new delivery system, provide extra and nearby shelter for carriers. Winter dress code includes not only a parka, gloves, cold-weather pants and a good pair of socks but also a toque or other head covering and neck and face protection, says Phil Legault, manager of media relations in Ottawa.

And in extreme weather, the supervisor makes sure carriers are properly dressed when they leave for their routes.

To help prevent cold-related illnesses, Kuppers says, managers can take measures such as requiring employees to carry a “care package,” a kit of extra clothing, rain gear, blankets and high energy foods.

Workers can reduce risk by staying properly hydrated and in good physical condition. On the job, they should carry a thermometer and hot packs.

“If you notice symptoms of cold stress, you can put on an extra layer and get a hot pack for your gloves or boots,” she says.

In Canada, many jurisdictions do not have direct regulations regarding when it is too cold to work, Chappel says. Most follow the threshold limit values (TLV) “work warm-up schedule” for outside workers published by the American Conference of Governmental Industrial Hygienists.

“It takes into account temperature and wind speed and recommends how long you should work outside and how many breaks there should be,” she says. “In some provinces, they are required to follow that. In other provinces, it is best practice.”

Chappel says dressing for the cold is often a challenge. Above all, it’s about being aware of changes in temperature, weather conditions and activity.

“And be ready to adapt,” she says. “It’s not day by day. It’s hour by hour, even job by job — be ready to adjust and know when to say, ‘it’s cold’ or ‘so-and-so looks like he’s struggling. We need to get him into first aid and see what’s going on.’ ”

Linda Johnson is a freelance writer based in Toronto. She can be reached at [email protected].