Hypothermia and outdoor workers: How to chase the chill away

Tuesday, January 07, 2014

Once wet, cotton and goose down actually make you feel colder

For most people, the winter naturally brings a chilly feeling. There are cold walks to and from work, a frigid feeling while pumping gas, or a chilling wind while shovelling snow. These cold shocks don’t often result in serious cold illness because, for the most part, a warm building, dry clothes, and a hot meal or drink is never far away.

While the cold can almost be a non-issue while living and working in a busy city – working outdoors can leave workers susceptible to illnesses like hypothermia. Due to the long-term effects and potential fatalities of cold illnesses, a few ounces of prevention are worth a pound of cure. Dressing properly, eating properly, and keeping an eye on each other are the best ways to prevent hypothermia.

Dress the part: Avoid cotton and goose down

Group of workers meeting outdoors in winter landscape

While working outdoors, clothing is your single most important resource to keep warm. Dressing in loose-fitting layers is essential. The layers trap heat easily and allow you to adjust your clothing as your activities change throughout the day. If you are overdressed you will work up a sweat as the day progresses. This will feel warm until activity stops and the sweat starts to cool your body down. It’s important to wear enough layers during activity to keep warm without sweating excessively, and then add layers when you start to engage in less strenuous activity. 

Layers should be made of fabrics that retain warmth when wet, such as wool, polyester fleece, and polypropylene (often found in synthetic long-johns). Cotton is quite possibly the worst fabric to wear for warmth in winter. Once it gets wet (from rain, snow or sweat), the cotton will start to extract heat out of the body. The effects can be particularly noticed in cotton socks, underwear, or when a cotton t-shirt is the first layer next to skin. Goose down is an excellent insulator when dry, but because it loses almost all its insulating power when wet, it is best to avoid during a Canadian winter.

Layering Systems: 

To work comfortably outside, a layering system should be applied to pants, socks, jackets, gloves and hats. It starts with a wicking layer to remove moisture from skin. From there it builds into heavier and more durable fabric to keep you warm.

Diagram of winter clothing layering system

Wicking Layer: This is the layer next to your skin. This layer should remove moisture from the skin and transfer it to the next layer, to avoid your body cooling down due to sweat. Recommended layers are synthetic or polypropylene long johns, tops and socks. Do not use cotton!

Light Insulating Layer: This goes on after the wicking layer. A light fleece or thin wool sweater is an excellent light insulating layer.

Heavy Insulating Layer:  A heavier fleece or wool sweater begins to trap heat in the body.

Windproof-Waterproof Layer: This protects your body from the weather conditions from wind to rain or wet snow. 

Winter Toque: Thirty to fifty per cent of body heat is lost through the head. A winter hat adds as much warmth as all your layers. In winter conditions, everyone should be wearing a toque. Balaclavas can be worn under toques and are excellent for protecting facial tissue from frostbite.

Gloves and Mitts: Mitts are warmer than gloves but not always practical for work that requires detail. To help with this problem, a thin glove can be worn inside a mitt. This will allow you to remove your mitts for more technical work while not exposing bare skin to the cold. Once done your work return your gloved hands promptly to your mitts. 

Socks and Gaiters: A two-layer sock system is most recommended for winter travel. A thin polypropylene sock with a wool sock over top allows moisture to be wicked from the feet and wool will stay warm even when wet. If wearing hiking boots in the bush, gaiters are highly recommended. They prevent snow sliding down into the boots and add warmth by trapping air. Gaiters go on outside of the boot and pant leg and are great for keeping snow from entering boots

Fuel your body: Go ahead and eat up!

Working outdoors requires your body to produce heat to keep you warm. Due to the extreme conditions, recommended calorie intake for winter work is 4,000 to 5,000 calories a day. It’s best to take in these calories steadily over the day. Six to eight snacks are far better than two heavy meals. Fifty per cent of these calories should be made out of carbohydrates such as bread and bagels. Cheese, butter, and meats add a valuable fat content to help keep your body warm.

Hydration is also very important in winter work. On average, four litres a day of water or fluids should be consumed. If you only have a one-litre water bottle with you during the day, make sure to consume lots of hot drinks at breakfast and dinner. Drinks with caffeine (coffee or soda), or alcohol should be avoided. Caffeine and alcohol restrict blood vessels, impeding the body’s ability to heat itself.  In the cold, water bottles will need to be insulated to prevent freezing. 

The Buddy System: Look for signs of hypothermia

If someone in your group has begun shivering, they have mild hypothermia. Hypothermia is easiest to treat at this stage, so steps should be taken immediately. At this stage, food and dry clothing are your best sources of treatment. A hot drink or meal can do a lot to add heat to the body. An extra layer, hat, or balaclava can capture additional heat leaving the body. Keeping an eye on each other is the best way to ensure that mild cases of hypothermia are nipped in the bud and do not have the chance to progress to moderate or severe hypothermia. 

Working outdoors in the wintertime can be a great experience, just make sure you’re dressed properly, have adequate food, and keep an eye on your team members.

Related information

Is there a temperature at which work becomes dangerous and should be stopped? Canadian Centre of Occupational Health and Safety 

White out! Winter driving tips – on and off the job Workplace Safety North