Guest Article
December 2001

Working and Playing in the Cold
This timely article was written by my friend and colleague Mike Harnett of WorkSmart Injury Prevention Systems Inc.

Dressing for the Cold
In this part of the country, the unpredictability of the weather is an accepted daily occurrence. When you are too cold, too hot, or too wet, it is difficult to concentrate on the task at hand, therefore it is important to dress for changes in temperature. Dressing in layers can prevent uncomfortable temperatures by allowing you to adjust to a wide range of conditions. The proposed layers will be lighter, eliminating the bulkiness of some winter wear, while still providing the warmth necessary to survive the cold.

Inner-Layer
The most critical layer (underwear) is in direct contact with the skin and therefore must transport body moisture away from the skin and disperses it to the next layer to be evaporated. Wet clothes against the skin draws heat away twenty-five times faster than dry clothes, rapidly decreasing the body's core temperature, leading to hypothermia.

Synthetic fabrics such as polypropylene and polyester are they best choices for this layer as they are light, strong and absorb very little water, helping to reduce heat loss. Cotton is not recommended. For "stop and go" activities mid-weight, synthetic underwear provides moisture control and insulation. For colder conditions, the best bet is a heavy-weight underwear for maximum insulation. They should fit snugly, but not be restrictive.

Mid-Layer
This layer's purpose is to provide insulation and transport moisture from the inner-layer. To minimize heat loss this layer should be capable of holding on to the heat that the body generates. Wool and synthetics are good fabrics to use because the fibre structures create small air spaces that trap molecules of warm air. Wool absorbs up to thirty percent of its own weight in water, which can make it heavy and hard to dry. Synthetics absorb less water, evaporate faster, are lighter and require less care, making it the better choice. For colder weather, mid-weight or heavy-weight fleece are good options.

Outer-Layer
This shell protects you from the weather, allowing the air to circulate and excess moisture to escape. For dry conditions, a breathable (uncoated) wind shell may be all that is necessary; in more severe conditions, a waterproof rain jacket. A shell made of a breathable and waterproof fabric like Gore-Tex ® gives protection from wind, rain and snow and allows the water vapor to escape.

Under heavy physical exertion, the body produces more water than any fabric can disperse, making it necessary to manage the layers by stripping off a layer or opening ventilation zippers. This will prevent a build-up of moisture on the inside of the garment, which could leave you wet, clammy and cold.

Head, Fingers & Toes

Head Proctection: Up to 50% of a person's total heat loss occurs through the head. This heat loss puts a strain on the rest of the system because the body must use additional energy to rewarm the blood as it circulates. A good wool or fleece liner will slow heat loss via the head, but will also keep hands and feet warmer because of the improved circulation. In extremely cold conditions, a full-face balaclava or a neck guitar can also help keep the heat in.

Hands & Feet: In an attempt to maintain the temperature of the head and vital organs, the heart reduces blood flow to the hands and feet. Insulation and protection from the outside elements is necessary. Mittens are warmer than gloves but inhibit dexterity. A layering system of a thin wool or synthetic glove for moisture transport, an insulating mitten and a non-insulated shell mitten for outer protection will give a wide range of temperature control and manual dexterity.

It is very important to keep feet warm and dry. Wool is the preferred material as It provides moisture management, warmth and cushioning. Adding a polypro liner sock will speed up moisture transport from the feet to the outer wool area. A sock with a wool/ acrylic/stretch nylon/polyester blend is also a good choice. Socks should fit snugly, but not too tight, inhibiting circulation. Proper airflow around the foot increases heat retention.

With thanks to Mountain Equipment Co-Op for their assistance.

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