How Wind Chill Affects Our Bodies

The skin is our largest organ and is vital in temperature control.

When hot we sweat, which removes excess heat and so cools us. To keep warm, the skin warms a thin insulating boundary of air, trapping in body heat.

Wind cools the skin in two ways, firstly by disturbing the insulating boundary layer of air, and secondly by increasing the evaporation of moisture from the skin that takes body warmth with it.

Wind chill below -50°C on an exposed forehead can result in unconsciousness in minutes, while skin may freeze within 30 seconds in a wind chill of -75°C.

Individual differences
It is based on heat loss from the average person; however there are a number of physiological factors that can cause variability in how we feel in a cold wind.

Extreme cold can cause both frost bite and hypothermia. Depending on your build, you can be more susceptible to one than the other.

Tall thin people tend to feel cold sooner than their stockier counterparts as they have a greater surface area of skin compared to their mass. People with greater insulation are more susceptible to frost bite but less susceptible to hypothermia, as they lose core body heat to their cooling skin more slowly.

The young and the elderly have less developed and less effective body temperature control systems, so they are at particular risk from the cold. Many schools in Canada, where wind chill effects are very important, have a 'Cold Weather Policy' where children are kept indoors when wind chill reaches a certain level.

Those with damaged blood vessels, which carry heat around the body, are also more susceptible to the cold. Smoking and drinking alcohol can both lead to an increase in the likelihood of frost bite if exposed to extreme cold.

Metabolism rates can also have an impact on how cold you feel, as slow metabolism can result in poorer circulation.

Certain medical conditions, or even medications, can also have an effect on how we feel in a cold wind.

People with diabetes who have peripheral neuropathy (a disorder of the nerves) may find that they sweat more on their face and neck - from which we lose a large proportion of our body heat. High blood glucose levels can also damage the nerves in legs and feet, which means that cold may not be felt as easily - leading to an increased likelihood of frost bite in extreme cold.

Taking Beta-Blockers can also increase the likelihood of frost-bite as they cause constriction of blood vessels, and this results in colder hands and feet.

Avoid the cold
Apart from staying inside on windy days, there are simple things that you can do to lessen the effects.

Hydrate your skin inside and out by drinking plenty of water (dehydration affects your ability to regulate your body temperature) and applying a moisturiser to wet skin to seal in moisture and help prevent heat loss.

Wrap up well - a hat and scarf can help keep in the 40 - 50% of heat lost through the head and neck, mittens help keep hands warmer than gloves, and several thin layers of clothes help create more insulating layers of boundary air. A scarf over your mouth can stop extreme cold entering your lungs that can then remove heat on exhalation.

Eating a light snack rather than a big meal before going out means that less blood is diverted to the stomach to aid digestion and so more is available to circulate to fingers and toes.

Wearing waterproof clothes in wet weather prevents the increase in heat loss from damp skin and clothes - heat loss is about 20 times faster from wet clothes than dry clothes.

In strong wind, the body can react as if it is under attack - creating the 'stress hormone' dopamine. The body can't sustain stress like this for long, which is why we feel exhausted at the end of a windy day.