Protection of feet in cold exposure.

The paper summarizes the research on cold protection of feet. There exist several conflicting requirements for the choice of the best suited footwear for cold exposure. These conflicts are related to various environmental factors, protection needs and user comfort issues. In order to reduce such conflicts and simplify the choice of proper footwear the paper suggests dividing the cold into specific ranges that are related to properties and state of water and its possibility to penetrate into, evaporate from or condensate in footwear. The thermo-physiological background and reactions in foot are briefly explained, and main problems and risks related to cold injuries, mechanical injuries and slipping discussed. Footwear thermal insulation is the most important factor for protection against cold. The issues related to measuring the insulation and the practical use of measured values are described, but also the effect of socks, and footwear size. Other means for reducing heat losses, such as PCM and electrical heating are touched. The most important variable that affects footwear thermal insulation and foot comfort is moisture in footwear. In combination with motion they may reduce insulation and thus protection against cold by 45%. The paper includes recommendations for better foot comfort in cold.