Paradox: increased blood perfusion to the face enhances protection against frostbite while it lowers wind chill equivalent temperatures

• Published in: International journal of biometeorology Vol. 51; no. 5; pp. 383 - 393
• Main Author: Shitzer, Avraham
• Format: Journal Article
• Language: English
• Published: United States Berlin/Heidelberg : Springer-Verlag 01-05-2007; Springer Nature B.V
• Subjects: Air temperature; Blood circulation; Body Temperature Regulation; Cold; Cold Climate - adverse effects; Cold environment; Cold weather; Conduction heating; Conductive heat transfer; Convective heat transfer; Equivalence; Face - blood supply; Facial blood perfusion; Frostbite; Frostbite - etiology; Frostbite - physiopathology; Frostbite - prevention & control; Heat; Heat exchange; Heat loss; Heat transport; Humans; Injuries; Models, Biological; Models, Statistical; Perfusion; Regional Blood Flow; Skin - blood supply; Skin temperature; Wind; Wind chill; Wind speed; Wind velocities
• ISSN: 0020-7128; 1432-1254
• DOI: 10.1007/s00484-006-0082-3

A model of facial heat exchange in cold and windy environments is presented. The tissue is depicted as a hollow cylinder and the model includes heat conduction and heat transport by blood circulation from the warmer core. A steady-state solution facilitating the estimation of wind chill equivalent temperature (WCET) as a function of the effective wind velocity, air temperature and blood perfusion rate was obtained. The results quantify and demonstrate the elevation of skin temperatures caused by increased flow of warmer blood from the inner core to the face. Elevated facial temperatures, while enhancing protection against frostbite and other cold-related injuries, also increase heat loss to the colder environment. Paradoxically, such elevated facial temperatures cause WCETs, as estimated by the prevailing definition, to attain lower rather than higher values, indicating, in fact, increased risk of frostbite. The results of this study should be useful in understanding and quantifying the effects of blood perfusion in protection against cold-related injuries. They should also be considered in the re-evaluation and re-formulation of the concept of wind chill, which has been a useful cold weather indicator for decades.