Ski season is upon us. There is no greater relief on a frigid winter day than warming cold, painful fingers and toes. In a recent issue of Wilderness and Environmental Medicine (2009;20:33-38), William Sands, Ph.D. and colleagues authored an article entitled, “Comparison of Commercially Available Disposable Chemical Hand and Foot Warmers.” The objective of their study was to characterize the thermal behaviors of 14 commercially available hand and foot warmers.
The warmers were studied in pairs in a laboratory setting, not in frigid conditions. Each warmer was monitored with a rapidly-responding thermister to determine its external temperature. One of each pair of warmers was placed in a boot or glove. Temperature was recorded until the heat output of the devices ceased and the temperature was determined to be identical to ambient temperature.
The results were quite interesting. There was variability both within and between manufacturers and types of warmers. Some of the devices exceeded packaging claims, while others fell short. The greater the mass of the warmer, the longer the duration of heat production. Read more »