Havenith G, Heus R, Daanen H A
TNO Human Factors Research Institute, Soesterberg, Netherlands.
Arctic Med Res. 1995;54 Suppl 2:37-47.
When a person is exposed to cold and his metabolic rate is insufficient to maintain a positive or neutral heat balance, the body will cool down. For the extremities this will result in a drastic reduction of blood flow, resulting in a so called "physiological amputation" with extremity cooling towards ambient temperature. The dexterity decrease observed with cold extremities is most likely caused by cooling of muscles and joints, and not by effects on receptors, nerve conduction or central effects. It is shown, that dexterity decreases can be described in terms of wind chill equivalent temperature and exposure time for a certain clothing and work configuration. Further, the risk of skin freezing and reduced dexterity due to touching cold objects can be described using the contact coefficient of the respective material and the contact time. This risk is modulated by metabolic rate and hand protection (gloves). Gloves drastically reduce cooling speed and freezing risk, but they also cause increased risks due to reduced dexterity due to glove thickness. For a general description of performance and risk of hand cold exposure in relation to climate and exposure time more data are needed.
当一个人暴露在寒冷环境中且其代谢率不足以维持正向或中性热平衡时，身体将会降温。对于四肢而言，这将导致血流量急剧减少，从而造成所谓的“生理性截肢”，四肢温度会降至环境温度。观察到的因四肢寒冷导致的灵活性下降很可能是由肌肉和关节冷却引起的，而非对感受器、神经传导或中枢的影响所致。研究表明，对于特定的服装和工作配置，灵活性下降可以根据风冷等效温度和暴露时间来描述。此外，由于接触冷物体导致皮肤冻伤和灵活性降低的风险可以通过相应材料的接触系数和接触时间来描述。这种风险会受到代谢率和手部防护（手套）的调节。手套能大幅降低冷却速度和冻伤风险，但由于手套厚度导致灵活性降低，也会带来额外风险。为了全面描述手部暴露于寒冷环境下的表现及风险与气候和暴露时间的关系，还需要更多数据。
