Department of Physical Therapy, Loma Linda University, Loma Linda, CA 92350, USA.
Med Sci Monit. 2012 Apr;18(4):CR201-8. doi: 10.12659/msm.882619.
Most studies of the skin and how it responds to local heat have been conducted with either water, thermodes, or dry heat packs. Very little has been accomplished to look at the interaction between air humidity and temperature on skin temperature and blood flow. With variable air temperatures and humidity's around the world, this, in many ways, is a more realistic assessment of environmental impact than previous water bath studies.
MATERIAL/METHODS: Eight young and 8 older subjects were examined in an extensive series of experiments where on different days, air temperature was 38, 40, or 42°C. and at each temperature, humidity was either 0%, 25%, 50%, 75%, or 100% humidity. Over a 20 minute period of exposure, the response of the skin in terms of its temperature and blood flow was assessed.
For both younger and older subjects, for air temperatures of 38 and 40°C., the humidity of the air had no effect on the blood flow response of the skin, while skin temperature at the highest humidity was elevated slightly. However, for air temperatures of 42°C., at 100% humidity, there was a significant elevation in skin blood flow and skin temperature above the other four air humidity's (p<0.05). In older subjects, the blood flow response was less and the skin temperature was much higher than younger individuals for air at 42°C. and 100% humidity (p<0.05).
Thus, in older subjects, warm humid air caused a greater rise in skin temperature with less protective effect of blood flow to protect the skin from overheating than is found in younger subjects.
大多数关于皮肤及其对局部热反应的研究都是用水、热模或干热袋进行的。很少有研究关注空气湿度和温度对皮肤温度和血流的相互作用。由于世界各地的空气温度和湿度都在变化，这在很多方面比以前的水浴研究更能真实地评估环境影响。
材料/方法：在一系列广泛的实验中，检查了 8 名年轻和 8 名年长的受试者，在不同的日子里，空气温度分别为 38、40 或 42°C，在每个温度下，湿度分别为 0%、25%、50%、75%或 100%。在 20 分钟的暴露期间，评估了皮肤在温度和血流方面的反应。
对于年轻和年长的受试者，在空气温度为 38 和 40°C 时，空气湿度对皮肤血流反应没有影响，而在最高湿度下皮肤温度略有升高。然而，在空气温度为 42°C 时，在 100%湿度下，皮肤血流和皮肤温度显著升高，高于其他四种空气湿度（p<0.05）。在年长的受试者中，血液流量反应较小，皮肤温度比年轻受试者在空气温度为 42°C 和 100%湿度时高得多（p<0.05）。
因此，在年长的受试者中，温暖潮湿的空气会导致皮肤温度升高更大，而血流的保护作用较小，无法保护皮肤免受过热。
