Temperature is one of the most closely regulated of body parameters. Relatively small variations in core temperature can be life threatening. For instance, a high fever represents an increase of just a few degrees Celsius over the normal core temperature. The regulation of body temperature occurs in response to a changing thermal environment. There are a number of key parameters in the environment which influence the amount of thermal stress that the body experiences.
People differ in their response to thermal stress.
Sometimes it is useful to assess people's subjective responses to the thermal environment, i.e., how warm or cold it feels to them. After all, if workers feel cold, then this may present a problem, even if objective measures seem to indicate that the environment should be comfortable. Different scales for subjective assessment of the environment have been developed. The following table shows two of these scales and the way in which they are related. The heat balance equation noted earlier shows that heat exchange is due to a number of factors.