The Heat Index (HI) is an index that combines air temperature and relative humidity in an attempt to determine the human-perceived equivalent temperature. The Heat Stress Index is defined as the relation of the amount of evaporation required as related to the maximum ability of the average person to evaporate fluids from the body in order to cool themselves. When the Heat Stress Index is high which can lead to particularly dangerous conditions, can actually die from being too warm and unable to cool themselves properly. (Refer to the Heat Stress)
Reference Definition by Ncdc.noaa.gov: A Heat Stress Index means when both temperature and humidity are high, humans can experience considerable heat stress. The combined effects of temperature and humidity cannot be directly measured but can be assessed by calculation of an “apparent temperature” (A). Ignoring wind effects, one can estimate apparent temperature as A (°C) = -1.3 + 0.92T + 2.2e, where T is ambient air temperature (°C) and e is water vapour pressure (kPa) (Steadman 1984). This index of “how hot it feels” should not be confused with the Heat Index used by NOAA’s National Weather Service.
Related Definitions in the Project: The Construction; HSE Management
