Humidity

Humidity is the amount of water vapour in air. Levels are usually quoted as relative humidity, which is the ratio between the actual amount of water vapour in the air and the maximum amount of water vapour that the air can hold at that air temperature

High relative humidity (>80%) starts to prevent evaporation of sweat from the body. This evaporation is a major way of regulating body temperature. Therefore, high humidity can contribute to heat exhaustion and heat stroke.

Humidity is particularly a concern when people are required to wear extra clothing (i.e. in the form of personal protective equipment PPE). In this case the humidity inside clothing can be significantly higher than outside.

Humidity is covered by the Workplace (Health, Safety and Welfare) Regulations 1992.