How does humidity affect human comfort levels?

High humidity significantly impacts how humans perceive temperature and comfort levels. When humidity levels are high, the amount of moisture in the air reduces the body's ability to cool itself through the evaporation of sweat. This results in an increased sensation of heat, making people feel warmer than the actual temperature indicates. This effect is often quantified using the Heat Index, which combines air temperature and relative humidity to provide a more accurate representation of perceived temperature.

In contrast, low humidity can lead to discomfort as well, but its effects do not contribute to an overall sensation of warmth in the same way high humidity does. Additionally, humidity is a crucial factor in indoor air quality, but it does not solely determine it. Therefore, understanding how high humidity affects the thermal comfort of individuals is essential, as it plays a significant role in residential and commercial HVAC system design and operation.