What is the typical human comfort range in relative humidity (RH)?

The typical human comfort range in relative humidity is indeed best represented by the range of 40-60%. This range is regarded as optimal because it helps to balance moisture in the air, which is vital for maintaining comfortable indoor conditions.

At 40-60% relative humidity, people generally experience reduced instances of dry skin, irritation in the respiratory tract, and other discomforts often caused by dry air. Additionally, this humidity range helps to minimize the growth of mold, mildew, and dust mites, which can flourish in higher humidity, potentially leading to adverse health effects and discomfort.

A relative humidity below 30% can lead to dry air sensations and health issues like dry throat and nasal passages, while values over 60% can increase the potential for mold growth and may also make the space feel warmer than it actually is, contributing to discomfort. Thus, the 40-60% range is recognized as the sweet spot for human comfort indoors.