What is the relative humidity inside the International Space Station?

The relative humidity inside the International Space Station (ISS) is typically maintained between 40% and 60%. This level is carefully controlled to ensure the comfort of the astronauts, prevent equipment corrosion, and reduce the risk of mold and bacteria growth. The environmental systems on the ISS work to balance humidity levels, as the absence of natural atmospheric circulation in microgravity can lead to fluctuations.