Humidity plays a significant role in indoor air quality. When humidity levels are too high, it can promote the growth of mold and dust mites, which negatively impact air quality and cause health issues such as allergies and respiratory problems. On the other hand, if the humidity is too low, it can lead to dry skin, irritation of the respiratory tract, and increased levels of airborne dust. Maintaining an optimal humidity level between 30% and 50% can help improve indoor air quality and comfort.