Excessive condensation, corrosion, and mildew typically occur when relative humidity exceeds what percentage?

Excessive condensation, corrosion, and mildew issues are commonly associated with high relative humidity levels. When relative humidity rises above 60%, it creates an environment conducive to these problems. At this level, the air holds a significant amount of moisture, and as air temperature fluctuates or surfaces cool, condensation occurs more readily. This excess moisture can lead to corrosion of materials, especially metals, and promote the growth of mildew and mold, which can not only damage property but also pose health risks to occupants.

Humidity levels greater than 60% are often recognized as a threshold for indoor spaces where proper ventilation and moisture control become crucial to maintaining a healthy indoor environment. This is consistent with guidelines from public health organizations that emphasize keeping indoor humidity levels below this percentage to prevent such issues.

While other options indicate different humidity levels, they either fail to recognize the critical threshold for these problems or are too high for general indoor environments, leading to increased risk without addressing the fundamental issues that arise under excessive moisture conditions.