What percentage should the humidity be in the CDC?

• A. 10-20%
• B. 20-40%
• C. 30-50%
• D. 60-80%

Answer: (C)

Keeping humidity in a moderate range helps reduce health and safety risks in facilities like the CDC. Relative humidity around 30-50% provides enough moisture to prevent dry air and static buildup, which can irritate skin and cause static discharge around equipment, while staying low enough to avoid condensation, mold growth, and moisture-related corrosion. This balance also tends to limit the survival of many airborne pathogens compared with either very dry or very humid air. That’s why thirty to fifty percent is the commonly preferred target. Humidity much lower (10-20%) is too dry and can cause static and discomfort; humidity much higher (60-80%) promotes mold, condensation, and microbial growth.