High relative humidity (above 80%) creates a serious risk for corrosion of electronic contacts, printed circuit boards (PCBs), and metallic components. Moisture in the air condenses more easily, especially when surfaces are cooler than ambient dew point. This can lead to oxidation of connectors, degradation of solder joints, and eventual failures in ICT hardware.
Electrostatic discharge (ESD) risks, by contrast, increase at low humidity (below 30%) because dry air promotes charge buildup. Therefore, option C is incorrect here. Similarly, option D (cooling risk from wet-bulb temperature) applies to evaporative cooling efficiency, not directly to ICT risk.
ASHRAE recommends data centers maintain RH between 40–60% for optimal reliability. Values above 80% RH are considered outside the recommended operating envelope and significantly increase the risk of corrosion, especially in the presence of airborne contaminants like sulfur dioxide (SO₂) or hydrogen sulfide (H₂S).
Therefore, the verified risk at 85% RH is corrosion-related degradation.
[References: ASHRAE TC 9.9 Thermal Guidelines (2016 Edition, Table 4.1), IEC 60721-3-3 Environmental Conditions for ICT Equipment., , ]
