Ambient relative humidity levels between 45 percent and 50 percent are the most suitable for server operation in order to:
Provide an operating time buffer in the event of environmental control system failure
Help avoid failures caused by the intermittent interference from static discharges that occur when relative humidity is too low
Electrostatic discharge (ESD) is easily generated and less easily dissipated in areas where the relative humidity level is below 35 percent. ESD risk becomes critical when levels drop below 30 percent.