Editing Humidity (section)

=== Electronics ===
[[File:Silica gel - bag.jpg|thumb|upright|[[Desiccant]] bag ([[silica gel]]), commonly included in packages containing electronic products to control humidity]]

Electronic devices are often rated to operate only under certain humidity conditions (e.g., 10% to 90%). The optimal humidity for electronic devices is 30% to 65%. At the top end of the range, moisture may increase the conductivity of permeable [[Insulator (electrical)|insulators]] leading to malfunction. Too low humidity may make materials brittle. A particular danger to electronic items, regardless of the stated operating humidity range, is [[condensation]]. When an electronic item is moved from a cold place (e.g., garage, car, shed, air conditioned space in the tropics) to a warm humid place (house, outside tropics), condensation may coat circuit boards and other insulators, leading to [[short circuit]] inside the equipment. Such short circuits may cause substantial permanent damage if the equipment is powered on before the condensation has [[evaporated]]. A similar condensation effect can often be observed when a person wearing glasses comes in from the cold (i.e. the glasses become foggy).<ref>{{cite web|title=Fogging Glasses|url=http://www.newton.dep.anl.gov/askasci/gen01/gen01333.htm|access-date=2012-08-08|archive-date=2015-02-26|archive-url=https://web.archive.org/web/20150226032245/http://www.newton.dep.anl.gov/askasci/gen01/gen01333.htm|url-status=dead}}</ref> 

It is advisable to allow electronic equipment to acclimatise for several hours, after being brought in from the cold, before powering on. Some electronic devices can detect such a change and indicate, when plugged in and usually with a small droplet symbol, that they cannot be used until the risk from condensation has passed. In situations where time is critical, increasing air flow through the device's internals, such as removing the side panel from a PC case and directing a fan to blow into the case, will reduce significantly the time needed to acclimatise to the new environment.

In contrast, a very low humidity level favors the build-up of [[static electricity]], which may result in spontaneous shutdown of computers when discharges occur. Apart from spurious erratic function, electrostatic discharges can cause dielectric breakdown in [[solid-state device]]s, resulting in irreversible damage. [[Data center]]s often monitor relative humidity levels for these reasons.