All electronics including televisions have recommended temperature and humidity ranges for two conditions: operations and storage. Use of any electronics in temperature or humidity ranges outside these recommendations can cause temporary or permanent damage to the set.
Operating and Storage Humidity
Your television will list its operating and storage humidity ranges in the manual that came with the set, or on the manufacturer's Web page under the entry "technical specifications." Operating humidity is the range of humidities in which the television can be used, while storage humidity is the range for long-term storage when the television is not in use. Electronics for mass consumption are designed to operate safely and/or be stored in temperature and humidity ranges where most people would be comfortable.
The danger from high humidity comes from condensation. Condensation is when moisture collects as a liquid on a surface adjacent to humid air; this is why the outside of a glass of cold water becomes wet on a hot summer day. All electronics generate heat inside their cabinets when they're in use, and when they're in storage, their cases can cause differences in air temperature inside and outside the television. Humidity is generally not dangerous to televisions while moisture remains in the air, but any condition causing condensation can cause electrical shorts or other damage to electronic components.
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The same methods used to control humidity for human being apply to electronics. Air conditioning units or dehumidifiers can be used to remove moisture from the air, making humid environments more comfortable for people and televisions alike. However, if you are in a room where sweat is forming on your skin and not drying off, that indicates air that is too humid for you to be comfortable, and may be too high for the safe operation of your electronics.
Resolving Humidity Issues
If your television display or other components have problems that you think may be caused by humidity, turn the television off immediately. Move the television to the driest environment you can find, or turn on an air conditioner or dehumidifier in the immediate area. Most televisions have humidity storage ranges as high as 95 percent, so simply leaving the television off until the air is drier may allow it to safely operate later. However, if the television shows persistent display problems after being exposed to high humidity, contact the manufacturer to determine whether you need a repair.