How Much Radiation Does a TV Emit?
By John Papiewski
Color television sets made before the 1970s put out a small amount of X-ray radiation, generated by the high voltages inside the equipment. Although hazardous, it is not the type of radiation associated with radioactive materials -- the TV won't make you glow in the dark. Modern flat-screen TVs don't use high voltages, although some have components that produce ultraviolet radiation. TV makers have taken steps to prevent this radiation from reaching the viewer.
X-rays are typically produced when electrons at between 20,000 and 100,000 volts hit a metal target; the higher the voltage, the more harmful the X-rays become. Prolonged exposure to X-rays causes damage to living tissues and the fragile biological molecules inside them, possibly leading to radiation burns, cancer and other harmful effects. Although X-rays are highly useful in medical and industrial settings, using them safely involves careful radiation monitoring and the use of lead aprons and other protective gear.
Ultraviolet radiation, an invisible form of light having wavelengths shorter than the color violet, is less harmful than X-rays, but can still harm living things. The sun produces abundant amounts of ultraviolet light, but the ozone layer in the Earth's upper atmosphere blocks it. Black lights are harmless, long-wave forms of ultraviolet light; other artificial sources, such as germicidal lamps used in hospitals produce more energetic, short-wave UV which can cause skin burns and blindness.
Older televisions form images in a large glass screen called a picture tube or cathode ray tube. The CRT works by producing a high voltage electrical current that makes a phosphor coating glow. Color TVs produce voltages between 20,000 and 40,000 volts and consequently are a potential source of weak X-ray radiation. The X-rays become a slight hazard if you sit very close to the screen. In the 1970s, TV manufacturers added lead to the picture tube glass, significantly reducing the radiation and removing the hazard.
The Liquid Crystal Displays used in some flat-screen televisions do not create light directly, but require a white backlight which the LCD then filters, producing an image. Some TVs use a fluorescent lamp as the backlight; fluorescent lamps produce some UV which the manufacturer removes with specially-treated glass. As a side benefit, the ultraviolet-free light gives the LCD display a longer operating life. Plasma TVs do not use fluorescent light and don't pose a UV risk; TVs that use light-emitting diode backlights also do not generate UV.
Chicago native John Papiewski has a physics degree and has been writing since 1991. He has contributed to "Foresight Update," a nanotechnology newsletter from the Foresight Institute. He also contributed to the book, "Nanotechnology: Molecular Speculations on Global Abundance."