De-Mystifying the Self Luminous Exit Sign

A lot of people are concerned about the dangers of radiation and its long term effects on the planet. Incidents like the Fukushima Disaster and Chernobyl have done little to ease our collective fear of that tri-fin radiation symbol. Tritium, the radioactive glowing component in self luminous exit signs, is actually found in trace amounts all over the earth. In fact it is only 1 electron away from being the hydrogen atom found in tap water. That's right, you're probably drinking tritium right now.


Tritium powered exit signs saw their heyday between the 1950s and 1970s. At the time photoluminescent signs did not exist, so the only non-electrical exit sign alternative were "self-illuminating" (read: nuclear). The winds of change in environmental controls and the Cold War did little to raise the declining popularity of self luminous signs.

The Truth About Tritium

Known scientifically as 3-H or H3 (hydrogen-3), tritium gas is a radioactive isotope of hydrogen. It has a nucleus that contains one proton and two neutrons, compared to the most common hydrogen isotope, protium, which has no neutrons.

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Tritium occurs in nature when cosmic rays interact with atmospheric gases. Tritium is produced as a byproduct of nuclear reactors and is used in exit signs and other self-illuminating devices. When contained inside sealed glass tubes, the gas is completely safe for humans. It only becomes harmful when inhaled or ingested via food or water, which can only happen if the tubes are broken.

So far there has never been a single incident of tritium poisoning from installed signs. However, improperly disposed signs can pose a threat when tossed in a normal landfill. En masse, a large enough amount of tritium could contaminate the water table to raise the acceptable levels in nearby drinking water.

Phosphor Explained

Tritium does not glow on its own, but acts as the "battery" that charges phosphor, the glowing component in these signs. Phosphor is  rare earth compound that comes from meteors and volcanoes. When combined with radioactive gas, it creates a neon green glow. Phosphor is widely used in the monochrome computers of the 1980s. 

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Disposal and Replacement in One

Here at the Self Luminous Exit Sign company, we'll find you the safest and most reliable signs out there. The number of self luminous vendors has gone down in recent years while the demand for these all-weather, non-electrical wonders continues. We'll get you in the queue quickly so you'll get your sign lickety-split. Call 800.379.1129 today!

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