When people hear the word "radioactive," they often think of nuclear explosions or science fiction mutations. But radioactivity—especially in the case of tritium—is much more common and helpful than many realize. In fact, tritium is used safely in medical imaging, scientific research, and one important area you see every day: emergency exit signage.
Next time you’re in a movie theater, retail store, school hallway, or stadium and look up near an exit, take a closer look at the EXIT sign. If the letters glow steadily without flickering or dimming—and there are no wires or batteries—it’s likely a Green Tritium Exit Sign.
What Is a Tritium Exit Sign?
Tritium exit signs, also called self-luminous exit signs, contain small amounts of tritium gas—an isotope of hydrogen—sealed inside phosphor-coated glass tubes. As the gas decays naturally, it emits low-energy beta radiation, which causes the phosphor to glow. The result: a bright, always-on sign that requires no electricity, batteries, or maintenance.
Because the radiation is so low-energy, these signs are completely safe under normal use as long as the tubes remain intact and sealed. They're approved by the U.S. Nuclear Regulatory Commission (NRC) and have been used safely in thousands of commercial and industrial facilities.
Do Tritium Exit Signs Expire?
Yes. Tritium has a natural half-life of about 12.3 years, meaning the glow will gradually fade over time. Most tritium signs are rated for 10, 15, or 20 years of visibility. After that, the sign will no longer be visible at the required distance and must be replaced.
Why Does Tritium Fade?
Tritium is a radioactive isotope with a half-life of 12.3 years. As it decays, it emits beta particles that excite the phosphor coating in the glass tubes to produce light. Over time, as the tritium gas is consumed through radioactive decay, the number of beta emissions decreases—causing the glow to gradually dim. After two decades, only about 25% of the original brightness remains.
Where Are Tritium Signs Used?
Tritium exit signs are ideal in environments where electricity is unavailable or unreliable. Common locations include:
- Underground tunnels and mines
- Elevator shafts and stairwells
- Cold storage facilities
- Outdoor stadiums and arenas
- Oil rigs and marine applications
- Remote outbuildings and unpowered shelters
- No Power Exit Signs applications
Green vs. Red vs. Black Tritium Signs
Choosing the right color tritium sign depends on your local code, lighting conditions, and aesthetic preference:
- Green Tritium Exit Sign: The most common choice in North America. Green is highly visible in smoke and darkness, and it meets UL 924 standards.
- Red Tritium Exit Sign: Required in some local codes (e.g., New York City) and preferred in applications where green lighting may be confusing or blend with background lighting.
Disposing of Expired Tritium Signs
Because tritium is a regulated radioactive material, it must be recycled—not thrown away. The NRC requires proper documentation and handling of expired units to avoid accidental exposure, especially if the glass tubes are cracked or broken.
We offer a streamlined Tritium Exit Sign Recycle service. Whether you're replacing an old sign or disposing of one that’s reached its expiration, we make it easy to return your old unit for compliant, environmentally responsible recycling.
Why Tritium Is a Smart Emergency Lighting Option
- Completely self-powered – no wires or batteries
- UL 924 compliant and always on
- Safe, sealed, and maintenance-free
- Ideal for No Power Exit Signs and Glow-In the Dark Exit Signs alternatives
- Works in wet, remote, and power-inaccessible locations
Final Thoughts
So, is tritium dangerous? Not when used properly. In fact, it’s one of the safest and most reliable forms of emergency egress lighting available. With zero maintenance, a sleek design, and reliable glow in the darkest conditions, Tritium Exit Signs are a smart choice for any facility looking for dependable, non-electric signage. Just don’t forget—when it’s time to replace them, recycle responsibly. It’s safe, simple, and legally required.