Tritium in Exit Signs

Radiation Facts

Using tritium in exit signs allows the sign to remain lit if the power goes out.
Tritium is a radioactive isotope that needs special handling procedures.
Tritium is most dangerous when it is inhaled or swallowed.

Many exit signs contain tritium. Tritium is a naturally-occurring radioactive isotope of hydrogen that is often used to light up a sign without batteries or electricity. Tritium exit signs will glow without electricity or batteries for more than 10 years. This is beneficial in areas where it is difficult to install electric signs (like above doors) and in emergency situations when power is lost.

On this page:

About Tritium in Exit Signs
What you can do
Where to learn more

About Tritium in Exit Signs

Tritium is the radioactive form or of hydrogen. It exists as a gas or as a liquid when combined with oxygen to form tritiated water. Tritium can be naturally produced or man-made.

Image of a lit tritium exit sign. — Tritium exit signs glow in the dark, even when the power is out.

When mixed with certain chemicals, tritium becomes a continuous, self-powered light source. This phenomena, called , occurs when radioactive particles from tritium decay and hit a small bit of material called a phosphor, making it fluoresce or emit light. Tritium exit signs are marked with a permanent warning label. Tritium exit signs are useful because they do not require a traditional power source such as batteries or hardwired electricity. This means that tritium exit signs will remain lit if the power goes out. Additionally, tritium exit signs do not require a cord or additional power source, so they can be mounted in locations where traditional power sources do not exist.

No radiation is emitted from a working, unbroken, tritium exit sign. Tritium gas is typically contained in small glass vials, so damage to tritium exit signs is most likely to occur when a sign is dropped during installation or smashed in the demolition of a building. If a tritium exit sign is damaged, the tritium could be released.

Tritium emits beta particles. Beta particles can be stopped by a layer of clothing or by a thin layer of aluminum. Beta particles are most harmful when inhaled or swallowed. Internal contamination occurs when people swallow or breathe in radioactive materials, or when radioactive materials enter the body through an open wound or are absorbed through the skin. Learn the radiation basics.

If a tritium exit sign is broken, never tamper with it. Leave the area immediately and call for help. At school, you should report the damaged sign to a teacher, janitor or someone in the main office. In other buildings, you can report the problem to a security guard. Tritium must be inhaled or ingested in large amounts to pose a significant health risk.

Unwanted tritium exit signs may not be put into ordinary trash; they require special disposal. Tritium exit signs that are illegally put in ordinary landfills can break and contaminate the site. Owners of buildings are responsible for ensuring the safe operation and disposal of tritium exit signs.

What You Can Do

Educate yourself. Learn to recognize tritium exit signs from battery or electronically powered exit signs. Tritium exit signs spell out the word “EXIT” in green or red glowing light when the lights are out. They should be labeled as having tritium inside. Also, learn to recognize a damaged tritium exit sign. All four letters in “EXIT” should be lit. If a letter or part of a letter is not lit, the sign may be damaged. Leave the area around a damaged tritium exit sign immediately.
Do not tamper with tritium exit signs. Never tamper with a tritium exit sign. Only trained professionals should handle damaged tritium exit signs.
Report damage. Report damaged tritium exit signs. At school, you should report the damaged sign to a teacher, janitor or someone in the main office. In other buildings, you can report the problem to a security guard. For additional information, contact your state radiation protection control program.

Where to Learn More

The U.S. Nuclear Regulatory Commission (NRC)

Manufacturers and distributors of tritium exit signs must receive a radioactive materials license. Facilities that use tritium exit signs must put one person in charge of making sure that regulations are followed. Most states have signed formal agreements with the NRC, providing the states regulatory responsibility over small quantities of special nuclear material. These states are known as Agreement States. The radioactive materials license can be issued either by the NRC or the appropriate Agreement State.

Directory of Agreement State and Non-Agreement State Directors and State Liaison Officers
This webpage provides a list of the NRC Agreement and Non-Agreement State contacts.

Fact sheet on Tritium EXIT Signs
This webpage contains information on tritium, tritium exit signs and the rules for using tritium to make signs and describes how they should be disposed.

The U.S. Department of Labor (DOL), Occupational Safety and Health Administration (OSHA)

OSHA makes rules and standards to keep workers safe from radiation in workplace settings. There are special rules and procedures that must be followed when a worker is handling radioactive materials. OSHA is responsible for providing these guidelines and appropriate training to keep workers safe. When an accident occurs, OSHA must be notified and may investigate the cause of the workplace accident.

Occupational Safety for Radiation Workers
This website provides information about radiation sources in the workplace and about worker rights to a safe workplace environment.

OSHA Standards for Ionizing Radiation
This webpage provides information on OSHA standards protecting workers from ionizing radiation.

The States

Each state has a radiation safety program, and often a radiation safety officer, that will respond to and investigate incidents involving release of tritium and other radionuclides.

State Radiation Protection Programs
The Conference of Radiation Control Program Directors (CRCPD)
This webpage opens to a map providing links and contact information for each state's Radiation Control Program office.

Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection

Facts about Radioactive Tritium
This fact sheet contains detailed information about tritium exit sign owner responsibilities.

The U.S. Environmental Protection Agency (EPA)

The EPA uses its authority from the Clean Air Act and Safe Drinking Water Act to set limits on the amount of radioactive material released into the air and water from radioactive sources. The EPA also plays an important role in cleaning up some of the nations most contaminated hazardous waste sites.

Radionuclide Basics: Tritium
This webpage provides basic information about tritium.

The U.S. Department of Energy (DOE), Los Alamos National Laboratory

Los Alamos National Laboratory enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

Self-Luminous Exit Signs (PDF) (620.86 K)
This fact sheet provides important information about tritium exit signs and their disposal.