Jump to main content.

Discarded Tritium Exit Signs

RadTown USA Topics
  Use of Radioactive Materials:
Printer Friendly Version
Tritium Exit Signs (PDF)
(2pp, 147Kb)
[about pdf format]

This page provides information on tritium exit signs, including proper handling and disposal methods.

On this page:


Exit signs are mounted in almost every building we go into, like high schools, grocery stores, movie theaters and shopping malls. Many exit signs contain tritium, the radioactive form of hydrogen. Mixing tritium with a chemical that emits light in the presence of radiation, known as "phosphor in a tube" (a sealed source), creates a continuous, self-powered light source. This useful property of tritium can be applied to situations where a dim light is needed but where using batteries or electricity is not possible.

Using tritium in exit signs ensures that the sign will remain illuminated in the event of an electrical outage or a fire. If the tubes in the exit signs are severely damaged, the tritium, which exists in the sign as a high temperature gas, might escape into the local area but most likely will quickly disperse in the air. Because a damaged exit sign will have relatively high levels of tritium in it, you should not handle it.

Do not handle damaged tritium signs.

While damage to tritium exit signs is rare, it is most likely to occur when a sign is dropped during installation or smashed in the demolition of a building. If not damaged during demolition, tritium exit signs can be broken when they are illegally dumped in community landfills.

Tritium is naturally produced by the interaction of cosmic rays with the atmosphere. Tritium can also be produced by man-made processes, as is the case of tritium exit signs. Tritium decays by emitting a low-energy beta particle that cannot penetrate the outer layer of human skin. Therefore, the main hazard associated with tritium is internal exposure by inhalation. 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. Some types of radioactive materials stay in the body and are deposited in different body organs. Other types are eliminated in blood, sweat, urine, and feces.

As with all ionizing radiation, exposure to tritium increases the risk of developing cancer. However, tritium exposure is likely to have a limited biological impact because it emits very weak radiation and leaves the body relatively quickly. Because of tritium’s short biological half-life, tritium must be ingested in rather large amounts to pose a significant health risk.

Top of page

Who is protecting you

U.S. Environmental Protection Agency(EPA)

Under the Clean Air Act, EPA establishes regulatory requirements for hazardous air pollutants including tritium air releases. Under the Safe Water Drinking Act, EPA sets limits for acceptable levels of tritium in drinking water. EPA also responds to emergencies involving tritium releases to the environment. In addition, before being approved for public use, sites previously contaminated with tritium must meet EPA's risk-based criteria for soil and ground water.

U.S. Department of Labor (DOL)

DOL's Occupational Safety and Health Administration issues regulations and standards for the safety of workers in a wide range of occupational settings including construction and demolition.

U.S. Nuclear Regulatory Commission(NRC)

The primary mission of NRC is to protect public health and safety and the environment from the effects of radiation from nuclear reactors, sealed sources containing radioactive materials, and radioactive waste facilities.

The States

Each state has one or more programs to address radiation protection issues and respond to and investigate incidents involving tritium.

Thirty-four states have signed formal agreements with NRC, providing the states regulatory responsibility over small quantities of special nuclear material and its source and byproducts. These states are known as NRC-Agreement States.

Top of page

What you can do to protect yourself

Some basic precautions can minimize the risks. The tritium in exit signs can be identified by the tube (sealed source) that contains tritium. In an exit sign, the tubes are used to spell out the word “EXIT.”

Disposal of the broken sign should be arranged through the manufacturer or a health physics consultant. When an exit sign containing tritium is damaged and the sealed tube within the sign is broken, you should:

Top of page


March 30, 2012. U.S. Environmental Protection Agency
On this page, you can find basic information about the radioactive element tritium.
Ask the Experts: Cleanup of broken tritium sign exit EPA
March 30, 2012. Health Physics Society
Here you can learn how to clean up broken exit signs.
Directory of Agreement State and Non-Agreement State Directors and State Liaison Officers
March 30, 2012. U.S. Nuclear Regulatory Commission
This page provides a list of Nuclear Regulatory Commission Agreement State contacts.
Safety and Health Topics: Ionizing Radiation
March 30, 2012. U.S. Department of Labor, Occupational Safety & Health Administration
On this page, you can find information about worker health and safety standards for those working with or around ionizing radiation sources. Links to additional information are listed on this page.
Self-Powered Radioactive Exit Signs (PDF) [about pdf format] exit EPA
March 30, 2012. Harvard University Environmental Health and Safety
This page provides general information on what tritium exit signs are, how to handle them and how to dispose of them properly.
Radioactive Solid Waste Reports exit EPA
March 30, 2012. Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection
This site contains links to fact sheets about tritium and exit sign owner responsibilities. It also links to reports on radionuclides in Pennsylvania landfills.

Top of page


Local Navigation

Jump to main content.