Most people know that radioactive energy can be harnessed to provide electricity and even to diagnose and treat certain illnesses. But would it surprise you to learn that radioactive materials also perform an important safety function by lighting emergency EXIT signs?
Look for the EXIT sign the next time you go to work, school, a sporting event, religious service, the movies, or the mall. If the sign glows green or red, chances are it contains a radioactive gas called tritium. The tritium, a radioactive isotope of hydrogen, is sealed into glass tubes lined with a chemical that glows in the dark. Tritium emits low-energy radiation that cannot penetrate paper or clothing and even if inhaled, it leaves the body relatively quickly. As long as the tubes remain sealed, the signs pose no health, safety, or security hazard.
NRC estimates there are more than 2 million of these signs in use in the United States. To ensure safety in handling and the manufacturing process, NRC and its Agreement State partners regulate the manufacture and distribution of tritium EXIT signs. Companies have to apply for and receive a license before they can manufacture or distribute one of these signs.
But because the signs are designed to be inherently safe, NRC does not require any special training before a building can display the signs. Users are responsible for meeting the requirements for handling and disposal of unwanted or damaged signs and for reporting any changes affecting the signs.
Proper handling and disposal is the most important safety requirement for these signs. A damaged sign could contaminate the immediate area and require an expensive cleanup. That is why broken or unwanted signs must be return to a licensed manufacturer, distributer, radioactive waste broker or radioactive waste disposal facility.
Tritium EXIT signs are one of several types of radioactive consumer products that NRC allows. These products can be produced and sold ONLY if they have a benefit that outweighs any radiation risk. See our earlier blog post for more information on how we regulate these products.Maureen Conley Public Affairs Officer