Photoluminescent exit signs work by absorbing and storing available ambient light, then in darkness they release this stored light in the form of a bright luminous glow. The UL924 standard requires exit signs to be legible for a minimum of 90 minutes at the maximum listed viewing distance of each sign. An exit sign that has a UL924 listing has met the highest building code available. ExitGlo™ UL924 listed exit signs not only meet, but exceed this specification.
Check out our Eco-Friendly Exit Signs at this link, Photoluminescent Exit Signs