Is that exit sign radioactive?

Adorning the exits of the church building I attend are exit signs that look generally unassuming like this:

However, you may note that there are no wires or conduit leaving this lighted sign. How is it lighting up then? It turns out if you look underneath the sign, you see a label that looks like the picture below. It is radioactive!

But, don't worry, this exit sign is not the reason you feel warm and fuzzy when you leave the building. In fact, the sign is designed so that no radiation should leave the tubes holding the radioactive material, tritium. Tritium emits one kind of radioactive particle, beta particles, which are contained within the tubes that hold the tritium, and nothing else. The insides of these tubes are lined with a phosphorescent material. When the radioactive particles collide with the phosphor, green light is emitted!

This type of sign is only good for a about 10-15 years. During that time, no electricity is required, and everything will be fine as long as no one knocks the sign off and it crashed down and releases all the radioactive tritium gas.