Gaseous Tritium Lights

[demographic]

As least it’s not on their helmets!

Luminescent plankton is quite bright when there are no artificial light sources.
Not sure how effective it would be for a light source on land but an interesting concept. I could see working it as a marker.

Doubt it, the the beta particles it emits are very low energy and are stopped by about 6mm of air so the container the tritium is in will stop them.
Also as its such low energy it won't create gama rays via the bremsstrahlung effect.

 

[Tengu]

Unlikley. At least I havent ever heard of it.

(But Beta lights are the coolest thing ever, IMHO).