Originally Posted by
rickair7777
Radium has a very long half-life relative to human life-spans... practically speaking any radium device will be just as radioactive as the day it was manufactured. I would be careful possessing or handling such antiques...
If the paint deteriorates (if the inherent chemistry doesn't do that, the radiation likely will), the dust could be hazardous. Although the risk is probably pretty low compared to being a professional radium paint licker.
Tritium (commonly used today) has a much shorter half-life, about a decade.
Inside an aircraft instrument, it's just not an issue at all. None.