Originally Posted by
JohnBurke
Inside an aircraft instrument, it's just not an issue at all. None.
As long as it stays there. If it gets out (like the one I took apart as a kid) and into your body the long half-life means it will keep slow-cooking whatever tissue it absorbs into for the rest of your life.
It's mostly alpha radiation, so correct that it won't emit out of a closed instrument, or penetrate skin (the problem is if the radium compound gets inside you).