In this months BHI mag (November 2018) is an article “Radon Hazards of Luminous Timepieces” Understanding Risks From vintage watches.
Luminous timepieces really took off during the Great War, when a wristwatch with a luminous dial quickly became regarded as a necessity. The hazards of radium paint were highlighted by the story of the “Radium Girls”, luminous dial painters of the 1920s not only shaped their brushes with their lips ,but painted their teeth, lips and eyebrows with luminous radium paint, consuming significant amounts of radium. When Radium enters the body it results in cancers and many died from this.
The problem for us watch repairers is detecting if the vintage watch you are repairing/servicing has a radium dial or hands is not easy. Radio-luminescent paint ceases to glow after a few years, so lack of glow from the paint is not a reliable indication of whether it is radioactive or not. The only way to be 100% sure is to use a radiation detector.
Conclusion
Radiation and radon gas from radio - luminescent paint a potentially dangerous to watch collectors and repairers. Open storage in living or working areas that contain potential Radio-luminescent paint should be avoided. For those who regularly work on vintage watches should invest in a radon detector. If not sure use a mask when disassembling and store the dials and hands under cover and wear finger cots when handling.