Could grandfather's war watch turn out to be poisonous?

GETTING TO THE HEART OF MEDICAL MATTERS

- Dr Rosemary Leonard

Q I inherited a watch from my grandfather that was issued to him when he was serving in the war. The numbers and the dial are luminous, and I've read that this could mean they are emitting radon. Just how dangerous is this? I only wear the watch occasionally.

In the first half of the 20th century, paint containing radium was used in watches as this gave luminescence to the hands and dials. They were issued to servicemen as they could be useful for seeing the time in the dark.

However, radium is radioactive and produces radon gas, and exposure to this can increase the risk of developing cancer, especially of the lungs. The way you can test to see if it is emitting radon is with a Geiger counter - a specialist in old watches may be able to help you with this.

A study found that 30 radium dial watches, kept in a small bedroom, produced radon levels of 134 times the maximum safe level, and old watch collectors should certainly be aware of this. The risk from an individual watch is low, especially if you only wear it occasionally, but will be greater if the dial is cracked.

Check the condition of your grandfather's watch, don't tamper with the glass (so it stays sealed) and make sure you keep it in a well ventilated space.