This piece has been updated to include advise on what do do if you have a device in your possession.
It’s not uncommon for history buffs to collect artefacts from the second world war, but a new study from the Universities of Northampton and Kingston highlights a hidden risk which could very well prove deadly. Paints used to make dials glow in the dark are known to emit colourless, odourless radon gas, but this is the first time a figure has been put on the risk involved – and it’s pretty high.
The 30 antique watches used in the study cumulatively provided concentrations of radon 134 times greater than the recommended safe level when kept in a typical 2.5 x 7.7-metre unventilated box-room. The worse the condition of the items, the higher the risk, with three of them in such a state that they emitted concentrations well above the level at which Public Health England (PHE) recommends remediation.
While the study highlights the risk of a poorly-ventilated box-room, of the kind where collectors may keep their prized possessions, the researchers were keen to highlight that the radon level is so high that entire houses could be at risk.
“These results show that the radon emitted from individual watches can potentially pose a serious cancer risk,” said Dr Robin Crockett, a co-author of the study. This is particularly cruel when you consider that it’s not just collectors, but servicemen and their families who keep the watches as mementoes of their national service. “They have the potential to pose a significant health hazard to themselves and their families. Smokers are particularly at risk,” Crockett added.
“The watches tested were a mix of British, Swiss and American made items, manufactured between the 1920s and 60s, but we know these sort of paints were used into the 70s,” he explained. “There are potentially millions of these watches in circulation.”
To be clear, some radon in our everyday life is expected and tolerable. It forms naturally thanks to radioactive decay of uranium in rocks and soils, but in high concentrations it can be deadly: in fact, in the UK it’s the second biggest cause of lung cancer after smoking.
To put the study into perspective, the average radon level in British homes is 20 becquerels per cubic metre (Bq/m3), but the worst offending watch – a Swiss-made pocket watch – gave a reading of 1,200 Bq/m3. While this was by far the most dangerous timepiece, two of the watches were in excess of 200 Bq/m3 each.
Professor Gavin Gilmore, the other author of the study, added that collectors should not attempt to open the watches, which could potentially make a bad situation worse. “Loose paint fragments will contain radium particles which could be ingested,” he said. “As this is a strong alpha emitter there is a potentially serious health risk for those who do this.”
What action should you take?
So what should you do with such a watch if you have one? “The best advice is that they should get it radiation tested and get their house radon tested,” Crockett tells me via email. “I would advise that under no circumstances should they dismantle any such due to the risk of releasing radioactive dust/debris which could be inhaled, get into eyes etc.”
He also advised consulting the Radon council website, which provides advice on testing and a list of contractors. “That advice is geared towards radon entering buildings from the external environment but a radon test will test for radon regardless of whether it’s entering a building from outside or emanating from a watch or other object inside,” he explained. “Some of those contractors might be able to also test for radiation emanating from the radium in the paint as well as for radon, but that will depend on individual contractors.”
As the watches tested varied in terms of risk, Crockett has additional advice for wearables which are on the lower end of the spectrum. “Assuming that watches in a collection are not so unsafe that they should be disposed of, I would advise a display or storage cabinet that is (a) sealed from the internal home environment and (b) vented to the external environment, e.g. by an extractor fan.
“Alternatively, a collector could store and/or display in an outbuilding of some sort, but there would still need to be appropriate ventilation to prevent accumulation of radon.”
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