Just for fun (we all define this differently, as you will see...), I contracted with an industrial hygienist to write up a risk-assessment regarding my exposure to the radon gas that emits from my radium-dialed watch collection. He isn't cheap (about $150/hr), but I intend to share the write-up with the forum once it's been completed.

The only catch is that I don't have a Geiger counter, so I can't give him a relative radium emission for the watches. If any of you can help by posting a reading from your counter, right over the crystal, that would be a big help. Examples that would be optimal are early Speedmasters (like 2998), early Subs (like the pre-Tritium 5508 or 5512), or any dress watches that have Radium dots and hands. Looking forward to what you come up with. Thanks.

 

There are huge variations in the emissions from similar watches. If you are willing to invest $150/h for an assessment, you can add ~$100 for a geiger counter to get the actual reading. I have a Radex One, it works and can function as a dosimeter as well. Although I’m kinda surprised someone doing this type of assessments doesn’t have their own.

 

It seems to me that if you would like a risk-assessment regarding exposure to radon, you would want to measure radon concentrations, not radiation emission from the radium. Why not rent a radon detector, put it in a sealed container with your watches, and track it over time? The engineer will be able to use this information to calculate the rate of radon production.

 

I think we have had this discussion before but I disagree. There is nothing chemically dangerous about Radon. It is a noble gas after all and resolutely unreactive. In addition it only has a half life of at most 3.8 days before decaying into Polonium, Bismuth or another similar radioactive metal. What is actually dangerous are the decay products which have much longer half lives and are solids which form a dust which can be inhaled. It is not the radon itself which is generally the issue, it is the radiation from the Radium decay products products (inc Radon) which needs detecting and monitoring.

 

I've been doing a very unscientific test for the last two weeks with my two radio-active watches ('61 GMT and '51 Seamaster bumper).

You can see the relative geiger readings and the radon meter:

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I live in NJ where we have naturally-occurring radon; my house has a remediation fan (installed when we bought the house in 2014), so I'm currently doing a baseline test in my basement. I'll report back in a couple weeks...

 

I'm not sure what I said that you are disagreeing with. I never suggested that radon was chemically toxic, and the short half life of Ra means that (in a sealed environment) a steady state distribution of radon and its short-lived decay products is reached relatively quickly, which results in ongoing alpha and beta emission. Living and breathing in a sufficiently high steady-state concentration of radon (and its short-lived decay products) puts one at risk for ongoing radiation exposure through long-term low-dose exposure. This is a standard environmental concern in the mining industry or in basements and lower levels of some buildings, where individuals may spend a lot of time. This is nothing new, and it is the main reason that buyers have radon testing done in the basements of houses during a buyer's inspection. That was how I interpreted the OP's risk assessment and the recent article that has been the subject of so much concern. I tend to think that any type of reasonable ventilation will dramatically mitigate the risk, but in any case, the rate of production of radon from radium in the watches represents the data needed for any calculations.

 

Interesting how the Seamaster, with quite a bit less luminous surface area, has twice the radiation reading of the GMT. Makes me wonder...

 

I imagine the seals on a vintage GMT in the Oyster case are superior to the Seamaster.

 

Thats all true and we are probably saying the same thing in different ways but my main point is that it is the radiation which is the threat not the radium, radon, polonium etc so it is that which I would consider the thing needing measuring/monitioring, not the prescence of the gas, which I agree would indeed form a steady state volume as it decays down ultimately towards Lead. AFAIK the commercially available Radon detectors are in fact simply detecting the level of alpha emissions in any case. They don't specifically detect Radon, they detect decay.

 

No expert, obviously, but I would think the seals would affect the radon measurement rather than the radium.

 

Effective cumulative dose from Ra226 or Rn222 encased within your watch or even in picocurie amounts as decay product of Ra226 in air is not clinically significant. It's not even worth discussion, orders of magnitude less effective dose equivalent than limits for medical radiation workers in the US.

To give you a comparison, when we inject the alpha emitter Ra223 into patients with metastatic prostate cancer there is no shield around the syringe, room is not shielded, and the physician is wearing gloves. How much activity? 10^7 times more than in your watch. There are a lot of reasons why this is safe for everyone involved which are beyond the scope of an internet post.

What is being discussed about radiation in vintage watches is in some ways laughable. There's more risk in going outside on a sunny day without sunscreen and driving in DC beltway traffic than there is in your watch, unless you decided to eat your dial and hands.

 

I think you're right, and the topic has been beaten to death. But you may not be aware that the subject has been resurrected by a recent university study. I tend to think that the conditions of the study are a bit extreme, but it has captured people's imagination.

https://www.hodinkee.com/articles/new-report-shows-radium-dials-might-pose-serious-danger
https://www.northampton.ac.uk/news/wwii-military-watches-potentially-pose-serious-cancer-risk/

 

As a demonstration of my statement above about comparing similar watches being meaningless: my Seamaster is basically identical to the one posted above and it reads 15.6uSv/h, a 56% difference, and my Ranchero, with much larger lume markers, reads 12.4uSv/h.

 

The issue is not how much radon is in the watch, or even in the ambient air where the watches are stored. The concern is a very specific scenario: radium watches that are stored in air-tight containers, for long periods of time, and then opened, subject the collector to greater than 500 piC/L of radon. If this is not a concern, even if done repeatedly over the years, it would be great to hear it.

 

I think the differences in the readings can be related to calibration. As any other measurement device, a dosimeter needs to be calibrated. Civilians can hardly do that before a measurement.

For me, it's really not a problem.
Do not forget the amount of Radon is really small such just as it's half life.

Dr. R.

 

My interpretation of the study was to simulate a scenario where someone might live/sleep in a small sealed/un-ventilated room that houses a watch collection. In this case, he would be receiving continual exposure, not occasional transient exposure. The occasional transient exposure scenario is obviously also possible (and probably more realistic), but doesn't represent a significant risk. However, I want to make it clear again that IMO the assumptions of the study represent a very extreme worst-case scenario.

 

Not concerning.

 

Me opening the box containing my Ra(so Rn)-bearing watches .

 

Did you pick this up in the sales forum?

 

Okay, you three seem to have consensus here. If it were you, and you were opening these sealed parcels, would you: open it with no regard; open it while holding it under an exhaust fan; or open in a ventilated room, and exit it for a time? Apparently, many keep these watches in safes, so the answer would have practical applications.