https://omegaforums.net/forums/vintage-omega-watches-help-discussion-and-advice.23/

I hope the above link opens, it is the recent forum discussion on radium values in speedy 2998's, with links to recent articles on health risks related to radium dials.

I wanted to start a link dedicated to discussing these concerns/issues.

I would like to start with some startling discoveries I have just made about my collection

I currently own 8 radium dial watches, a speedy 2998, 2 early breitling navitimers, two Ranchero's, a Railmaster, a UG tricompax and a Breitling Datora. I have kept these at home in a metal safe. Using a GQ geiger counter I found the baseline room reading was about .15uSv/hr, within baseline. When I opened the safe draw to get a watch the reading (just inside the safe) jumed to about .25uSv, a mild elevation and not very concerning.

After leaving the safe door open for a while, the reading inside safe remained at about .25uSv, suggesting to me that the geiger was detecting particles from the watches, and not radon gas which would have dissipated with the safe door open.

Now for the scary part. I next used my new radon detector that measures radon gas with acceptable range up to 2.7pCi/L. The base line reading in the room was only .1PCi/LNext I put the radon detector in the safe itself overnight and the reading the next day was 500 PCi/L

Holy shit. My interpretation is that radon gas was building up in the metal safe to insanely high levels.

Now! I have no expertise in radiation but it seems that storing multiple radium watches in a safe is a deathwish.

I have just removed these watches from the safe and have placed them in seperate areas around the house and not enclosed. I really have no idea if this is the right thing to do and welcome suggestions (yes, I know I can just sell them all). Maybe my interpretations are all wrong.

I welcome any and all imput

 

As this is an interesting Topic du Jour, I've been motivated to dig a little deeper. I'm glad that you mentioned the Radon gas issue, as, while related, the potential risks are different from those of Alpha and Beta particles, from what I can gather.

The original article published in the U.K. focussed on a collection of vintage military watches kept in a small, poorly ventilated room, and clearly that isn't a good idea. Neither is storing them in a safe, as you have discovered. I will be interested to learn more about the radon gas aspect, as I do not yet have a detector. I have, however, begun to experiment with a geiger counter, and discuss my findings on another forum. Here is a cross-post:

As luck would have it, I coincidentally bought my first radiation detector very recently, and have been testing various watches from my collection. One of the things that has quickly become clear is that there are radical differences between readings taken right on top of the crystal, and those taken in other locations. So, to use one example, I have an Eterna that is quite "hot". Below are the various results, taken with a high-quality Soeks detector, and using readings in μSv/h (i.e. microsieverts/hour). Note that microsieverts are 1000 times smaller than millesieverts, so be careful not to confuse the two while pondering any related results. To be clear, the reading of 15.0 μSv/h (noted below) is equivalent to 0.015 mSv/h.

– directly above crystal = 15.0 μSv/h

– 4" above crystal = 2.90

– directly on the case back = 3.45

– adjacent to the watch = 0.60

So, while 15 μSv/h is a high reading, it is quite clear that even if one were to wear such a watch regularly, the actual accumulated dose would need to be calculated using a far lower level. That is not to say that it would necessarily be "safe", but I believe that it is important not to overreact to the readings taken directly from a dial, or just above the crystal, as no one would be that close to the crystal, or if they somehow were, it wouldn't be for any meaningful length of time.

What interests me the most is how one might calculate, with reasonable accuracy, what sort of dose prolonged exposure to such a watch would produce. For a bit of context, I am going to quote an apparent expert named Mark Foreman, who was responding to a Fukushima thread on another forum a few years ago. Although an event like that and wearing a vintage watch are obviously not closely analogous, I do think that he sheds some light on the topic with his response.

"I would say that 6.7 microSv is not a super nasty radiation field. But it is higher than the occupational limit for an area which the general public has free and easy access to.

If you were to spend 40 hours a week, 52 weeks a year in such a place you would get a 14 mSv dose which is legal for a radiation worker but is on the limit of what you can get in the UK without triggering an investigation of your exposure by the state. That occurs at 15 mSv per year.

In Sweden I think that if you go over 7 mSv in two months or some similar dose then you have to write a letter to SSM explaining what you have done, if you were to stay in this hot spot for two months your exposure would be well below this trigger dose.

At 14 mSv per year you would have to be a classified worker by UK law as you would get more than one third of the occupational limit (20 mSv) per year. This would require you to be placed under medical supervision and you would have to have regular blood tests.

On the other hand this dose is very unlikely to cause any illness unless you remained there a very long time, if you were to spend 20 years in such a hot spot you would clock up 280 mSv which would give you a one on 71 chance of inducing a cancer."

On the same thread, and still using 6.7 uVs/hr as a baseline, Frank Duncan (Chemist, retired, Radiation Safety Officer, retired, Class III Licensed Radiographer in Louisiana, retired) states:

"6.7 μSv/hr=0.77mR/hr so this is above background but well below anything dangerous. You will experience no ill effects from being in a radiation field this low. In the US, you are allowed up to 2mR/hr exposure."

Note that mR/hr is another type of measurement (milliroentgens per hour), but the point should be clear. So, using my Eterna example above, even the close proximity of the wrist to the case back would produce an exposure of roughly half the 6.7 μSv/h discussed by the experts. I therefore infer that even if worn regularly, a relatively "hot" vintage watch would produce only a minuscule cancer risk.

If any readers have deep knowledge of the field, or know someone who does, further insights would be much appreciated!

Cheers,

Tony C.

 

Tony, thanks for the prompt reply. My big concern is really this radon gas exposure, much more so than the particle risks of wearing the watch. I am hoping to learn more about how to mitigate radon accumulation. How best to store these, in a plastic bag, or open to the air? Etc. etc.

 

Yes, I agree that the gas is the bigger issue, and would like very much to hear from real experts in the field.

 

How about buying airtight boxes and storing the radium watches in those ? That’s what I do with mine, and when I want to look I make sure I open the box on the balcony and let the radon clear for a couple of minutes. I think 500 Bq/m3 isn’t actually really high, and besides you’re not breathing in the air from inside your safe so what does it matter ?

I’m also planning on buying an radon detector just to be sure that everything’s good.

 

Could you do an experiment. Put all the watches in a completely airtight box within your safe and measure the radon within the safe. I’d be interested to see if an airtight box can completely seal in radon emissions.

 

Radon gas is significantly heavier than air so opening the box doesn’t make it escape, you have to turn it upside down as if it was water.

 

That sounds a bit unrealistic !

Air is made up of different gases, but they don’t seperate into layers in the atmosphere according to their specific gravity. And outside a bit of a breeze seems very likely to fix the problem.

Anyway, even if your right it’s happy days as I won’t inhale any radon as it will stay in the box even when the lid’s off

Edit to add... actually it is very heavy isn’t it. I just checked and it’s approximately 8 times denser than air under normal atmospheric conditions. Maybe I should swap my futon for a bunk bed.

 

Well, when I open my safe to pick out a watch, am I not breathing in that air for 30 seconds or so (and doing it daily!). Unless you suggest it is so heavy it does not pour out into my face?

 

Well the UK action level is 200 Bq/m3 so your only 2.5 times that. So 30 seconds with your head in the safe is the same as 75 seconds in a house with acceptable radon levels. And those acceptable levels are based on living in that house for probably 3000 hours every year for a lifetime.

What surprises me is that you’re only at 500 Bq/m3. In a really small space with 8 hot watches I thought it might be much higher.

 

Or another way...

You’re in your house for at least 8 hours a day, so 28800 seconds.

30 seconds of 500 Bq/m3 would be the same daily dose as approx. 0.5 Bq/m3 for those 8 hours.

If your watches that you spread around the house increase the ambient level by more than 0.5 Bq/m3 then that’s worse than keeping them in your safe.

Edit: are you sure you’re using the detector correctly ? I just found it stated that air outdoors is typically 5-15 Bq/m3 (where no accumulation occurs) so is it definitely 0.1 in your house ?

 

Well this was after 24 hours, maybe higher if I left it longer? I don't want to find out

 

I just got it and that was the reading after about 3 days. I will keep an eye on it. All new to me.

 

Maybe check the units on your sensor ?
0.1 Bq/m3 really seems to be impossibly low for ambient.

From Wikipedia:

Radon concentration in the atmosphere is usually measured in becquerel per cubic meter (Bq/m3), the SI derived unit. Another unit of measurement common in the US is picocuries per liter (pCi/L); 1 pCi/L=37 Bq/m3.[32]

 

If the watch really reads 3.45 microsievert/hour on the case back, then wearing that watch 12 hours every day gives your wrist an annual dose of 1.5 rem (= 15 mSv), which is not neglible (15 times cosmic radiation background), and roughly in the range of a CT scan. I would not wear that watch more than 10% of the year, and I am a radiation worker. Assuming of course your meter reads correctly. It might also be worth cleaning the watch on the outside, and then measure it again; maybe there's some contamination (dust from the inside, or radon decay products) stuck to it.

Regarding the Radon, to be completely safe, maybe venting the safe to the outside could be done? But I wouldn't be too worried if you can't; you are diluting the activity in the safe by a factor ≥5000 (assuming the safe is 0.2 by 0.2 by 0.2 m, and the room 15m^2 by 2.5m high), so that brings the 500 Becquerel down to a safe level. Maybe avoid taking a deep breath right from the safe after you open it.

 

Just realized my detector is reading in pCi/L !!

 

Thanks, but I just corrected my original post, the radon readings were actually in pCi/L. So really much higher.

 

So instead of 0.1 Becquerel/m^3, you get 3.7, once the air from the safe has mixed with the room air.
Besides the radon gas itself, there will be solid radon decay products plating out on the watches and in the safe. So what might be best is to keep the radioactive watches inside a somewhat sealed box in the safe, open the box outside, and regularly wipe the watches and the interior of the box.

 

Gases that are heavier than air certainly do settle as suggested. This is why for example confined spaces need to be tested before being entered to perform work, such as sewers. For radon this is one reason why the basement of a building is where the greatest risk is.

Sinn fills their watches with inert gas by "pouring" it into the cases...

Cheers, Al

 

WOW
does watch collecting now count as extreme sport ?

jokes aside ... very intersting topic for a nucular noob like me, calling @Seaborg who seems to be also a professionel in this field ....