BRAWM Team: Potential "Hot Particle" Count In Your Filters

Submitted by Anonymous on Sun, 2011-06-19 18:26

Berkeley Radiological Air and Water Monitoring Forum

Question for the BRAWM team:

If this has been covered already, please point me to the post and I'll read up on it.

I was trying to calculate the potential number of hot particles that could be captured in your air filters for two sample periods during April.

It looks like the air sample volumes in April ranged from:

3.54E+06 liters (04/15/2011 18:02 to 04/16/2011 16:18)

1.15E+07 liters (04/19/2011 18:52 to 04/22/2011 19:04)

Gundersen estimated that the average person breathes in 10 m3 of air a day. And that 10 m3 yielded 5 hot particles in Seattle. I believe that would mean approx. 1770 and 5750 hot particles would be captured in your filters for the 3.54E+06 and 1.15E+07 liter samples (if the samples were taken in Seattle at that time).

3.54E+06 liters / 1000 liters per m3 / 10 m3 per day * 5 particles = 1770 particles

1.15E+07 liters / 1000 liters per m3 / 10 m3 per day * 5 particles = 5750 particles

Are these calculations correct?

If my calculations are correct, based on your knowledge of the hot particle activity, what would you estimate the results to be for either sample? And is that consistent with your results?

Thanks!!!

Yes, your calculations are

Submitted by bandstra on Tue, 2011-06-21 16:12.

Yes, your calculations are correct. We should have thousands of these particles in each of our air filters. Our average flow rate is 3.8 million liters per day (3,800 cubic meters per day), so using Gunderson's estimate, our daily rate would be about 1900 per day.

However, as we've pointed out in other posts, it appears that most of the particles would be alpha emitters such as uranium. We are not very sensitive to alpha emitters unless they are also strong gamma emitters, such as Americium-241. We're currently thinking about how to leverage our filter samples to check for hot particles.

Mark [BRAWM Team Member]

Arnie Gundersen includes

Submitted by Anonymous (not verified) on Tue, 2011-06-21 20:31.

Arnie Gundersen includes Strontium and Cesium in his definition of hot particles according to his last video:

"But this new radiation is in the form of hot particles. What are they? Cesium, Strontium, Plutonium, Uranium, Cobalt 60 and many, many others."

http://fairewinds.com/content/hot-particles-japan-seattle-virtually-unde...

The activity from some of those isotopes would be detectable with your equipment, at least Cesium-137, or am I completely wrong?

What about the EPA?

Submitted by VB (not verified) on Tue, 2011-06-21 17:01.

Thanks for the reply, Mark,

Shouldn't the EPA be able to detect these? And if so, any idea what kind of results could be expected from a filter with up to 4800 hot particles?

By the way, I had a typo in one of my Seattle counts. The 8572 should have been 4286.

1800-4800 a lot or a little

Submitted by VB (not verified) on Wed, 2011-06-22 08:52.

Also, from an activity/radioactivity perspective, is 1800-4800 hot particles considered a lot or a small amount to be captured in a filter relative to what you've been capturing in each filter for the last 3 months?

It depends...

Submitted by bandstra on Wed, 2011-06-22 22:44.

Hi VB, I just did some rough calculations about what activity we should expect in 24 hour air filter samples. If we were to capture 2000 particles of diameter 1 micron, then here are estimates of the total radioactivity in the filter depending on what the particles are made of:

U-238:	0.002 Bq
U-235:	0.01 Bq
U-234:	37 Bq
Pu-239:	400 Bq
Am-241:	15,000 Bq

But it is not clear what the sizes of the particles and their composition would be. By comparison, the activity of Cs-137 in a single air filter for our peak measurement of 1.2E-6 Bq/L was approximately 4.6 Bq. But again, Cs-137 is a strong gamma emitter, whereas most of the isotopes above are not (only Am-241, really). Mark [BRAWM Team Member]

Thanks, Mark!!!

Submitted by VB (not verified) on Wed, 2011-06-22 23:13.

Wow. Thanks for putting in the time to produce these numbers. Really appreciate it.

So, if I'm looking at it correctly, the first two could be difficult to detect. But, the last 3 should be relatively easy. Especially Am-241. Is that correct?

Also, from what you know about the EPA test process, would they have a difficult time detecting these at those levels? They are running a lot more air through their filters for a given sample period though. So, the number of particles should be at least twice the 2000 in your example.

Can someone answer this?

Submitted by Anonymous (not verified) on Tue, 2011-06-21 11:50.

Can someone answer this? Does this mean turning on the air vents and air conditioning in your car will expose you to further hot particles from the filters?

You should change out the

Submitted by T.O. Mom (not verified) on Tue, 2011-06-21 19:51.

You should change out the air filters in your car and in your home. That's what we did.

That's good advice, I would

Submitted by Anonymous (not verified) on Tue, 2011-06-21 19:56.

That's good advice, I would wear gloves and a mask too!

Arnie Gundersen, in one of

Submitted by T.O. Mom (not verified) on Tue, 2011-06-21 23:29.

Arnie Gundersen, in one of his videos, suggested that one should wear a breathing mask and gloves when removing air filters.

Actually, I think Gundersen

Submitted by T.O. Mom (not verified) on Tue, 2011-06-21 23:35.

Actually, I think Gundersen mentioned that one should wear a respirator.

He clearly stated that an

Submitted by Anonymous (not verified) on Wed, 2011-06-22 00:14.

He clearly stated that an iron lung would be advisable.

Are you all serious about

Submitted by Anonymous (not verified) on Wed, 2011-06-22 11:05.

Are you all serious about the need to change car/home filters, or is this a joke? Please advise, thanks.

"Also advising people to

Submitted by Anonymous (not verified) on Wed, 2011-06-22 11:18.

"Also advising people to remove the filters in their air conditioners and the air conditioner in their car, and replace them. Because they pick up particles over the last couple of months and it is a good time to replace them as well. Also telling people don’t do any demolition work. The last thing you want to do right now is tear a wing off your house because you will stir up that dust, not knowing exactly what’s in it, you run a risk of contamination."

http://cryptogon.com/?p=22810

Google is your friend.

Aren't we still capturing

Submitted by Anonymous (not verified) on Fri, 2011-06-24 11:08.

Aren't we still capturing 'hot particles' in filters now? If so, how frequently would we need to change our car air filters/air conditioning filters? Or were the 'hot particles' only really bad in March/April? If my car air filter was changed in May, should I replace it again?

Bump

Submitted by Anonymous (not verified) on Mon, 2011-06-20 09:28.

Bump

I am not part of the BRAWM

Submitted by BC (not verified) on Sun, 2011-06-19 20:11.

I am not part of the BRAWM team, but full respect to them.

Please note that the integers here are negative so so you first measurement is 3.54 - 6 bq/L (the negative sign means move the decimal to the left 6 times) . I have not gone to confirm this measurement, nor the isotope it measures, but that number represents an activity of .00000354 bq/L. So to be clear, the 3.54 E-06bq/L number is LARGER than the 1.15E-07bq/L.

The particles thing is complex. Myself, I am working on how to convert bq or pCi to "particles" (but will settle for g/bq) but the answer is not simple or linear. Seems to me "particles" could be a molecule or a 100 micron super-deadly piece o crud.

BTW, Gunderson has been quite vague, and if there is some data, I want to see it. Now.

For converting Bq to

Submitted by Anonymous (not verified) on Tue, 2011-06-21 01:43.

For converting Bq to particles, please take a look at my calculation here

http://www.nuc.berkeley.edu/node/4602

They were air volume numbers

Submitted by VB (not verified) on Sun, 2011-06-19 20:24.

Hi BC,

The 3.54E+06 and 1.15E+07 were the air volume in liters. Not results. So, it actually is a "+".

EPA Seattle Air Filter Volumes For April

Submitted by VB (not verified) on Sun, 2011-06-19 19:52.

Just thought I'd include the actual EPA Seattle air filter volumes for April.

START END SIZE (M3) Potential # Hot Particles
4/11/2011 4/15/2011 5657.7 2829
4/15/2011 4/21/2011 8572 8572
3/30/2011 4/5/2011 8646.6 4323
4/5/2011 4/11/2011 8648.2 4324
4/21/2011 4/28/2011 9693.7 4847

The EPA says the process names for these were either "Field Beta Radiation Estimate" or "Gross Beta".