[ RadSafe ] Fwd: Alleged Significant rise in ionising radiation in atmosphere over Southern California

[David & Laura]

We live in the San Fernando Valley, and background radiation monitoring is
one of our hobbies. When the atmospheric plume from Fukushima blew over, we
measured a 3x increase in gamma for a few days (from 0.6 - 0.8 uS
background to >3 uS) before returning back to normal background levels. So
these sorts of changes certainly can be measured with basic equipment, if
operated according to best practices. Of course, attributing the
measurements to specific causes and sources is much more fraught with
difficulty.

One thing to keep in mind is that the San Fernando Valley is immediately to
the west of the former Santa Suzana Field Laboratory, which is a major
local source of nuclear contaminants:

http://www.latimes.com/business/hiltzik/la-fi-hiltzik-20140613-column.html
http://yosemite.epa.gov/r9/sfund/r9sfdocw.nsf/ViewByEPAID/CAN000908498

Walking around the area near our home, we often see hotspots much higher in
background levels, so during windy periods when lots of dust is mobilized,
it certainly is very plausible that measurements of air filters would read
higher rates.

Thanks,

David Slik
VE7FIM

On Thu, Jun 4, 2015 at 6:51 AM, Brennan, Mike (DOH) <Mike.Brennan at doh.wa.gov
> wrote:

> By defining "background" as a clean filter (not unreasonable) I can think
> of several ways of getting the "over 300%" of background.  The easiest
> would be to count a filter as soon as it came off the sampler.  Another is
> to choose a sampling period with som moisture in the air, as it makes
> things stick to the filter.  Sampling during a temperature inversion also
> works.  Or you can "accidently" misrecord the time, so you have a greater
> actual volume than your calculations show.
> ________________________________________
> From: radsafe-bounces at health.phys.iit.edu [
> radsafe-bounces at health.phys.iit.edu] on behalf of Chris Alston [
> achris1999 at gmail.com]
> Sent: Thursday, June 04, 2015 6:38 AM
> To: The International Radiation Protection (Health Physics) Mailing List
> Subject: [ RadSafe ] Fwd: Alleged Significant rise in ionising radiation
> in atmosphere over Southern California
>
> Radon daughters?  Weird "stuff" can happen.  When atmospheric conditions
> were just so, I have seen, e.g., metallic objects, like cars, read to
> dozens of counts per minute alpha, which then vanishes in a few hours.
>
> Cheers
> cja
>
> ---------- Forwarded message ----------
> From: Roger Helbig <rwhelbig at gmail.com>
> Date: Thu, Jun 4, 2015 at 5:36 AM
> Subject: [ RadSafe ] Alleged Significant rise in ionising radiation in
> atmosphere over Southern California
> To: RADSAFE <radsafe at health.phys.iit.edu>
> See
>
> http://www.enviroreporter.com/2015/06/alpha-radiation-clouds-los-angeles-air/
> for the actual report, also look at the About page - these readings
> are being taken by Michael Collins and he may not really know what he
> is doing, but claim to know everything.
> Roger Helbig
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