As I have written, the Air Quality Management District (AQMD) is posting "daily radiation monitoring updates" in our area and probably in yours as well.
I'm sure the AQMD is a perfectly reputable organization but I want to present some caveats and point out some guidelines when understanding their information about radiation levels.
it comes to radiation, government organizations are capable of having a political
agenda, one of which, understandably enough, is to prevent public panic. If you followed my 2010 blog His Scribe
you may remember that the four-inch thick book of my dad's findings
about the dangers of radiation based on children who survived Hiroshima,
a 3-year research project assigned by the American Atomic Energy Commission, was suppressed by that same commission for five years because
by that time they were testing nuclear weapons and wanted to persuade Americans that
nuclear weapons (ours, at least) were perfectly safe. Once our testing programs were over, they made public
the results of the scientific studies on the Hiroshima bomb.
2. The AQMD is posting daily
information concerning levels of radiation which includes a statement which is a considered opinion about this information. Their
statement is an interpretation of the actual numbers. They report whether there has been an increased risk (not increased levels). However, they cannot really know whether any increased levels pose an increased risk for you.
a. Baseline. As
a baseline they have determined normal background radiation to which we
are all exposed to be 10-12 microrems per hour. I assume this is an average (or mean or median or whatever the term is; I did take a college course in statistics but I didn't think I'd have to remember that term beyond the final) because radiation levels are not uniform from place to place.
I would also bet my socks (if I were a bettin' woman) that the "normal background radiation" levels was much lower
before Hiroshima, Nagasaki, Chernobyl, and atomospheric testing by the
nuclear nations. (I wish I knew where to go for those figures.)
So the AQMD is starting with a baseline that is really higher than normal, at least higher than normal used to
b. Your personal history. Add to that all the radiation you personally have received from
every single X-ray, mammogram, CT scan, etc., you've ever had, including
any cancer treatments using radiation or any radioactive iodine tests or implants in your thyroid. If you work around radiation in a hospital or other facility (even if as a technician you get behind the shield each time it's used), you are bound to be getting some additional low-level (trace) exposure.
Stir in any
additional radiation you may receive because of living either near a
former nuclear testing site (as in Nevada or New Mexico) or living in
the vicinity of a nuclear power plant (remember, radiation does not
distinguish between military and peaceful energy uses).
Also factor in any
appliances that give off radiation. This includes airport security, no matter how small the dose. (I can't speak to
these--microwaves, computers, TVs, VCRs, DVD players, etc. I suspect all of them of exposing us to some additional radiation but I have no idea how much or what kind of radiation, if any, these appliances generate.)
All kinds of factors need to be taken into consideration because RADIATION IS CUMULATIVE and unless the half-life of the source is extremely short, whatever you have will stay in your
body as long as you live.
c. Length of exposure. Since radiation levels in each of us are cumulative, radiation monitoring, to be accurate, has to take into consideration the length of time of the exposure. Microrems are apparently a unit of radiation per hour. But to say someone was exposed to x units of radiation per hour is meaningless unless one knows for how long they were exposed. Were they exposed to that amount for one minute? one hour? Or, like residents of Pripyat, near Chernobyl, for 30 hours or more before evacuation and for their whole lives since then?
Workers shoveling radioactive material off the Chernobyl plant roof were only allowed to be exposed for 45 seconds at a time. But some of them went back to the roof several times. The total radiation they received was exactly the same (unless I'm crazy) whether they got all those 45-second exposures during one work session or many.
Workers on the Fukushima Dai-ichi plant took an hour break at one point and withdrew from the plant (I think it was when there was some flare-up of radiation). But if when they returned to work the radiation exposure present was the same level as before, they didn't start over from zero. The contamination they got subsequent to that hour would merely add to what they had already received.
When our (Reynolds) family deliberately sailed into the Pacific nuclear testing zone in 1958, (I was 14), we were boarded by two Coast Guardsmen who put my father under arrest and, backed up by a destroyer, escorted us to the nearest American Army base.
On my post Phoenix and Golden Rule: arrest, I quote from my father's book, The Forbidden Voyage, about a conversation with these men, who helped patrol the 390,000 square miles of open ocean declared off-limits to American personnel during our series of atmospheric tests.
"The men thought we'd sailed into the test zone by accident and the Navy had assigned them to rescue us. Their
jobs, replacing buoys and marine installations damaged by the tests,
exposed them to considerable radiation but they assured us everything
was under control: 'A man can take one hundred roentgens of
radioactivity per hour without harm.'
"'Oh?' asked Skip [that's what we called my dad]. 'For how many hours?'
"'Well, five or six anyway.'
"Skip pulled out his copy of Shubert and Lapp's Radiation: What It Is and How It Affects You and showed them that an over-all exposure of that much would probably be fatal.
"(Boatswain) Laflin confided that some of the men, in order to get leaves, 'cheated' by putting the radiation badges issued them in their shoes
instead of on their shirts. Skip pointed out that if the deck is the
most radioactive place on the boat, the badges should be placed in the shoes."
There are many kinds of
radiation. I don't think any of them are good for you (although aimed precisely at
cancer, they can kill the cancer instead of you) but they each have different
levels of risk and different half lives. My father was the scientist,
not me. I just know bits from what he shared in books and speeches plus
the reading I have done. But I do know that the more radiation you
are exposed to, the higher your risk of cancer, especially leukemia and
thyroid cancers. I seriously doubt that the AQMD can make a
statement that accurately describes my (or your) personal risk based on
1) background radiation we are all exposed to every day, 2) your exposure history, 3) additional radiation which may be swept across the Pacific from Japan in
air currents and 3) knowledge of how long you have been exposed to that level of radiation.
This is getting long--to be continued. I'll take you through an actual report on the AQMD.gov site.
MANY RELATED POSTS BELOW.