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Thursday, September 1, 2011

RED RAIN---- My First experience with Radiation from Fukushima with Pictures

Yesterday I exhibited my first major challenge. Things got a little tough.  I was documenting and working with a group of Volunteers and when all of a sudden we experienced RED RAIN (Acid Rain) Geiger Counter was off the charts. We had to take shelter in Temple. Trying to convince a group of University Volunteers that the rain that was falling over our heads was acidic and radiated was a lot tougher than it seems. Apparently the Typhoon that was forecast brought more than what was expected across Tohuku.  The moment it started raining my skin began to burn;  I ran to the car to get my Geiger Counter that International Medcom graciously donated. When I turned it on it quickly began to jump from 100CPMs to 400.  It began to rise quite quickly, at about 300CPM we stopped working, at 1200, yes that's right I said 1200, we were all sitting in a temple out of the rain. We were trapped for about three hours.  I ended up taking  nap.

I  have a few pictures I will be posting  a little later. I have decided to limit my stay in the Ishinomaki and Minami and Higashi- Matsushima to two days until a more accurate assessment can be made. The Irony is that no in the group had any idea to contact. If this is any indication on how bad things may get in Fukushima, I need to consider alternatives to walking. I have a few small burn marks on my legs and arms where the rain hit. I will be positing pictures later.  Thanks.


Measuring Radiation with a Geiger Counter CPM

What is CPM (also the ‘number’ used on the Radiation Network )?

CPM (counts per minute) is a measure of radioactivity, a unit of measurement for a Geiger counter. Technically, “It is the number of atoms in a given quantity of radioactive material that are detected to have decayed in one minute.”
Most Geiger counters are calibrated to Cs137 (Cesium).
1,200 CPM on the meter (for Cs137) is about 1 mR/hr (milliRad per hour).
120 CPM on the meter (for Cs137) is about 1 uSv/hr (microSievert per hour).

How many CPM of radiation is bad?

Answer: It depends on how long you are exposed at any given level. The Radiation Network website, for example, uses a threshold warning level of 100 CPM, mainly because it is unusual to observe levels of 100 or higher without something more going on in the area than just background level.
Having said that, how could one figure out the ‘badness’ of a given level? How bad is bad? All we need to do is put in terms that makes sense.
First, we must understand a few radiation facts and numbers regarding dosage. There tend to be lots of conversions and it can be confusing, but by plodding through the math, you can determine a better idea and relationship of the Geiger counter numbers versus the risks to your health.

Radiation Dosage

Radiation dosage is a measure of the risk of biological harm that the tissues receive in the body.
The unit of absorbed radiation dose is the sievert (Sv). Since one sievert is a large quantity, radiation doses normally encountered are expressed in milliSievert (mSv) or microSievert (µSv) which are one-thousandth or one millionth of a sievert. For example, one chest X-ray will give about 0.2 mSv of radiation dose.
On average, our annual radiation exposure due to all natural sources is about 300 milliRem, which is equivalent to 3 milliSieverts (3 mSv). Adding man-made sources (medical procedures, and others) the average annual U.S. radiation dose is about 600 milliRem, which is equivalent to 6 milliSieverts (6 mSv).
Average annual human exposure to radiation (U.S.)
600 milliRem (mRem)
6 milliSievert (mSv)
Radiation dose for increase cancer risk of 1 in a 1,000
1,250 milliRem (mRem)
12.5 milliSievert (mSv)
Earliest onset of radiation sickness
75,000 milliRem (mRem)
750 milliSievert (mSv)
Onset of radiation poisoning
300,000 milliRem (mRem)
3,000 milliSievert (mSv)
Expected 50% death from radiation
400,000 milliRem (mRem)
4,000 milliSievert (mSv)

What do the Radiation Network CPM numbers mean with regards to health risk?

With the examples of radiation dose listed above, we can correlate how long it would take to experience those effects based on a hypothetical Geiger counter CPM number.
So, let’s use the number 100, since this is the threshold that the Radiation Network website has chosen. The Cs137 calibration factor listed above (120 CPM) was converted to obtain the proper factored results listed below (0.83x). Higher CPM numbers are also listed for relevancy.
Days compared with the avg. annual human exposure (U.S.)
207 (at 100 CPM)
42 (at 500 CPM)
14 (at 1,500 CPM)
2 (at 10,000 CPM)
Days to receive dose for increase cancer risk of 1 in a 1,000
432 (at 100 CPM)
86 (at 500 CPM)
28 (at 1,500 CPM)
4 (at 10,000 CPM)
Days for earliest onset of radiation sickness
25,937 (at 100 CPM)
5,187 (at 500 CPM)
1,729 (at 1,500 CPM)
259 (at 10,000 CPM)

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