Despite catching the worst from the international tabloid corps, best evidence at hand is that competent engineering has taken hold at Fukushima Power Plant.
Japan is now into a fourth day of declining airborne radiation levels.
Not what your teevee has told you ? My, my, my.
TEPCO and the government now say that the Sendai radiation level (to the north in Miyagi Prefecture) is down to 200 nanoGrays/hour. That is in the NORMAL range -- just not quite what monitors show to the south in Hitachinaka City.
Truth takes another step of analysis.
Radiation monitors post output online in Japan. For the solid radiation numbers, a link to "live" numbers connected to the map, and more techie explanation than you need to know... follow below the fold :::
First off, here's the link to "live" radiation numbers:
Japan Radiation Maximum by Prefecture
After you open the link:
-- Resize the map to a "6" or "7" using the slide bar at upper right
-- Click on the Ibaraki Prefecture section (in orange)
-- After a few seconds the detail table will display radiation readings for Hitachinaka City
Metropolis is publishing daily reading for Tokyo HERE.
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Here is the real stuff. Readings are nanoGrays/hour. That's the same as nanoSieverts:
-- 637 nGy/h - 6:50 AM local time on the 19th
-- 749 nGy/h - 1:00 AM local time on the 19th
-- 760 nGy/h - 8:50 PM local time on the 18th
-- 847 nGy/h - 3:00 AM local time on the 18th
-- 856 nGy/h - 1:00 AM local time on the 18th
-- 872 nGy/h - 9:40 PM local time on the 17th
-- 876 nGy/h - 7:20 PM local time on the 17th
-- 881 nGy/h - 4:40 PM local time on the 17th
-- 993 nGy/h - 3:00 AM local time on the 17th
-- 1011 nGy/h - 11:50 PM local time on the 16th
Background radiation for an industrial area should run about 200 nanoGrays/hour.
This is a safe enough environment for adults in the Prefectures bordering Fukushima.. Protect children. Make sure they wear N99 or N100 masks. Stay inside when you can. Running a simple air filter inside your house is a sensible defensive measure. Wash your walls.
These readings are nowhere near danger levels. REM (roentgen equivalent man) is the unit for doses of radiation. It takes collecting 5 REMs over a year for a worker to hit the limit for "safe" laboratory exposures.
You would have to stand outside, not wearing a mask for a year at 875 nGy/h to collect all of a 1 REM radiation dose.
Hitachinaka City is on the coast, immediately to the south of Fukushima Prefecture.
Horiguchi Hitachinaka City is seeing less than 1/1,000,000th of what happened downwind from Chernobyl.
1 Gray = 1 Gy = 1 Sievert = 1 Sv for environmental applications
1 Sievert (SV) = 100 Rem, which means that
1 Gray = 100 Rem
The originally NBS-produced, now NRC-produced and published STANDARDS FOR PROTECTION AGAINST RADIATION states a clear limit: total radiation should not exceed 5 Rem per year.
The highest reported airborne radiation rate in Japan during this crisis got up close to 4,000 nanoGrays-per-hour.
1 Rem = 0.01 Grays
1 Rem = 0.01 * 1,000,000,000 nanoGreys
1 Rem = 10,000,000 nanoGrays
So let's do a bottom-line calculation for what the 4,000 nGy/h max exposure calculates to for a full annual exposure:
4,000 nGy/hour = 0.4 milliRem/hour
4,000 nGy/hour = 0.0004 Rem/hour
Annual total exposure =
4,000 nGy/hour
- times -
24 hours/day
- times -
365 days/year
=EQ =
35,040,000 nanoGrays total annual exposure
Or:
3.5 Rem/year
**
Horiguchi Hitachinaka City is seeing about a sixth of that with a falling radiation level.
Radiation at HHC is running under 1 Rem/year.
This total radiation exposure is sitting well under 1 Rem/year for an Average Person standing outside, unmasked, unprotected. Imagine someone sitting on the pole with the radiation detector.
Some people will get a lighter exposure. A few will get twice the average.
If you live in Ibaraki Prefecture or points to the south, or certainly in Fukushima or Miyagi, do wear a filter-mask. Tochigi, Gumma, Niigata, Yamagata, Akita, and Iwate Prefectures are certainly close enough so that preparations for a wind change are indicated.
The N99 and N100 painters masks are perfect enough.
The simple cloth thingies that people wear to deter flu, not so much.
And do take the potassium iodide pills !
Good luck, everyone !