So we read news that the radiation level in Tokyo following the nuclear plant explosions at Fukushima (explosion at nuclear reactor 1 occurred on Saturday, 12 March, the day after the earthquake-tsunami catastrophe; and a second explosion at nuclear reactor 3 occurred on 13 March, Sunday), has risen 20 times, but still at a safe level. The next questions that come to mind but are not expanded on by these journalists are: What is this level? What is the safe level? At what level is it not safe?
The exact units of measurement vary, but light radiation sickness begins at about 50–100 rad (0.5–1 gray (Gy), 0.5–1 Sv, 50–100 rem, 50,000–100,000 mrem). The SI unit of radiation dose equivalent is the sievert, 1/1000 of a rem (1 mrem = 0.01 mSv). — Wikipedia
At a facility in Shinjuku Ward, a maximum level of 0.809 microsievert was detected at around 10am, but the hourly level went down to 0.151 microsievert after 11am (16 March, Wednesday). These figures compare with 0.035 to 0.038 microsievert detected Monday (14 March). Fifty (50) microsieverts is absorbed when one takes a chest X-ray. — Japan Times
So when journalists say that the radiation level in Tokyo has increased 20 times but is not detrimental to your health, the “not detrimental to your health” phrase doesn’t sound believable because the “20 times” sounds “detrimental” to your health. Except for the article in the Japan Times published Wednesday, all other articles on Tuesday using this phrase (that the “radiation levels has increased 20 times but is not detrimental to your health”), do not mention numbers and figures to substantiate their affirmation, only that stressful number “20 times.”
Little does the unsuspecting public know that 20 times of the fraction .04 mSv is .80 mSv. Based on the above maximum level, 80.9 mrem, computed as 0.01x mrem=.809 mSv, is significantly less than the 50,000 mrem, the level where radiation sickness occurs.
In conclusion, when journalists of dubious intelligence report that the radiation levels have risen 20 times without substantiating numbers or figures or calculations, they are SENSATIONALISING the news, causing a panic situation that affects business very badly and consequently, our financial future.
Radioactivité au Japon et en France
March 16, 2011 at 1:38 pm
There is a serious problem with misquoting microsievert vs millisievert in the news.
Not saying you’re wrong but there has been quite a bit of confusion around this. The 0.809 number could well be 0.809 millisievert …. or 809 microSv, still not ridiculously high but more of a concern.
March 17, 2011 at 11:54 pm
Here are the conversion equivalences:
* 1 Sv = 1000 mSv (millisieverts) = 1,000,000 μSv (microsieverts) = 100 rem = 100,000 mrem (millirem)
* 1 mSv = 100 mrem = 0.1 rem
* 1 μSv = 0.1 mrem
* 1 rem = 0.01 Sv = 10 mSv
* 1 mrem = 0.00001 Sv = 0.01 mSv = 10 μSv
If you watch the news in Japan, the translator will say microsieverts.
SI multiples are the millisievert (1 mSv = 10−3 Sv = 0.001 Sv) and microsievert (1 μSv = 10−6 Sv = 0.000001 Sv)
(from Wikipedia)
March 23, 2011 at 6:17 am
Which is correct? Are they saying micro, when they really mean milli? Hopefully “micro” is correct. That would paint a much better picture.
March 27, 2011 at 2:11 pm
I look at the Tokyo geiger in Ebisu near where I live. its in uR/Hr. http://www.alttokyo.com
I need to look at an up to minute chart at night and when I get up in the morning. They send email alerts too which is a bit of a relief, but anyway I am more concerned with food/water contaminates rather than background radiation. I now 2nd guess what restaurants source their vegetables.
March 29, 2011 at 6:17 am
No one is talking about Sendai! What’s going on there. They’re always talking about Tokyo. I’m interested in what the levels north of Fukushima are – Sendai in particular. Anyone know?
April 9, 2011 at 12:27 pm
Maximum radiation levels in eastern Japan as of 9 April:
http://www.japantimes.co.jp/radiation-levels.html
April 7, 2011 at 5:56 pm
Not sure what the worry is all about in Tokyo… around here between Sheffield and Manchester in the UK, you could get 15mSv (milli) of radiation from a total of 14 hours of doing recreational caving… (or working in one)
0.8 mSv, here, is natural background radiation…
It’s not news that it is 20 times greater than Tokyo’s background radiation…
What’s being pumped into the sea around Fukushima is very high tho…
April 8, 2011 at 9:26 am
Is there any talk about capping the reactors or dumping cement and boron (and whatever other chemical they need to) on them? It would seem to me that they are fighting a battle that cannot be won. Or do they have to wait until the reactors cool? Bless them for trying so hard at great sacrifice.
April 8, 2011 at 9:43 am
They’re injecting the reactors with nitrogen to prevent them from exploding, as well as pumping water to cool them down.
April 8, 2011 at 7:41 pm
Fukushima Nuclear Accident Update by the IAEA (International Atomic Energy Agency):
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
April 15, 2011 at 12:02 pm
I just returned from the Sendai coastal area. While up there (three weeks) my group used both two American made Gieger counters which showed very low levels during most of our stay. However, I wouldn’t say these were 100% accurate – they were old and supposed to be Zeroed in a completely neutral area, but they were Zeroed in at Tokyo after the disaster took place. However they gave us a pretty good estimate and, as expected, went into the red zone when driving up past Fukashima. I personally used an I-phone App, “Radiation Map,” which is based around continuous readings by local individuals and companies in different areas up and down the coast above and below Fukashima. The readings in many areas are still very low, .0003sv for example. There were only two days in Sendai when I could feel that the radiation was level higher and confirmed that with readings (Yes, you can feel radiation despite what any “experts” say. It’s not too different from that prickling sensation you get when the sun is a bit stronger than usual. The radiation levels varied from day to day depending on wind direction and rain fall). Having said all that, it’s not the single dose of radiation that’s dangerous – unless you’re silly enough to be standing next to an atomic blast. It’s the cummulative effect of radiation that eventually wears the body down. One web-site mentioned annual limits of .50sv as safe but I don’t know enough about that; my guess is that it varies from person to person.
Hope that helps,
BR,
Simon