As radiation exposure around the Fukushima nuclear power plant reach levels of 400mSv per hour (although they've since gone down), we thought it was time to put the figures into perspective.
Radiation is all around us, all the time. But what level does it have to get to before it becomes really dangerous?
The World Nuclear Association (which represents the 'global nuclear profession') does have a guide. And while there is a touch of Smilin' Joe Fission, it is a good place to start for a useful primer.
There are different kinds of radiation - which you can read about in the WNA guide. The problems we're concerned about come from ionising radiation.
Radiation dosages are measured in sieverts - but because these are so big we're talking about millisieverts mSv (a thousandth of a sievert). Rather than being an exact unit of size (because different types of radiation have different effects) an mSv measures the effective radiation dose. According to the WNA, each mSv of radiation "produces the same biological effect".
We're exposed to radiation when we fly and when we get medical treatment - and whenever we leave the house. But the large dosages can have dramatic effects.
It has been known for many years that large doses of ionising radiation, very much larger than background levels, can cause a measurable increase in cancers and leukemias ('cancer of the blood') after some years delay. It must also be assumed, because of experiments on plants and animals, that ionising radiation can also cause genetic mutations that affect future generations, although there has been no evidence of radiation-induced mutation in humans. At very high levels, radiation can cause sickness and death within weeks of exposure
So, how high are levels in Japan? @mariansteinbach has been crowdsourcing the levels recorded at monitoring stations across Japan from the the official nuclear monitoring site here. Here are the results (in Grays, which are a unit of size, not of the effective dose received by people in the area). The users have also been monitoring a Geiger counter in Tokyo too (and here's how to read a Geiger counter).
So, how do the levels compare? We've accumulated information from the WNA, news agency reports and medical info site Radiologyinfo.org.
Data summary
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Comments
15 March 2011 3:15PM
Translation: get the fuck out of there right now.
15 March 2011 4:42PM
So we to know something useful we need to know the total amount of Sieverts emitted, or the amount emitted per day.
The peak reading of 400mSV/hour is dangerous if it continues for 20 hours (800mSv), and harmless if it continues for 6 minutes (40mSv).
In other words, knowing the peak reading is the same as knowing nothing.
15 March 2011 6:59PM
'...when we leave the house....'
In parts of the UK with the highest annual doses of natural radiation, these arise from concentration of radon gas within the house. The gas leaks out of the underlying rocks (typically granite) and houses with cellars, where there is often little air circulation, tend to allow it to collect instead of mixing into the atmosphere.
In Scandinavia and Finland, it's a well recognised problem because the houses are so well insulated - air circulation pumps are usually fitted. In the UK, houses are leakier but it can still be a problem and some 10-100s of deaths a year in the UK can be statistically assigned to radon inhalation.
15 March 2011 11:59PM
what is the difference between standing in front of a coal fire or eating a hot coal
being comftable and getting killed from a much lower dose that is breathed into the lungs
Dose is meainingless BIOLICAL interaction is what matters .
There is a huge differance betweeen the source cosmic long wave radiation is no the same as shortwave X-rays even if the energy is the same
The cosmic energy travels through you little effect and travels millions of miles
but a low energy particle kills you and travels max 1 meter.
visit www.llrc.org to understand the difference
16 March 2011 12:50AM
You are talking about an instrument that can give an estimated numerical number but without any value of the biological effect or medical effect of different sources X-ray or ingested particle
Sieviets are a measure of total energy and is based on a flawed model which is based on a single exposure like the atomic bomb after which the DNA gets repaired or the cells detect the damage and die
But if you have a small dose do some damage the allow the DNA time to start to repair, and then another small dose of damage later, then the cells stay alive and you have a much greater chance of mutations and cancer on a lower overall dose.
Plutonium is man made our bodies have no evolutionary history to adapt , where as radon we have a history of natural exposure, as a result same dose of metered radiation gives a much greater toxicity from Plutonium
For example a one off 1 minute Dose in full-body X-ray CT scan radiation reading, 10 millisievert (mSv) is much safer than a total 0.1 mSv over a month from Plutonium radionuclide source contamination particle, and it would be fatal if breathed into the lungs, it glues itself to the lungs cells DNA.
I had a dose just on the chest from an X-ray laser of such low energy that it could not penetrate more than 1 meter of air or 2 cm of flesh at 7mSv per hour and got such an aggressive chest tumour it nearly killed me , but because the energy is low it is called soft X-rays and has been approved for airports by the the NRPB and the IAEC and the same organisations who tell you now that Japan releases is not dangerous because they are paid to tell you lies Cernobile only killed 40 people at the site, when the unpaid NGOs can tell you 1 million died,. The very few scientists and veterans like my self are unpaid and not listened to by a technically ignorant laymen who control the media and the energy policy. ie it is the loyalty to the pay check and the back hander from big capital projects, that we never needed and did not know the true cost. My employer was granted diplomatic immunity and the Nuclear industry has immunity from prosecution and responsibility , they have no Private insurance they can not get it the risk is too big in any country in the world. Lloyd's do not do nuclear power insurance , but Barclay PLC has bought a ware house full of uranium yellow cake to fuel reactors as a speculative move.
Come on Guaridan invite a real expert Proff Chris Busby to write something.
16 March 2011 3:55AM
It is very misleading for your coloured scale of radiation doses in mSv to also
have the measured maximum dose rate in mSv/hr measured at the plant.
To make an apples with apples comparison of a measured instantaneous dose rate with a dose, one needs to know what the time integrated dose is - how long was the exposure - and how did the dose rate evolve over the time of the exposure.
The colours in the graphic give the impression that the yellow dose rate is actually less severe than the amber and red doses - whereas the real picture for some-body who may be exposed to such radiation over many hours and days depends on their actual dose.
Walterw basically says the same thing, but 400mSv/hr*20hours = 8000mSv
which is more than dangerous - probably fatal.
I am an academic physicist with "radiological worker training",
(and more exposure to radiation from medical X-rays etc than my work ..)
and my take on it which basically embodies the public policy in most countries on this is that the general population should not be exposed unnecessarily to doses exceeding 10% of the annual background radiation. This is something like 0.2-0.4 mSv annual dose depending on locale. So I consider a dose of 0.4 mSv of little concern. Contrast this with the 400 mSv/hr *1 hr = 400 mSv of this article. 400 mSv is 1000 times higher than 0.4 mSv.
Maybe you should add a corresponding green bar at the level of
around 0.4 mSv ? (and remove your yellow bar ...)
Now coming back to the real issue - making sure that people in Japan have
a reasonable chance of quantitatively understanding their risk, they need to know what the local radiation levels are - likely many 10's of miles from the power plant where the radiation level will be many times smaller than the elevated levels outside the plant. ( I have seen 8 mSv/hr and 1 mSv/hr in different reports in the last 24 hours).
16 March 2011 5:16AM
I think maybe you shouldn't link to the crowdsourcing spreadsheet on Google Docs. I was viewing it to see the numbers, then eventually clicked on "About," and there it asks people who are not editing to switch to "List View," because only 50 people may look at it at a time in normal mode.
If you send lots of people to the page, then those actually editing the document won't be able to. And there's nothing like an online newspaper citation to send a visitor spike.
16 March 2011 5:56AM
It's clear that the media coverage of this terrible event is being managed and sanitised so that the appalling realities are being introduced in a softly softly way.
I don't know a lot about radiation, but I do find it interesting the way that words like 'meltdown' have been dripped into the coverage. And now 'apocalypse'.
My understanding as a very lay person of Chernobyl, is that there was and continues to be massive radioactive contamination over a large area, including high incidences of birth defects.
The notion that one can 'wash off' radiation...with what? Distilled water, perhaps? seems to smack of the Protect and Survive UK government advice during the Cold War. I seem to recall that the suggestion was to hide under tables.
The numbers of dead and injured in Japan will go up; the severity of the nuclear meltdown will continue to increase, and we will NEVER EVER be aware of the horrific realities which are going down now and for the foreseeable future.
16 March 2011 5:56AM
If a cancerous limit of 100 mSv per YEAR means .0114 mSv per HOUR, (100 mSv divided by 8760 HOURS per YEAR), then 400 mSv per HOUR leaking at the plant, divided by the cancerous limit of .0114 mSv per HOUR, comes to 35,040 times the cancerous limit. —sw2011.03.16
16 March 2011 8:06AM
I typed "Radiation Vaccine" into google and found an article on the "Mechanism of action for anti-radiation vaccine in reducing the biological impact of high-dose gamma irradiation"
"Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after high-dose gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naïve animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days."
So It appears even though radiation can be a serious health risk there are prophylactics available. I wonder why the Japanese Government hasn't administered any?
16 March 2011 8:20AM
Clearly. Stop talking. Some of these comments are hilarious. It's like the Tea Party all over again. Obama's coming for our grannies.
16 March 2011 9:45AM
even if the levels are high and you get any nausea from the radiation ..you doctor if they are like any in england would say ..ohh its just a viral thing goodbye..
16 March 2011 9:52AM
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16 March 2011 10:27AM
JAPAN SDF CHICKENS OUT!
Just picked this up on the English language broadcast of NHK, the Japanese national broadcast network: The Japan Self Defense Forces were asked to fly some of their helicopters in with firefighting equipment, pick up seawater just offshore and dump it over the fires at the nuclear plant. They flew one chopper over, found the radiation higher than expected and decided to abort the mission. They said they might try again tomorrow. Hah! What is going to make the radiation weaker tomorrow if they do nothing today?
If the Japanese people thought those guys would fight to defend the country, maybe they were wrong.
16 March 2011 10:30AM
Wolfenstein:
The Japanese government is actively administrating iodine compounds to people exposed to the radiation, because the first organ affected is the thyroid. They are taking the appropriate first step. The main thing is to put out the fires and stop the radiation.
16 March 2011 10:32AM
Geeze! ADMINISTERING iodine compounds. I must be punchy from watching this stuff.
16 March 2011 11:56AM
Now this IS scaremongering. A simple when it gets to this level(this is where home grown experts can give a considered opinion of what it should be) you should considering evacuating would be enough.
16 March 2011 12:57PM
Hmm
I thought plutonium was pretty safe to look at etc, but whatever you do, don't swallow or breathe even the smallest bit in, as it is then deadly.
Also I thought people living in places with high background radiation had higher tolerance to radiation.
Finally I also thought that exposure to smaller amounts of radioactivity could give some kind of conferred immunity.
Bottom line: about 4 - 8 thousand deaths directly attributed to Chernobyl, 10,000 plus dead as a result of massive tsunami. Frankly you're more at risk by smoking loads and drinking, or crossing a road, or going swimming, or riding a horse. Most people haven't got a clue about risk, witness the MMR debacle etc.
Having said that, I'd be pretty concerned if I lived within close range of the power station.
16 March 2011 1:10PM
It's very important for all people to remember this table not only by the Fukuyima disaster,also by the very increasing risks of repetition of nuclear power engines,already there are each day new plants,and necessary it belong to increasing in energie wells,fully useful to replace the comsumption of fossile oil,much more contaminant and much more dangerous,remember the Deep Horizon disaster and his terribles consecuenses.About the radiation dose and their risks for humans,and also by animals too,it's convenient than all have to remind who these meassurements only meassuring ionizant radiations,however the gamma rays,but also eventually can nuclear fision to emit alpha and Beta rays,therefore there is a need regard the damage that can origin these particles(alpha are protons and neutrons and behta electrons,both capables to produce hurts.Many thanks.
17 March 2011 5:47AM
"It must also be assumed, because of experiments on plants and animals, that ionising radiation can also cause genetic mutations that affect future generations, although there has been no evidence of radiation-induced mutation in humans.'
Wrong.
look at the picture gallery:
http://www.greenpeace.org/international/en/news/features/chernobyl-deaths-180406/
17 March 2011 1:53PM
Can we sort out what sort of radiation is escaping?
Alpha rays travel a few inches - can be stopped by a sheet of paper.
Beta rays not much further.
Gamma rays, like x-rays travel in straight lines until absorbed by something dense.
I suspect, when we read about "radiation" escaping, this means radioactive particles. These emit some or all of the three different rays, and have different life-times (half-lives). The most dangerous are probably alpha emitters. If breathed in they can cause lung cancers.
There will be strong radiation around the plants if the containment vessels are breached, dangerous to thoise in the immediate area, but this will not spread. The danger further afield comes from fire, which will throw particles into the air, and the steam/irradiated sea water which may have dissolved radioactive iodine etc. Please can someone tell us what if anything is coming out of the area?