Yesterday Prime Minister Noda visited reactor 4 up at Fukushima Daiichi. Amongst other things, he was seen inspecting the spent fuel pool, yes the one that will supposedly kill everyone when it collapses. The PM was wearing a protective suit, probably a good idea as a precaution, though it might have been more useful were we granted updated reports of actual radiation levels at the plant.
During the day Noda also visited an elementary school in Naraha, a town in Fukushima prefecture within the 20km radius of the plant that is currently undergoing 'decontamination'. There the Prime Minister gave a speech stressing that decontamination efforts must continue in order to 'revive' Japan. According to information released to the media, Naraha is in the 'first zone', which is receiving 'less than 20' millisieverts of radiation a year. Those watching were treated to pictures of workers wearing ludicrous protective masks clearing rooftops of leaves and other rubbish...
It is worth pointing out that moving to Naraha today and living there for a year, you would receive rather less than 20 millisieverts of radiation, because radioactive isotypes have been decaying steadily since the accident, when these radiation estimates were made, and will continue to decay. To my knowledge, radiation levels on the day the measurements were taken were simply extrapolated for an entire year, leading to a yearly measurement that wildly overestimates the actual radiation level. This kind of thing is regularly done when radiation is concerned just in order to be conservative, to be 'on the safe side'. I wouldn't suggest that it is not advisable to have a margin of error, but it is a good idea to keep overestimation in mind when these issues are discussed. In this context, it is a shame that current radiation levels in Naraha town weren't made available on the same broadcast as the Noda speech; that might have been interesting. My guess is that they would be very close to background level in the rest of Japan.
Even if the radiation level in Naraha is accepted as 20 mSv/yr, this is one-fifth of the dose estimated by a plethora of respected international bodies to be the minimum that could possibly expose a human to possible health risks. And we are talking about highly conservative ultra-safe judgements made with the goal a having a wide 'safety margin'. For example, UNSCEAR's conclusions are made reflecting the background of the most rigorous scientific studies on the planet, capable of detecting the elevated cancer risk of a minute fraction of a per cent that results from being exposed to radiation of more than 100 mSv/year, and then only if the most pessimistic of unproven theories of radiation is accepted.
20 mSv/yr is also about one twentieth! of the radiation that residents of Ramsar, Iran receive as natural background radiation every year, without any known deleterious effects. It is no higher than the natural background in many other parts of the world, and comparable to many many others including Denver, Colarado. It is the equivalent of a single chest scan, and much much less than a full-body CT scan; yet medical scans deliver this radiation over a single dose, not spread out over an entire year. Yet nobody seems to be complaining about chest scans, or demonstrating outside hospitals waving pictures of deformed fetuses.
When I think of some of the likely things those workers have done in their lives that have measurably increased their actual risk of cancer before they started cleaning rooftops in Fukushima prefecture I feel a certain amount of righteous anger. Have they ever lived in a major city with smog? Do they eat fried chicken? Drink too much? Go out in the sun? God forbid, did one of them whack a cigarette in his mouth a minute after taking off his mask?
I'm thinking here that if Noda really wants to 'revive' Japan, he might be better off trying to 'revive' a sense of perspective and start dealing with problems that really exist.