Wednesday, March 16, 2011

Day 5, March 15: Radiation Levels in Tokyo--we are safe

Hello Everyone,

The situation at the Fukushima reactor has been making big news around the world (and indeed in Japan as well), in some cases quite sensational news. So I thought it would be good to give some perspective on the situation.

The group at the CRASH quake relief command center has been monitoring the situation, and the team leader has sent out the information below which may be helpful to those concerned about the radiation leaks from the reactors.

I too have seen some news articles such as "Radiation levels shoot up in Tokyo, vicinity", which sounds quite serious until one realizes that normal levels are very very low. In Saitama where I live they reported "40 times higher than usual", but it was only a figure of 1,222 nanosievert per hour, which is 1.222 microsievert, or 0.0012 millisievert (if I've done my math correctly). Even the article quoted above with the sensational title stated "But those levels did not pose immediate danger to human health, the Ministry of Education, Culture, Sports, Science and Technology said."

At the level quoted you would need to be exposed for at least 208,000 hours before there would be any noticeable effect (at the lowest level of 250 millisieverts), which is why most reports "stressed that that such a level posed no immediate health threat, and that levels had dropped since then."

At that rate you would need to be exposed for about 33 hours (outdoors) to equal the amount absorbed by one chest x-ray.
Jonathan Wilson posted a new message:
Radiation Levels in Tokyo

- 0-250 millisieverts: no obvious effect
- 250-1000 millisieverts: temporary nausea, damage in blood cells, sterility among men
- 1000-3000 millisieverts: death is possible

Fukushima power plant: radiation dosage of up to 400 millisieverts (dangerous)

Tokyo (Shinjuku): highest level detected was 0.809 microsievert (10 am, 15th)
(in comparison, Chest X-Ray: 40 microsieverts are absorbed)

A microsievert is 1000 times less than 1 millisievert. Although the radiation has risen in the Kanto area and it's good to be cautious, it's also advisable to stay calm as it is not an immediate risk to human health.

Sources: ... od-bad.pdf ... 315z2.html

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