Today Hirono’s central government moved back to Hirono. I found out in early January from a friend of mine who works for Hirono city hall that they were planning to move back to Hirono in March, and it looks like they have done it:
Opinions seem to vary about the viability of folks moving back to Hirono. Some are hopeful and look forward to returning, while others are more pessimistic and believe that returning is not an option.
The article mentioned above states “A public Geiger counter near the town hall read 0.42 microsieverts per hour Thursday morning, a level several times higher than seen in Tokyo.”
And since I can’t keep track of microsieverts / millisieverts and what those numbers mean for radiation exposure, I thought I would try to figure it out and put it down here:
sievert = international unit of measure for an absorbed dose of radiation; measures the effect a dose of radiation will have on the cells of the body. 1 sievert (or “Sv”) = 100 rem (the measuring unit used in the U.S.). Receiving 1 Sv all at once will make you sick; receiving 6 Sv or more all at once is most likely fatal.
millisievert = 1/1000 of a Sievert (or 0.001 Sv). For example, a mammogram is 2 mSv, head CT scan 2 mSv, chest CT scan 8 mSv.
microsievert = 1/1,000,000 of a Sievert (or 0.000001 Sv). For example, an arm x-ray is 1 microsievert, a dental x-ray is 5 microsieverts, eating a banana is 0.1 microsieverts (weird, huh?), sleeping next to someone is 0.05 microsieverts.
For a point of reference, the background radiation dose we receive on a normal day is around 10 microsieverts (or 0.01 milliseiverts) The EPA yearly limit for radiation exposure to an average person (i.e. someone who doesn’t work with nuclear reactors) is 1 millisievert a year (or 1000 microsieverts).
For a chart that really provides perspective, check out http://xkcd.com/radiation/.
So if Hirono is currently reporting 0.42 microsieverts/hour, then the annual dosage would be 3.7 millisieverts. That’s equivalent to about a head CT scan and a mammagram. Not that I would want to have both of those in a year, but that’s not too bad.
Maybe that trip to visit them in the fall will indeed happen.