Radiation levels around my house

I was finally able to get ahold of a geiger counter this week. I had to return it today because the GPS wasn’t working (I promised to take readings in my area) but with the geiger counter itself I was able to take a few spot readings.

I live in Katsushika – a ward of Tokyo on the far east side, almost in Chiba, near Shinkoiwa station.

The pre-Fukushima natural background radiation of Tokyo was very low by world standards – only about 0.1 µS/hr. By comparison, the natural background radiation of Boston is about 0.34 µS/hr. So you have to consider the changes in the context of world average levels.

Around my house, the new levels are about 0.25 µS/hr ~ 0.4 µS/hr. So since the Fukushima meltdowns, the background radiation level in my neighborhood – more than 4 months after the accident – is about 2.5x ~ 4x what it was before the accident.

While that is disturbing, you have to take into account that the current radiation readings are comparable with Boston. So if you are comfortable walking around Boston there is no reason you shouldn’t be comfortable walking around here.

These readings were taken at heights of 1 to 1.5 meters from the ground, which is a standard height these measurements are taken.

The problem though is that unlike Boston, the radiation levels at pavement level – particularly on concrete surfaces goes up. Apparently, the fallout bonds very tightly with concrete and is almost impossible to get out (until it eventually decays away of course). For example, at the little grocer’s around the corner, above their concrete entryway, the levels were about 0.5 µS/hr. The highest reading I found in my spot-checking was near the bottom of a neighbor’s water drain spout, under a carport with a concrete surface. After about 5 minutes of sampling, the reading settled in near 1.0 µS/hr, which is getting pretty high. Like you wouldn’t want your newborn toddler (which they have) crawling around on the concrete there.

Inside the readings were very low – like 0.1 µS/hr. So obviously it’s very difficult to track in the radioactive particles which are bound in the concrete.

When I get the counter back, I’ll take more comprehensive readings.



Radiation levels around my house — 4 Comments

  1. And my children and grandchildren live in Boston. I think I will tell all our Boston friends to move to Japan. Your family too. Just joking, Love, Muttle

  2. May I ask what model Geiger counter you selected and why?I’m also thinking of getting one. I am wondering what is the best way to measure radiation levels from food.While I agree that external exposure to levels like 0.3 uSv/hr is not harmful, I think the deeper concern is inhaling and/or ingesting the particles that are causing this rise in the usual background radiation. This is where the comparison with Boston deviates.

  3. I wish I could tell you!As mentioned in my note, I borrowed it from a non-profit organization here in Japan to help take readings in my neighborhood, contributing to their database. But the GPS wasn’t working, so they picked it up last night for repairs. I don’t have it handy now to look at the brand name of the actual internal geiger counter they built inside their recording unit.But when I find out I’ll let you know.doug

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