Q: Is it safe to come to Tokyo? What about other parts of Japan?

A: While we avoid advising people about the decision to come to Japan, all of us are very comfortable living and working in Tokyo, but quite a few people we know and respect made equally well-considered decisions to leave. Contamination is pretty much everywhere in various amounts, but outside of Fukushima and some nearby prefectures (Tochigi, Ibaraki, Gunma) the amounts are minuscule. Virtually no-one we know considers parts of the country further south, such as Nagoya or Osaka, risky places to live.回答: 来日に関する決断について、人々に助言することを避けてきましたが、私達は皆、東京で快適に生活し働いています。しかしその一方で、私達の知り合いや尊敬する、かなり多くの人達が、熟考の末、日本を離れるという決断をしました。汚染は様々な量で、ほとんどどこででも広がってますが、福島とその近県(栃木県、茨城県、群馬県)の外側では、ごく僅かな汚染量となっています。私達の知っている人は誰一人として、名古屋や大阪といった日本の南部が生活するのにリスクのある場所とは考えていないと言っていいくらいです。

Basically, radiation risks are split between external exposures — what will enter your body from the surrounding air or radiate up from the ground, and internal exposures — what will enter your body by breathing or through contaminated food. Our maps show readings that will relate almost exclusively to external exposures. If you compare the levels in Tokyo with those in Hong Kong or Seoul, Tokyo is actually generally lower, even after the Fukushima disaster. In fact there are quite a few places in the world, such as Denver (USA), Cornwall (England), and Kerala (India), whose normal radiation is much higher than Tokyo’s is even now. We have “hot spots” in Tokyo which measure a bit higher than the surrounding average, but the general consensus is that as long as you don’t go out of your way to spend a lot of time in one they are not much cause for worry.
That leaves food. Some of our volunteers take quite a few extra precautions with food, some take less. Food supplies are being checked by the government, by producers, and by independent monitoring groups run by citizens. Safecast has quite a few contacts with various citizens’ groups, and while we do not have our own full-fledged program for measuring food, we keep a close watch on it. We hear about contaminated items being discovered almost daily, but these items are almost always caught before they make it to the market. We would all be surprised, however, if no contaminated food ever ended up on store shelves. But recently reliable data was released by researchers who studied 25,000 people in Fukushima and determined that those who got most of their food from supermarkets, where it was more likely to be adequately checked, as opposed to from their own fields or directly from farmers, had little or no internal contamination. This indicates that the food monitoring has been effective. These people were living in Fukushima, so we can assume that the risks are even lower for people in Tokyo and elsewhere.
We hope this answers basic concerns. Safecast is non-partisan, and takes neither a pro-nuclear nor an anti-nuclear stance. We are simply dedicated to providing easily-accessible, accurate, information about radiation and other environmental hazards. We hope our data helps you to make an informed decision.
The Safecast team
訳: Toshiyuki Arai