Japan Specific FAQ

We get asked a lot of questions about Japan, here are some that come up again and again and again.

Is it safe for me to visit Japan?

  • Short answer: Most likely.
  • Long answer: Parts of Fukushima are highly contaminated, but in most of the rest of the country radiation levels are no higher and sometimes even lower than other major cities around the world. From our own measurements we can say with confidence that Tokyo and Los Angeles have similar radiation readings and that the levels in Hong Kong are even higher than those in Tokyo. One explanation for this is that Japan had lower average background radiation levels overall than many other places before March 11, 2011, so even with a measurable increase due to the accident, the levels generally still lie within the range what is normal worldwide. It’s also worth noting that air travel, especially transcontinental flights, subject passengers to elevated radiation, sometimes 20 times as much as one might experience on the ground, so it’s very likely that a short-term visitor will be exposed to more radiation on the flight to Japan than they will get the entire time they are on the ground there.
  • One caveat: Food measurements are still largely misunderstood, please see this post for more information about food contamination.

Did the contamination from Fukushima Daiichi spread outside of Japan?

  • Short answer: Yes.
  • Long answer: Traces of particles released by the event at Fukushima Daiichi have been found in every corner of the earth where they have been looked for. The world is a giant ecosystem and when a major contamination event takes place evidence of it can usually be found everywhere. It’s worth noting that there are also remaining global traces of previous nuclear events such as Chernobyl, Hiroshima and Nagasaki, and the widespread nuclear testing of the 1950’s and 1960’s- so much so that there is actually a market for iron and concrete produced prior to WWII for the purpose of shielding environments for isotope identification, as all materials produced after WWII are contaminated and have a higher background radiation level.
  • One caveat: At this point it is generally accepted by researchers that approximately 80% of the radioactive contamination from Fukushima went into the ocean, 18% into Japan, and 2% spread globally.

Are the radiation levels changing?

  • Short answer: Yes, they’re decreasing.
  • Long answer: While occasionally news of a “new hotspot” is reported in the media, the reality is that for the most part these hotspots have existed (at least) since the 3/11 event but just haven’t been detected. Since 3/11 people have become much more aware of radiation and their immediate surroundings and are doing more measurements on their own, and because of this much more detailed data is being gathered, meaning that hotspots which previously may have gone unnoticed are being discovered more regularly. The major contamination from Fukushima Daiichi is Cs137, which has a 30 year half-life, and Cs134, which has a 2 year half-life. Because of this, and the effect of weathering such as rain, radiation levels have already decreased by about 40% in most affected areas. But the contamination will be a problem for decades.
  • One caveat: A new event involving a release of further radiation from any of the reactors at Fukushima Daiichi could result in new contamination. Additionally, the weathering referred to above doesn’t mean that contamination is disappearing, but that it is being moved wherever water flows. Most of it ends up in the ocean, but some is deposited in river and lake beds, where it may remain for a long time.

Is Fukushima Daiichi stable?

  • Short answer: No
  • Long answer: The best available evidence indicates that the melted fuel has lost enough heat that a new criticality event — a nuclear reaction which would release large amounts of radiation — is unlikely. But much is still unknown about the conditions inside the damaged reactors, and independent confirmation of published reports is often difficult to obtain. SAFECAST volunteers have visited the Daiichi plant on several occasions and our maps include data they collected.

    Continuing problems of particular concern include ongoing leaks of radioactive water, the need to move spent fuel rods to safer storage, and breakdowns in the often improvised machinery put in place to maintain cooling and water purification.

  • One caveat: A lot of information is published by TEPCO and by gov’t agencies, but data about some important efforts and results often goes unreported. SAFECAST continues to call for independent verification of all radiation measurements.