Answer to Question #9965 Submitted to "Ask the Experts"

Category: Nuclear Accidents — Fukushima

The following question was answered by an expert in the appropriate field:

I have a son and his family in Japan near Kyoto, which is about 450 miles from Fukushima. How can he get the facts on the degree of safety he has for the future of his young family?

He has a friend who used a Geiger counter to measure radiation at my son's home. It measured amounts that are "three times the normal radiation levels.

Since my son and his family do have the choice to return home to the United States does this level of radiation mean that he should consider leaving Japan?

Please give me your thoughts and tell me how you would advise them if it was your family.
Much has been reported about radiation levels in all areas of Japan. Like you did, people have been scanning with Geiger counters. That’s fine, as long as you realize that there is a wide range of “normal radiation levels." Normal levels depend strongly on the material being measured. For example, the granite counters in my kitchen measure five times higher than the level over wood floors. Granite contains naturally radioactive minerals like uranium and thorium. Regarding your measurements, I would not be alarmed at three times normal. I would take notice at 10 times normal, and try to determine the cause of the increase. The increase may or may not be due to the Fukushima accident. That would have to be determined.

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has released a new map showing the spread of radiation across 10 prefectures, including Tokyo and Kanagawa. MEXT would be a good source of information for your son.

Joel Cehn, CHP
Answer posted on 3 November 2011. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.