New study says Minami-soma as safe as Western Japan cities – do they really expect us to believe this?


On September 5, 2017, Minami-soma city made a statement on the city’s radiation levels compared to 3 cities in West Japan, which has been reported in several newspapers. It’s important to comment on this study because the statement is intended to persuade the population to return to live there.

We are publishing comments on the articles below after having discussed with M. Ozawa of the citizen’s measurement group named the “Fukuichi Area Environmental Radiation Monitoring Project“. For English speaking readers, please refer to the article of Asahi Shimbun in English. For our arguments we refer to other articles published in other newspapers – Fukushima Minyu and Fukushima Minpo – which are only in Japanese.



Here are the locations of Minami-soma and the 3 other cities.

map 4 cities

Here is the article of the Asahi Shimbun

Fukushima city shows radiation level is same as in west Japan


September 5, 2017 at 18:10 JST

MINAMI-SOMA, Fukushima Prefecture–Radiation readings here on the Pacific coast north of the crippled Fukushima No. 1 nuclear power plant are almost identical to those of sample cities on the other side of Japan.

The Minami-Soma government initiated the survey and hopes the results of the dosimeter readings, released Sept. 4, will encourage more evacuees to return to their home areas after they fled in the aftermath of the 2011 nuclear disaster.

A total of 100 portable dosimeters were handed out to 25 city employees from each of four cities–Minami-Soma, Tajimi in Gifu Prefecture, Fukuyama in Hiroshima Prefecture and Nanto in Toyama Prefecture. They were asked to take them wherever they went from May 29 through June 11.

The staff members were evenly dispersed with their homes in all corners of the cities they represented.

In addition, only those living in wooden houses were selected as different materials, concrete walls, for example, are more effective in blocking radiation.

In July 2016, evacuation orders for most parts of Minami-Soma were lifted, but not many residents have so far returned.

The city’s committee for health measures against radiation, which is made up of medical experts, analyzed the data.

The median value of the external radiation dosage of the 25 staff of Minami-Soma was 0.80 millisieverts per annum, while the average value was 0.82 mSv per annum, according to Masaharu Tsubokura, the head of the committee and a physician at Minami-Soma general hospital.

No significant difference was found in the three western cities.

Both figures were adjusted to include the natural radiation dose, and are below the 1-mSv per annum mark set by the national government as the acceptable amount of long-term additional radiation dosage, which is apart from natural radiation and medical radiation dosages.

The radiation doses in all cities were at levels that would not cause any health problems, according to Tsubokura.

“Making comparisons with other municipalities is important,” Tsubokura said. “I am intending to leave the survey results as an academic paper.”












Our comments

1) The difference of life style between city employees and local agricultural population
As we see in the article, portable dosimeters were handed out to city employees. They spend most of their day time in an office protected by concrete walls which are efficient for blocking radiation as stated in the article. However, in Minami-soma, most of the population spends more time outside, very often working in the fields. Their life style is different and therefore the external radiation dose cannot be similar to those of city employees. The result of the comparison between the external radiation dose of city employees cannot be used as an argument to say that it is safe for the local population to live in Minami-soma.


2) In the article of Fukushima Minyu, it is stated that in Minami-soma the radiation dose has a wider range than in the other three cities. This means that there are hotspots, which leads to higher risks of internal irradiation.


3) The radiation dose expressed in terms of Sieverts is relevant for radioprotection when the source of radiation is fixed and identified. This is the case for most of the nuclear workers. However, in the case of Fukushima after the nuclear accident where the whole environment is radio-contaminated and the radioactive substances are dispersed widely everywhere, it is not a relevant reference for radioprotection. It is important in this case to measure surface contamination density, especially of soil.


4) 6 years and 6 months since the accident, cesium has sunk in the soil. It is thought to be between 6 and 10 cm from the surface. This means the top layer of soil from 0 to 5 cm is blocking the radiation, reducing the measures of the effective dose. However, this does not mean that the population is protected from internal irradiation, since cesium can be re-scattered by many means, by digging or by flooding, for example.


5) The reliability of individual portable dosimeters has already been raised many times. This device is not adequate to capture the full 360° exposure in radio-contaminated environments as described in point 3 above.


6) In the article, it is stated that background radiation is included in the compared values, but it does not mention the actual background radiation measurements in the 4 cities.


The Table of Fukushima Minyu

Radiation dose of the 4 cities


Median values

Sum of the dose (microsievert) Conversion to annual dose (milisievert)
Minami-soma 31.44 0.82
Tajimi in Gifu prefecture 27.55 0.72
Fukuyama in Hiroshima prefecture 30.41 0.79
Nanto in Toyama prefecture 30.91 0.81

Values include the background radiation dose


Capture d_écran 2017-09-06 à 19.45.12

To summarize, the sample study group does not represent the overall population. The study doesn’t include the risks of internal radiation, for which the measurement of contaminated soil is indispensible. The dosimeters are not adequate to measure the full load of radio-contaminated environments. So, the research method is not adequate to draw the conclusion to say that it is safe for the population to return to live in Minami-soma.

要約すると、サンプルグループが全体の人口の代表していないこと、調査が 内部被ばくのリスクを考慮していないこと(内部被ばくのリスクのアセスメントには土壌汚染測定が必須)、小型線量計は放射能汚染された環境の全体的な測定には不適格であることなどが挙げられます。結論として、南相馬に帰還しても安全という結論を導くには、この調査方法はとても適切とは言えません。

Olympic games in Fukushima: Is it safe?


Fukushima city is going to host Olympic baseball and softball games in 2020.
What is the level of radio-contamination there? This is the question on everybody’s mind, spectators and players from all over the world. Is it really safe?


Baseball and softball games will take place in Azuma Sports Park in Fukushima city.



あづまgoogle map ENG




Fukushima prefecture provides the information below on the radiation measurements of the Park.




Measurements of the airborne radiation dose in the baseball stadium: No 13-16
Those of the softball stadium: No 4
The lines above and below indicate the value of the radiation dose at 1cm and 5cm above the ground.

We notice that, as usual, Fukushima prefecture gives only measurements in terms of radiation dose. Based on this information, one might think that it would be relatively safe to play there or to attend the games. However, monitoring only the radiation dose is not enough for radioprotection. The radiation dose is an indication of external irradiation exposure. In this case, the measures of radioprotection will be to stay away from the radioactive objects or not to stay in their vicinity for a long time. But the radiation dose does not provide information to avoid the risk of internal irradiation. For this latter, it is necessary to monitor surface contamination density or concentration, in this case, of soil (in terms of Becquerels/m2 or Bq/kg), as well as the concentration of radioactive substances in the air (Bq/m3). The radioprotection measures against internal irradiation would be wearing protective gear and masks to avoid the radioactive substances from adhering to the skin and/or entering the body.

よくあることですが、福島県は空間線量率しか公表していません。この情報だけ見ると、そこでプレイしても、観戦に行っても安全であるような印象を受けます。しかし、空間線量率だけを見ていては、放射線防護には十分ではありません。空間線量率は外部被ばくを避けるために参考になる数値です。この場合、放射線防護の方法としては放射性物質から遠ざかる、滞在時間を短くする、などがあります。しかし空間線量率は内部被曝のリスクを避けるための指標には適していないのです。内部被曝の場合は表面汚染濃度、密度(平米やキログラムあたりのベクレル数値)や空間に浮遊する放射性物質の濃度(cm3 やm3あたりのベクレル数値)を参考にしなければなりません。この場合放射線防護の手段としては放射性物質を体の中に取り込まないための、服装やマスクを装着するというものになります。

Here is some information provided by Yoichi OZAWA of « Fukuichi Area Environmental Radiation Monitoring Project », the group of which we have published several soil contamination maps in this blog. OZAWA took measurements on July 27 at the request of the ARD German TV channel team which was visiting Fukushima.



PowerPoint プレゼンテーション

Contamination concentration and density of 5cm surface soil around the Azuma Baseball Stadium

Point A : The entrance of the « Torimu no Mori» where children play.
Radiation dose at 1m above the ground : 0.12 μSv/h
Radiation dose on the ground : 0.19µSv/h
Surface concentration : 605 Bq/kg
Surface density : 47,300 Bq/m2

Point B : In front of the Multi-purpose Fields.
Radiation dose at 1m above the ground : 0.10 μSv/h
Radiation dose on the ground : 0.22µSv/h
Surface concentration : 410 Bq/kg
Surface density : 31,200 Bq/m2

To interpret these figures, let us remind you that in Japan, according to the Ordinance on Prevention of Ionizing Radiation Hazards, places where the effective dose is likely to surpass 1.3mSv in 3 months (approximately 0.6µSv/h of airborne radioactivity) or the contamination density to exceed 40,000Bq/m2 are designated as a « Radiation Control Zone » and public entry must be severely restricted. People under 18 years old are not allowed to enter, and even adults, including nuclear workers, cannot stay more than 10 hours. It is prohibited to eat, drink or stay overnight. To leave the zone, one has go through a strict screening to check for radioactive substances leaving the zone, a measure to protect the individual person as well as the environment.

これらの数値がどの程度のものかを知るために日本の電離放射線障害防止規則を参考にして見ると、外部放射線による実効線量と空気中の放射性物質による実効線量との合計が、3ヶ月につき1.3mSv(概算0.6µSv/h)を超えるおそれのある区域、 あるいは 放射性物質の表面密度が40000Bq/m2を超える恐れのある区域は放射線管理区域と呼ばれます放射線管理区域では 飲食は禁止、寝泊まりもできません。原発労働者なども含む成人でも10時間以上の滞在は許されません。そこから出るときは厳格なスクリーニングを受けなければなりません。

We do not have the measures of surface density of the baseball nor softball stadiums, but in answering the question of the above German TV team, the information was given as to the decontamination work and radiation dose. There had been decontamination work, and the airborne radiation dose was about 0.04µSv/h in the baseball stadium.


Even when decontamination work has been carried out in the stadium, the mountains and woods behind the park have not been decontaminated, and wind and rain bring the radioactive substances towards the park. Besides, as we can see above, other places in the park are highly contaminated when we look at the surface contamination. They represent high risks of internal irradiation. Moreover, according to recent research, radioactive particles disseminated by the Fukushima Daiichi nuclear accident are mostly insoluble in water. This characteristic makes the health hazard much worse than in the case of the usual water soluble Cesium (see English transcription of NHK documentary on Insoluble Radioactive Particles in this blog). We believe that this Park should not be open to the public, especially to children.


The small type of insoluble radioactive particles – also called Cesium balls -, are dispersed in the Tokyo metropolitan area. People who visit this area should be careful and should take adequate radioprotection measures especially when it is windy and the radioactive particles can be re-disseminated.


All in all, we believe that there is far too much risk for the players and spectators to participate in the Olympic games in Fukushima. Fukushima should not host the Olympic games. Furthermore, we are against holding the Olympic games in Tokyo.



Read also – こちらもご参照ください:

Forest fire in the exclusion zone in Fukushima: Why monitoring the radiation dose is not enough for radioprotection

See the publication of August 4 2017 in the FB of Oz Yo
Oz Yoさんの8月4日のFBページ参照。

No human rights in terrifyingly contaminated Namie in Fukushima


The evacuation orders of the most populated areas of Namie, Fukushima were lifted on March 31, 2017.
We are publishing the most recent soil surface density map of Namie created by a citizen’s measurement group named the “Fukuichi Area Environmental Radiation Monitoring Project“. Their members are mainly from Tokyo metropolitan region.

Namie-20170722 土壌汚染地図 ENG S

主として首都圏に在住の市民の皆さんが作っておられる団体「ふくいち周辺環境放射線モニタリング・プロジェクト」が浪江町の最新の 土壌汚染マップを作成されましたので、ここに投稿させていただきます。

20170722-namie-38+39+40+41(0721-3)-s JP

This map is simply terrifying. This is far much higher level of radio-contamination than in the Radiation Control Zone. Any area becomes designated as such when the total effective dose due to external radiation and that due to radioactive substances in the air is likely to exceed 1.3mSv per quarter – over a period of three months, or when the surface density is likely to exceed 40,000Bq/m2. In the Radiation Control Zone, it is prohibited to drink, eat or stay overnight. Even adults, including nuclear workers, are not allowed to stay more than 10 hours. To leave the zone, one has to go through a strict screening.

Namie’s radio contamination is far over these figures! The average soil contamination density of the total of 314 points where the soil was collected and measured is 858,143Bq/m². The maximum value was 6,780,000Bq/m², and the minimum was only 31,400Bq/m²!


浪江町の放射能汚染はこの数値をはるかに超えるものです。土壌採取と測定がなされた全314ポイントでの 土壌汚染密度の平均は 858,143Bq/m²、最大が 6,780,000Bq/m²で、最少でも 31,400Bq/m²です。

And people, including infants and pregnant women, are told to go back to these areas to live, because it is supposed to be safe. Basically the Japanese government does not recognize the fundamental human right to live in a healthy environment. The population is facing a tough future, for the compensation will be cut off soon, and the housing aid by the central government finishes at the same time. As for the auto-evacuees who fled from areas which are not classified as evacuation zones but are nevertheless radio-contaminated, they had only very little compensation and the housing aid was cut off at the end of March 2017. Continuing to live as nuclear refugees is becoming more and more difficult. We consider that this is a violation of basic environmental human rights.

このようなところに、もう安全だから、と言って、幼児や妊婦も含めた人々を生活するために帰還させようとしているのです。基本的に日本政府は良好な環境の中で生活するという、国民の環境権を認めようとしていません。原発事故被災者の皆さんの将来の見通しは困難なものです。精神的損害賠償という名称の賠償は来年3月に打ち切りになり、政府による住宅提供も同時に打ち切られてます。避難指示区域外からの避難者、いわゆる「自主」避難者、または自力避難者については、政府による住宅提供は2017年3月末にすでに打ち切られています。原発事故避難者として生活を続けることはますます困難になりつつあります。 これは基本的人権の一つである、環境権の蹂躙であると考えます。

Let us not forget to thank the members and volunteers of the Fukuichi Area Environmental Radiation Monitoring Project team. They are mostly elderly people over 60 years old. However, that doesn’t mean that they can be exposed to radiation. We thank them and pray for their health.


You might think that Japanese just endure their fate without complaining. This is not true. Many people are fighting and protesting. Let us cite, among numerous on-going trials, the one called the “Trial to require the withdrawal of the 20mSv dose as the limit for evacuation” filed by residents of Minamisoma city in Fukushima, who are against the lifting of the evacuation order when the radiation dose decreases below 20mSv/year. Let us remind you that the Japanese government has adopted 1mSv/year, the internationally recognized dose limitation for public recommended in 1990 by ICRP (International Commission on Radiological Protection), and this is still the limit for the public all over Japan EXCEPT in Fukushima. This is one of the reasons why many people from Fukushima ask themselves: “Is Fukushima really a part of Japan?” or “Are we the people abandoned by the State?”


Related articles of this site.

Forest fire in the exclusion zone in Fukushima: Why monitoring the radiation dose is not enough for radioprotection

The scandalous deficiency of the health scheme in Fukushima

Incredible contamination in Namie, Fukushima

New data show massive radiation levels in Odaka, Minamisoma