I don't think this is the mood to talk about these days. Japan Fukushima radioactivity story. Recently, some media have been covering Fukushima. There are reporters who go to Azuma baseball field in Fukushima. I'm playing baseball in Fukushima next year at the Tokyo Olympics. Reporters took radiation dose meters. These instruments usually give readings in units of sivert (1 m㏜ = 1,000 μ㏜). It is a unit that knows the exposure to the human body.
This is a video from a sidewalk. 0.50μ㏜ / h. This means that 0.5 microsieverts of radiation were measured per hour. We measured near Fukushima Azuma baseball field. These meters usually raise the readings closer to the object containing the radioactive material, and lower the readings away. The sidewalk didn't tell you exactly how high it was on the ground. It is reported that the figure is 0.5, more than twice the safety standard of 0.23. It is dangerous. There are many reports of this logic in other media as well.

● Is 0.23 'Japan' safety standard '?

Is 0.23μ㏜ / h a safety standard? Will it be dangerous if it exceeds 0.23 and is it safe if it is not above 0.23? It is not. This means that the human body receives 0.23 microcivertes of radiation per hour, not a number that can determine whether it is safe. If the number 0.23 itself represents a safety standard, it would be dangerous and uncomfortable for the reporter to navigate the site without the radiation-blocking equipment at 0.5. But the reporters went near the Azuma ballpark without any equipment and went on the air. Some reporters wore some masks, but that doesn't prevent radiation.

0.23μ㏜ / h is the number that the Japanese government has set as its target. It means reducing the level of radioactive contamination in Fukushima by 0.23. Since 2011, we have been working on decontamination, or decontamination, but as it is still in progress, radioactive substances can be detected in mountains, land and rivers. We will reduce the dose from those radioactive materials and the exposure to the human body to 0.23, the target number is 0.23. Just 0.23 is safe, so it doesn't mean that it's going to clean up that much.

● Why is it 0.23, not 0.22?

Why is it not 0.22, not 0.24, and is it 0.23μ? / H? I found out, it took a few calculations. In simple terms, first divide the annual exposure dose limit of 1m㏜ by the public. Then you get the daily dose limit. Dividing it by 24 again gives us the dose limit per hour. But since people aren't living outside 24 hours, and they move in and out of their homes, they make a slight change in their calculations, taking into account the reduced exposure when indoors. So if you live for one year in an environment of 0.23μ㏜ / h, you will receive 1m㏜ of dose per year. So 0.23.

● Isn't it dangerous if it exceeds 1m / year?

I told you that 0.23μ㏜ / h is not a safety standard, which means that 1m㏜ per year is not a safety standard. However, the Japanese government will manage it not to exceed 1m 연간 per year, so if you exceed 0.23, you might wonder if it is dangerous. However, there is no scientific evidence that if it is above 0.23, it is dangerous. Similarly, it is okay to be exposed to 1m㏜ per year, and it is difficult to say that from 1.1m 부터 to dangerous. The number 1m㏜ is a man-made radiation protection management figure.

Several studies have been conducted, including victims of previous Chernobyl nuclear accidents. So far, it has been 'proved' that radiation dose and cancer incidence are proportional to more than 100 m㏜. Beyond 100 m㏜, the greater the exposure, the higher the incidence of cancer. By the way, assuming that 0.5μ㏜ / h as measured by the reporters in Fukushima now, this will be 4.4m㏜ per year. This is assuming 100% external living and decreases with longer indoor living times. It is lower than 100 m㏜. So it's not wrong to say "it can be dangerous," but the average listener often accepts it as "dangerous."

● 'home' for public safety

To put it more precisely, it is correct to say that it is "unchecked" as to whether it is "dangerous" if you live in an environment of 4.4 m2 per year, that is, if you build a house in front of Azuma Ballpark and go in and out for 24 hours. What we do know is that we do not know exactly. However, many experts in low-dose environments below 100 m㏜ and the majority of the press 'assumed' that the greater the exposure, the greater the risk is. Because it meets public safety. Assuming that you are at risk, reducing your exposure as much as possible means that it is not good for our health. Perhaps that's why we're reporting 0.23 as a 'safety standard'.

● Fukushima mask, increase the risk of cancer every day?

There have been noticeable reports in this context recently. "A week in Fukushima increases the risk of cancer every day." Several media have cited the Los Angeles Times in the United States. This is in line with the general fear of radiation. However, Fukushima's radiation dose does not exceed 100 m㏜. Above 100 m㏜ is the number found in very serious radiation accidents. In environments above 100 m㏜, exposure doses and risks are proportional, so the risk of cancer increases daily.

However, the spatial radiation dose just in front of Fukushima Station is 0.14 μSv / h as of August 21, 2019. This is microsievert units. In milliseconds, it's 0.00014m / h. It is lower than this near the Azuma baseball field. Of course, at some points, 0.5 μSv / h can be found, as measured by the local media. At the same time, Seoul yields 0.118 μSv / h. This is 0.000118 m㏜ / h. The dose-to-hazard ratio is more than 100 m㏜, and the spatial radiation dose between Seoul and Fukushima is around 0.0001 m㏜ / h. In other words, if you stay in Fukushima for one week, the amount of exposure is 0.023m㏜, which is similar to that of one week in Seoul, but this is not exactly known about the relationship between exposure and health.

In other words, it is unconfirmed that a week in Fukushima reports that the risk of cancer increases every day. The LA Times quoted a professor from Johns Hopkins University. The professor has not yet proved to be at greater risk below 100m㏜. I asked by e-mail what the purpose was and I got an answer. As mentioned earlier, for radiation protection specialists, a model that assumes that risk is proportional to less than 100 m㏜ is best, and that statement was cited in the article. Minimizing radiation exposure is aided by the public's fear of it and media coverage that reflects that fear.

● Should I get less than 0.1m?

Yes. So you can decide you don't want to go to Fukushima. However, those who have made such a decision should also refer to the following figures. According to the Finnish Radiation Protection Agency data, when flying 10 km on an airplane, you are exposed to 5 μSv of radiation per hour. This is 10 times the number measured by the domestic media in front of the Fukushima Azuma Baseball Stadium. If you have an abnormality in your health and take a chest X-ray, you get 0.1m㏜, which is 100μSv, so it's like staying 200 hours only at the point where 0.5 is located in front of Azuma Ballpark.

In Korea, the amount of spatial radiation is different because the ground of each region is different. Based on the August 21, 2019, the annual radiation dose is calculated to be 1.62m㏜ per year in Sokcho, Gangwon-do and 0.65m㏜ per year in Seogwipo, Jeju. When you live a year, Sokcho residents receive about 1m of radiation more than Seogwipo residents. That does not mean that the media reports that Sokcho residents are in danger. In addition, some areas of Finland have much higher radiation doses than Sokcho, exceeding 6m² a year, but our government does not consider travel bans. The effects of radiation on the human body, whether from Finnish nature or artificially emitted from Fukushima, are the same.