Sunday, July 3, 2011

Radiation levels of 0.15 uSv/hr in rainwater drainage pit in our home in Totsuka!

I almost ignored taking soil radiation readings after few initial random readings I took in front of our home in Totsuka which showed no elevated readings (compared to the normal time readings published by the MEXT). However, today, I took the reading of soil and other debris accumulated in the rainwater drainage pit in our home and I am surprised!

I am taken by surprise since the radiation readings in the rainwater drainage pit recorded a radiation dose rate of 0.15 uSv/hr (beta+gamma) which is roughly double the background radiation in this area (I am comparing with the normal time background radiation only because that are the only values I have to compare with normal time though I understand that both are not the same).

The ambient radiation levels recorded away from this point is 0.1 uSv/hr.

All these days, I was in the opinion that we are relatively safe from soil contamination since we are away from Fukushima. No, we are not! Our soil is contaminated....the reason that I could record in this pit is because it accumulates the runoff from the roof.

Explanation on why I said it is elevated: I think I should clarify what I mean by elevated levels. This is first highest value I have recorded to date in our location! The soil readings I recorded about a month ago was 0.09 uSv/h in front of our home; the indoor reading yesterday was 0.1 uSv/hr, background radiation at 10 feet away from this drain was 0.1 uSv/hr. So, I was talking in relative terms.

I agree that this reading is nothing in comparison to what people have been reporting from elsewhere. However, reading an 'elevated/higher level' at one spot than other spots in the same location does qualify it to be contaminated, warranting precaution, isn't it?

The immediate decision to be implemented is:
  • not allowing my kid playing outside without attending to him,
  • to be cautious while cleaning the home, especially the dusty areas include air vents, door panels and screens,
  • cautious, cautious, and cautious. 


Higher radiation dose rate readings recorded in the rainfall drainage pit in our home in Totsuka, Yokohama

28 comments:

pep said...

0.15 USV / h high? you have no idea.

Teja said...

Is this radiation level is safe? I stay in Atsugi, Kanagawa prefecture!
Please let me know, how safe it is and food safety in Kanagawa prefecture. Thank you.

Anonymous said...

Average levels in Nerima-ku, Tokyo, have been 0.08 to 0.12, but I have also found places that are 0.32.

By comparison, I have seen readings in Kashiwa, Chiba, that range from 2.37 to over 4.0... now that's dangerous.

Prabhakar SVRK said...

Pep: elevated radiation levels mean higher than what I have seen at our home so far. It has nothing to do with other higher radiation levels found at other places. If you have read the blog post, you would see that I have also recorded 0.09 uSv/hr readings from soil which was at the same level of normal time background radiation readings published by MEXT. Now, when a spot in your home shows higher radiation than other spots, it does warrant a notice for special care. That is why, I am suggesting my wife to be careful when she cleans/dusts home, wearing some kind of masks. Hope it clarifies.

Prabhakar SVRK said...

Teja:

I am not a radiologist but just one of you who is trying to make sense out of this situation. We all are at best good about measuring and reporting radiation levels but when it comes to health impacts, none of us even close to a crack doctors.

As far as my understanding goes, no amount of radiation exposure is good for health since there is no conclusive medical research available that correlates between amount of radiation levels and associated health impacts (It may be available but I havent come across so far).

There are two things that we need to distinguish, one is external exposure and the other is internal exposure (i.e. through ingestion of radioactive substances). Now, there are broad scales published by MEXT (you can find them on my blog) that shows what category of people are allowed to expose to what levels of radiation, but it doesnt say what would be associated health affects.

We also need to be aware that internal exposure of radiation is much more dangerous than external exposure, (I guess it is especially the case with alpha emitters which often do not harm much when they are outside since they are least penetrating). However, when any radioactive substance is ingested, in any minute quantities, it continues to emit radiation and damage cells around it. There is no way one can detect such minute quantities and remove it from the body. We dont know how much substance can enter body without causing negative effects, there is no information available about it, at least I havent seen it.

I also learned from discussions in various groups that radiation exposure effects are cumulative.

So, for these reasons, I concluded that maximum precaution is of paramount importance.

Now, some may ridicule about radiation levels posted by me saying they are not harmful. I tend to question it for the reason that any contaminated environment can pose threat may not be due to external exposure but due to the possibilities of entering these substances into our body. Consider situations like one of our house members cleaning these areas without wearing a mask or children playing in dust and putting their fingers in their mouth. Now, since we dont have any information on safety of these situations, the precaution principle tells me that I should take maximum measures possible rather than to repent later. The reason that these spots/areas are showing higher readings than other areas tells me that they are contaminated and I should avoid them for obvious reasons. I wouldnt get into the debate of what level of radiation contamination is OK since the information is not available. Why would we want to be complacent about something that is not based on sound information? I will not gamble.

I hope it make sense. Please consider that these are only my views and they are in no way tested or otherwise (and we don`t need to test them too since stakes are too high to gamble).

My message is, take maximum precaution so that you dont have to repent later.

Teja said...

Hi Prabhakar garu, thank you very much for good explanation!!!I am a Ph.d student in Wind Engineering field and staying in Atsugi. We are afraid of buying of vegetables from super markets also. We dont know the available vegetables are radiation free or not. But, the local people are buying like as usual. Anyway thank you very much for your explanation.

Prabhakar SVRK said...

Dear Teja, we are not buying anything produced within the Kanto and tohoku regions (that would exclude upper half of Japan excluding Hokkaido). I would say it is our preference. I cannot suggest for you for the reason that I have no valid reason why we are doing what we are doing, other than that most of it is because of the fear and taking decisions in fear is not the best way to do.

I can only say that don't be too much worried about the environmental radiation exposure than about the food you take. You would want to write down the Kanji of all prefectures in Kanto and Tohoku region (about 13 of them) and check on the packets you buy, most of them are labelled. I am sure you can buy Onions, potatoes, some brinjal, bananas, some water melons, milk from Hokkaido (not the yogurt, since yogurt is made from mixed milk from all places), bhendi etc. If you have a store like Costco, it can extend your selection a bit mostly on fruits front. Then, see what is your nutrition from these and try to re-think the strategy.

Hope it helps.

Teja said...

Prabhakar garu, thank you very much for your suggestions. I really worried very much and i am not buying any vegetables from Japan for the past 3 months. Just i am buying some pumpkin, potato from Australia and France. Now i will try to buy as you suggested. Thank you very much.
Teja.

Anonymous said...

why not...

Mahesh said...

Prabhakarji, can you pl. send kanji charaters of these 13 place of kanto and tohoku area.
Thanks.
Mahesh

Prabhakar SVRK said...

Hi Mahesh, the kanji are

Kanto region (関東) (8 prefectures)
Chiba 千葉県
Gunma 群馬県
Ibaraki 茨城県
Kanagawa 神奈川県
Saitama 埼玉県
Tochigi 栃木県
Tokyo 東京

Tohoku region (東北) (6 prefectures0
Akita 秋田県
Aomori 青森県
Fukushima 福島県
Iwate 岩手県
Miyagi 宮城県
Yamagata 山形県

Mahesh said...

Thank you very much

Anonymous said...

Hello,
I shashikant living in Atsugi city,
is it safe to bring my 7 month old child here.??
what is u r opinion, i enquired here local but in hon atsugi area they r saying is safe.

Prabhakar SVRK said...

Hi Shashikant, Atsugi is more or less same as the place we live in, Totsuka. Few things for you to take care of, water from outside this region (usually bottled water), milk only from Hokkaido, I wouldnt suggest you buying milk cubes in Japan yet for the same reason as that of not buying any milk from this part of japan, be careful with the vegetables. We have been avoiding vegetables/milk from Tohoku, Kanto, and northern Chubu regions. That leaves you with Hokkaido and southern Japan for your daily subsistence. We are already feeling that my son is not having sufficient green leafy vegetables that are important at any stage of life and more so for kids; since most of leafy vegs in our area are coming from Tohoku/Kanto regions. So, decide accordingly. If you can manage, why bring him?

Teja said...

Hello sir Prabhakar garu, How are you? Now-a-days we didnt find any information from your side like before! Are you in Japan or in India now?
Please let me know about the food contamination and other things. Thank you very much for your information.

Teja.

Prabhakar SVRK said...

Hi Teja, thanks for writing, actually I am busy with work these days, I think I would not have time to do that for some more days/weeks. Hope things are fine at your end.

Teja said...

Hi Prabhakar garu, Thanks for your reply. Everything is fine i feel. How is the food contamination now in Kanagawa region. Just i am buying the vegetables except from Kanto and thohaku regions. I stopped drinking milk and curd also.Even fruits also not buying now a days. Please let me know some information regarding this.

Thanks for your information
Teja.

Anonymous said...

Hi Prabhakar garu..Good evening!
Did you read about the news "High radioactivity measured at Tokyo school"?? Is this safe??

Regards
Teja

Prabhakar SVRK said...

Hi Teja, I read about it in some online news but didnt care much since there are several news coming these days. On the other day, authorities have found high radiation levels from basement of some apartment where contaminated bottles were stored.

How safe it is? The answer is not all that simple as I understand. It depends how you are exposed to it, things like how long, whether that contamination has entered into your body etc. However, just consider this. If there are several ditches around that accumulates rainwater runoff, when they dry and wind blows, the radiation does enter into air through dust and enter into our body even if you think you are not directly in contact with those areas. Same is the case at our home. We are strictly monitoring where our son is going and how is playing around our home. It is strictly no for him to play with soil of any type. Having said that, we had to let him attend a tuber digging exercise by his kindergarten somewhere near our home under supervision of my wife. We brought samples of those soil and tested to make sure that he is not exposed to something surprise.

Somebody who have been working on radiation safety in US told me that radiation exposure is like cumulative, all exposures can be considered cumulative in their impact on our health. My principle is, avoid any kind of exposure of any duration. If you are living in areas like Chiba/Ibaraki, I would strongly suggest wearing a mask on regular basis.

Anonymous said...

Hi Prabhakar garu, thank you for your information! I am living in ATSUGI. I have to be here 1.5 years more from now! Our area no one is caring about the situation. I am not using any mask, i was using in april and may, then i stopped using. Do you know any precaution we have to take like taking some ayurvedic medicines to improve our immune system to fight with this kind of radio active particles entered into body. Do you use anything like this?

Thanks for your most valuable information.

Teja.

Prabhakar SVRK said...

Hi Teja, I am sorry, I have no idea about it. If your time permits, I would suggest you to call your family doctor back in India or ask one of your family members to consult a radiologist and seek advise. That is the best way to do. Five months ago, we did the same thing and the radiologist suggested to either refrain from sending children to Japan or to observe strict regulation on the type of food taken (in terms of from where it is coming etc).

Anonymous said...

Hi Prabhakar garu,
Thanks for your advice. I am going to India during December 2012. I will consult that time. As per the recent news that, in Tokyo also there is heavy radiation levels. Based on this, even kanagawa prefecture also may have same levels right?? I am staying in Atsugi, Kanagawa prefecture.

Thanks for your advise.
Teja

Anonymous said...

Hi Prabhakaru garu,

How are you sir, now a days i havent seen your postings. Where are you living sir now? Please let me know the situation now!!

Thank you
Teja

Prabhakar SVRK said...

Hi Teja,

Sorry, I have been busy with the work and couldnt spend much time on radiation thing. We are still in Yokohama. As for radiation levels, there are two things we need to talk about. Ambient radiation levels and the contamination of food. My readings suggest that the ambient radiation levels are nowhere near to cause health hazard. However, the contamination of food and accumulation of radiation substances in the body is still possible if food from this region is consumed. That is the reason why I suggested you to avoid food coming from Kanto region as well.

Anonymous said...

Hi Prabhakar garu,

How are you? How are the things are going on now? Many news are coming now that tokyo also contaminated!! I dont know the fact in this news! Plz let me know the status if you know.. sorry for disturbing you....

Thank you
Teja.

Prabhakar SVRK said...

Hello Teja,

Yes, we have been discussing this situation for long enough for now, the reason why we have been avoiding any food coming from Kanagawa and Kanto region. If you refer to my earlier responses, you would see that I have been suggesting to avoid a whole lot of northern Japan for consuming any food from these areas. Please refer to this map published in Geophys. Res. Lett that Min of health and labor has shared: http://www.mhlw.go.jp/stf/houdou/2r9852000001nif2-att/2r9852000001niv3.pdf.

The original paper based on simulation studies can be seen here: http://www.nies.go.jp/shinsai/Merge-2011GL048689-pip.pdf.

Please refer to the table s1 in the paper that tells that there is significant difference in Cs deposition between Kanagawa and Tokyo areas. Though these are only simulation results, the authors suggest that these are in line with the actual observed records. Please take a note of all 16 prefectures listed in the paper.

Morino, Y., T. Ohara, and M. Nishizawa: atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011, Geophys. Res. Lett., doi:10.1029/2011GL048689, in press. (http://www.nies.go.jp/shinsai/Merge-2011GL048689-pip.pdf から取得可能)

Anonymous said...

Hi Prabhakar garu,

Thanks for your detailed description!! I will be in contact with you.

Thankyou very much
Teja

Anonymous said...

Hi Prabhakar garu,
Good morning.
After a long time..How are you and your work? Now how is the situation in kanagawa area and Tokyo area? Thanks for your valuable information.

Teja.