Tokyo radiation levels – daily updates
Dear all,
As this page became too long I started a new one for April Tokyo radiation levels updates. To visit the page please click here.
Update (1st of April 10:37 – Tokyo Time):
31st of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 3.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.14
18:00 0.13
19:00 0.13
20:00 0.13
21:00 0.14
22:00 0.13
23:00 0.15
Update (1st of April 00:10 – Tokyo Time):
The latest graph for the Tokyo radiation levels (20th – 31st of March):
Update (31st of March 18:30 – Tokyo Time):
31st of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 3.5-4 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.13
10:00 0.14
11:00 0.15
12:00 0.14
13:00 0.15
14:00 0.15
15:00 0.14
16:00 0 14
17:00 0 14
Update (31st of March 13:18 – Tokyo Time):
31st of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo Tokyo time) Radiation Levels up to 3.5-4 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.15
1:00 0.15
2:00 0.13
3:00 0.14
4:00 0.16
5:00 0.14
6:00 0.15
7:00 0.15
8:00 0.15
9:00 0.13
Update (31st of March 13:15 – Tokyo Time):
30th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 3.5-4 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.14
18:00 0.15
19:00 0.15
20:00 0.16
21:00 0.15
22:00 0.14
23:00 0.15
Update (30th of March 20:28 – Tokyo Time):
Here is the latest graph with the data for 30th of March included.
As expected 7-8 days after the pick from 22nd-23td of March the radiation levels are almost twice less (the half life of Iodine-131 is 8 days).
Update (30th of March 20:28 – Tokyo Time):
30th of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 3.5-4 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.16
10:00 0.15
11:00 0.15
12:00 0.16
13:00 0.15
14:00 0.16
15:00 0.15
16:00 0.15
17:00 0.14
Update (30th of March 9:44 – Tokyo Time):
30th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo a.m. Tokyo time) Radiation Levels up to 3.5-4.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.16
1:00 0.15
2:00 0.15
3:00 0.17
4:00 0.14
5:00 0.14
6:00 0.15
7:00 0.16
8:00 0.18
9:00 0.16
Update (30th of March 9:40 – Tokyo Time):
29th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 4-4.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.18
18:00 0.17
19:00 0.16
20:00 0.18
21:00 0.15
22:00 0.16
23:00 0.16
Update (29th of March 20:55 – Tokyo Time):
The latest graph:
Update (29th of March 20:39 – Tokyo Time):
29th of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo a.m. Tokyo time) Radiation Levels up to 4.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.19
10:00 0.17
11:00 0.17
12:00 0.18
13:00 0.18
14:00 0.18
15:00 0.17
16:00 0.17
17:00 0.18
Update (29th of March 9:51 – Tokyo Time):
29th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo a.m. Tokyo time) Radiation Levels up to 4 – 5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.19
1:00 0.17
2:00 0.16
3:00 0.17
4:00 0.16
5:00 0.18
6:00 0.18
7:00 0.17
8:00 0 17
9:00 0.19
Update (29th of March 9:47 – Tokyo Time):
28th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 4 – 5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.18
18:00 0.19
19:00 0.19
20:00 0.17
21:00 0.17
22:00 0.17
23:00 0.18
Update (28th of March 22:07 – Tokyo Time):
Just added the data for 28th of March (till 17:00) on the graph:
Update (28th of March 18:10 – Tokyo Time):
28th of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 4.5 – 5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.18
10:00 0.19
11:00 0.18
12:00 0.20
13:00 0.19
14:00 0.19
15:00 0.20
16:00 0.18
17:00 0.18
I will update the graphic a little bit later.
Update (28th of March 9:49 – Tokyo Time):
28th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo a.m. Tokyo time) Radiation Levels up to 4.5 – 5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.19
1:00 0.17
2:00 0.18
3:00 0.18
4:00 0.20
5:00 0.19
6:00 0.20
7:00 0.18
8:00 0.18
9:00 0 18
Update (28th of March 9:44 – Tokyo Time):
27th of March 2011 hourly Tokyo radiation measurements (12:00 – 23:oo Tokyo time) Radiation Levels up to 4.5 – 5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
12:00 0.19
13:00 0.20
14:00 0.20
15:00 0.18
16:00 0.20
17:00 0.20
18:00 0.19
19:00 0.20
20:00 0.20
21:00 0 19
22:00 0.20
23:00 0.20
Update (27th of March 13:40 – Tokyo Time):
Here is the latest graph:
It looks like we are observing the natural decay of iodine-131 (half-life 8 days). If this is correct radiation levels half the peak of 22nd-23rd of March must be reached around 30th of March. It is also important to see if there will be a new rise in the radiation levels in Tokyo after next rain.
Update (27th of March 13:05 – Tokyo Time):
27th of March 2011 hourly Tokyo radiation measurements (00:00 – 12:oo Tokyo time) Radiation Levels up to 4.5 – 5.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.21
1:00 0.21
2:00 0.20
3:00 0.19
4:00 0.19
5:00 0.19
6:00 0.20
7:00 0.22
8:00 0.20
9:00 0 20
10:00 0.18
11:00 0.20
12:00 0.19
Update (27th of March 12:57 – Tokyo Time):
26th of March 2011 hourly Tokyo radiation measurements (12:00 – 23:oo Tokyo time) Radiation Levels up to 4.5 – 5.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
12:00 0.20
13:00 0.21
14:00 0.22
15:00 0.20
16:00 0.21
17:00 0.21
18:00 0.23
19:00 0.20
20:00 0.18
21:00 0.20
22:00 0.20
23:00 0.20
Update (26th of March 16:22 – Tokyo Time):
Here is the latest graph (20th – 26th of March):
It looks like the radiation level is slowly going down.
Update (26th of March 14:12 – Tokyo Time):
26th of March 2011 hourly Tokyo radiation measurements (00:00 – 12:oo Tokyo time) Radiation Levels up to 5 – 6 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.22
1:00 0.23
2:00 0.21
3:00 0.20
4:00 0.22
5:00 0.23
6:00 0.22
7:00 0.21
8:00 0 21
9:00 0.23
10:00 0.23
11:00 0.22
12:00 0.20
I will update the graph a little bit later.
Update (26th of March 14:10 – Tokyo Time):
25th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 5.5 – 6 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.22
18:00 0.22
19:00 0.22
20:00 0.22
21:00 0.22
22:00 0.22
23:00 0.24
Update (25th of March 19:14 – Tokyo Time):
25th of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 5 – 6.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.24
10:00 0.26
11:00 0.25
12:00 0.25
13:00 0.22
14:00 0.24
15:00 0.21
16:00 0.21
17:00 0.22
Update (25th of March 10:11 – Tokyo Time):
Here is the latest graphic 20th – 25th (up to 9:00 a.m.):
Update (25th of March 9:41 – Tokyo Time):
25th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo Tokyo time) Radiation Levels up to 5.5 – 6 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.25
1:00 0.24
2:00 0.25
3:00 0.23
4:00 0.23
5:00 0.22
6:00 0.22
7:00 0.23
8:00 0 25
9:00 0.24
Update (25th of March 9:37 – Tokyo Time):
24th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 6 – 7 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.24
18:00 0.29
19:00 0.24
20:00 0.27
21:00 0.24
22:00 0.27
23:00 0.26
Update (24th of March 22:22 – Tokyo Time):
24th of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 6 – 7 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.25
10:00 0.26
11:00 0.24
12:00 0.27
13:00 0.23
14:00 0.24
15:00 0.24
16:00 0.29
17:00 0.24
Update (24th of March 10:11 a.m. – Tokyo Time):
Here is the graph for the last several days:
Update (24th of March 9:49 a.m. – Tokyo Time):
24th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo a.m. Tokyo time) Radiation Levels up to 6 – 7.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.30
1:00 0.26
2:00 0.26
3:00 0.27
4:00 0.26
5:00 0.26
6:00 0.28
7:00 0.25
8:00 0 23
9:00 0.25
Update (24th of March 9:45 a.m. – Tokyo Time):
23rd of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 6 – 7 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.24
18:00 0.26
19:00 0.24
20:00 0.25
21:00 0.28
22:00 0.28
23:00 0.29
Update (23rd of March 23:57 – Tokyo Time):
Dear All,
I received an answer from our radioprotective unit concerning my question for the presence of “hot particles” in Fukushima incident. Here is the main part of the text:
”
In case of atomic bomb explosion in the air and Chernobyl accident a huge amount of small pieces of nuclear material was spreaded in the air, and the fission product that is very radioactive is contained in them. They are "hot particles". In the present case of Fukushima station, however, most released radioactivity is iodine and cesium, which are the volatile elements, and no nuclear material was released. I think that it is not necessary to worry about the "hot particle" this time."
Update (23rd of March 20:14 – Tokyo Time):
23rd of March 2011 hourly Tokyo radiation measurements (9:00 – 17:oo Tokyo time) Radiation Levels up to 6.0 – 7.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.26
10:00 0.30
11:00 0.27
12:00 0.27
13:00 0.27
14:00 0.27
15:00 0.25
16:00 0.26
17:00 0.24
Update (23th of March 14:30 – Tokyo Time):
WARNING!
Radioactive iodine in Tap water in Tokyo exceeding limit for infants (Kyodo news agency)!!!
http://english.kyodonews.jp/news/2011/03/80399.html
Give to your kids only imported bottled water!!!!!!
Update (23th of March 10:10 a.m. – Tokyo Time):
23rd of March 2011 hourly Tokyo radiation measurements (00:00 – 9:oo a.m. Tokyo time) Radiation Levels up to 6.5 – 7.5 times above normal
Today around 1:00 the radiation level reached 0.30 μSv/h. There were no such high values since 16th of March!
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.28
1:00 0.30
2:00 0.29
3:00 0.29
4:00 0.28
5:00 0.29
6:00 0.28
7:00 0.27
8:00 0 26
Here is the graphical representation of the radiation levels for the last 3 days. Please notice that I had to change again the scale to 0.35 microSv/h (from 0.3 and 0.25 from the previous graphs).
Update (23th of March 10:03 a.m. – Tokyo Time):
22nd of March 2011 hourly Tokyo radiation measurements (17:00 – 23:oo Tokyo time) Radiation Levels up to 6.5 – 7 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.27
18:00 0.27
19:00 0.25
20:00 0.26
21:00 0.27
22:00 0.29
23:00 0.28
Update (22nd of March 9:53 a.m. – Tokyo Time):
22nd of March 2011 hourly Tokyo radiation measurements (9:00 a.m. – 17:oo Tokyo time) Radiation Levels up to 6 – 7 times above normal
It seems that now (after the rain) the radioactivity became embedded in the city and it stabilized around 0.24-0.27 μSv/h. If this speculation is correct we could expect return to values of 20 of March (around 0.1 μSv/h or only around 2.5 times above normal) in 1-2 if not 3 weeks (half life of iodine 131 is around 8 days).
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.26
10:00 0.27
11:00 0.23
12:00 0.26
13:00 0.24
14:00 0.25
15:00 0.26
16:00 0.24
17:00 0.27
Update (22nd of March 9:53 a.m. – Tokyo Time):
22nd of March 2011 hourly Tokyo radiation measurements (00:00 a.m. – 9:oo a.m. Tokyo time): – The Radiation Levels up to 6.5 – 7 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.25
1:00 0.25
2:00 0.27
3:00 0.27
4:00 0.26
5:00 0.27
6:00 0.25
7:00 0.23
8:00 0.25
9:00 0 26
Here is the graphical representation of data from 20th, 21dt and the morning of 22nd of March (please notice that I changed the scale of the graph from 0.25 to 0.3 microSv/hour in comparison with the previous graph (20-21st of March)):
Update (22nd of March 9:53 a.m. – Tokyo Time):
21st of March 2011 hourly Tokyo radiation measurements (12:00 p.m. – 23:oo p.m. Tokyo time): – The Radiation Levels 5 to 6.5 times above normal
Normal background radiation level: 0.04μSv/h
Time μSv/h
12:00 0.20
13:00 0.21
14:00 0.19
15:00 0.21
16:00 0.23
17:00 0.24
18:00 0.22
19:00 0.22
20:00 0.25
21:00 0 26
22:00 0.23
23:00 0.25
Update (21st of March 12:35 p.m. – Tokyo Time):
21st of March 2011 hourly Tokyo radiation measurements (00:00 p.m. – 12:oo a.m. Tokyo time): – The Radiation Levels Are Rising Again!!!
The radiation levels ARE RISING AGAIN. They were almost only 2.5 times above normal on 20th but today (21st) around 12:00 they are reaching 5 TIMES above normal!!!
May be it has something to do with the precipitation in Tokyo but I am not sure!
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.11
1:00 0.12
2:00 0.12
3:00 0.11
4:00 0.11
5:00 0.11
6:00 0.12
7:00 0.12
8:00 0.14
9:00 0 15
10:00 0.19
11:00 0.16
12:00 0.20
Here is the graph for the last 36 hours. You can see the up-regulation in the radiation level in the last 4-6 hours. Please notice that the scale of the graph is 0.25 microSv/hour:
Update (21th of March 12:30 p.m. – Tokyo Time):
20th of March 2011 hourly Tokyo radiation measurements (12:00 p.m. – 24:oo p.m. Tokyo time):
I will upload the data for 21st fro Tokyo in few minutes. The radiation levels ARE RISING AGAIN!!!
Normal background radiation level: 0.04μSv/h
Time μSv/h Time μSv/h
12:00 0.09
13:00 0.10
14:00 0.10
15:00 0.11
16:00 0.09
17:00 0.10
18:00 0.10
19:00 0.10
20:00 0.10
21:00 0 10
22:00 0.10
23:00 0.11
Update (20th of March 12:46 p.m. – Tokyo Time):
20th of March 2011 hourly Tokyo radiation measurements (00:00 – 12:oo a.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
0:00 0.11
1:00 0.09
2:00 0.10
3:00 0.11
4:00 0.11
5:00 0.10
6:00 0.10
7:00 0.10
8:00 0.10
9:00 0 10
10:00 0.10
11:00 0.10
12:00 0.09
Update (20th of March 12:36 p.m. – Tokyo Time):
19th of March 2011 hourly Tokyo radiation measurements (12:00 – 23:oo Tokyo time):
There is a small up-regulation around 15:00 but otherwise the tendency is clearly downward!
Normal background radiation level: 0.04μSv/h
Time μSv/h
12:00 0.11
13:00 0.11
14:00 0.11
15:00 0.13
16:00 0.11
17:00 0.11
18:00 0.11
19:00 0.10
20:00 0.09
21:00 0 11
22:00 0.11
23:00 0.10
Update (19th of March 2:03 p.m. – Tokyo Time):
19th of March 2011 hourly Tokyo radiation measurements (00:00 a.m. – 12:oo a.m. Tokyo time):
Slowly but the radiation levels are clearly going down! Only around 2.5 times above normal. I think the main risk now (if any) is from “hot particles” brought in Tokyo (or other cities) from people who have been in the contaminated area. I still do not have any reliable information for the presence of such particles though.
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.12
1:00 0.10
2:00 0.12
3:00 0.12
4:00 0.11
5:00 0.11
6:00 0.12
7:00 0.11
8:00 0 11
9:00 0.11
10:00 0.11
11:00 0.12
12:00 0.11
Update (19th of March 1:58 p.m. – Tokyo Time):
18th of March 2011 hourly Tokyo radiation measurements (17:00 p.m. – 23:00 p.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.12
18:00 0.11
19:00 0.11
20:00 0.12
21:00 0.12
22:00 0.11
23:00 0.10
Update (18th of March 7:50 p.m. – Tokyo Time):
18th of March 2011 hourly Tokyo radiation measurements (9:00 a.m. – 17:00 p.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.11
10:00 0.12
11:00 0.13
12:00 0.12
13:00 0.12
14:00 0.11
15:00 0.13
16:00 0.11
17:00 0.12
Update (18th of March 10:37 a.m. – Tokyo Time):
18th of March 2011 hourly Tokyo radiation measurements (00:00 a.m. – 9:oo a.m. Tokyo time):
It seems that the background radiation level is decreasing. If the tendency is kept within several weeks we should have near normal levels (in Tokyo).
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.13
1:00 0.14
2:00 0.13
3:00 0.13
4:00 0.12
5:00 0.12
6:00 0.12
7:00 0.13
8:00 0 12
9:00 0.11
Update (18th of March 10:30 a.m. – Tokyo Time):
17th of March 2011 hourly Tokyo radiation measurements (17:00 p.m. – 23:oo p.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
Time μSv/h
17:00 0.13
18:00 0.14
19:00 0.14
20:00 0.13
21:00 0.13
22:00 0.13 5:00 0.12
23:00 0.13
Update (17th of March 23:10 – Tokyo Time):
I found the Ibaraki radiation level data (Ibaraki is just north-east of Tokyo) for 15-17th March. The pdf file is in Japanese but I think the table is self-explanatory.
At average the radiation levels in Ibaraki are 5 to 10 times higher than in Tokyo. I found the pdf file at this website (in Japanese). I am sorry I have no time to translate right now but you can use google translate eventually.
Update (17th of March 19:33 – Tokyo Time):
17th of March 2011 hourly Tokyo radiation measurements (9:00 a.m. – 17:oo p.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
Time μSv/h
9:00 0.14
10:00 0.15
11:00 0.14
12:00 0.14
13:00 0.13
14:00 0.14
15:00 0.13
16:00 0.13
17:00 0.13
Apparently the radiation levels stabilized (for now) 3-4 times above normal.
Update (17th of March 11:08 – Tokyo Time):
I requested our main lab in Tokyo for information concerning the possible presence of “hot particles” in Tokyo area. I will post their answer immediately after I receive it!
Update (17th of March 10:50 – Tokyo Time):
17th of March 2011 hourly Tokyo radiation measurements (00:00 – 9:00 a.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
Time μSv/h
0:00 0.13
1:00 0.14
2:00 0.14
3:00 0.14
4:00 0.15
5:00 0.14
6:00 0.13
7:00 0.13
8:00 0.13
9:00 0.14
Radiation level still 3-4 times above normal.
Graphic representation of the data from 16th of March and 17th of March (morning) – no spikes!
Update (17th of March 10:35 – Tokyo Time):
16th of March 2011 hourly Tokyo radiation measurements (17:00 – 23:00 p.m. Tokyo time):
Normal background radiation level: 0.04μSv/h
16th March
Time μSv/h
17:00 0.15
18:00 0.14
19:00 0.15
20:00 0.14
21:00 0.13
22:00 0.12
23:00 0.14
The radiation level is only 3-4 times above normal. What worries me is that these are “static” data. They do not exclude the presence of “hot particles” – conglomerates of dust and radioactive isotopes (here is the Wikipedia article on hot particles). If you inhale of ingest such particles – the local dose your tissues and organs will receive will be much higher. At presence we do not have information for the presence of such particles in Tokyo and surroundings. Somebody must go in Tokyo with portable radiation detector and check for the presence of “hot particles” in the parks and gardens! I will try to request this from our main facility in Tokyo from where I am receiving all the data. In any case if you are in Tokyo – wear mask and wash well your hands every time you go out!!!
Update (16th of March 18:30):
16th of March 2011 hourly Tokyo radiation measurements (9:00 a.m. – 17:00 p.m. Tokyo time):
Normal background radiation level: 0.04 μSv/h
Time μSv/h
9:00 0.19
10:00 0.16
11:00 0.15
12:00 0.15
13:00 0.16
14:00 0.15
15:00 0.14
16:00 0.15
17:00 0.15
This time the radiations levels are only 3-4 times above normal. Let’s hope they stay at that level or lower.
Update (16th of March 14:04):
16th of March 2011 hourly Tokyo radiation measurements (1:00 – 9:00 a.m. ):
Normal background radiation level: 0.04 μSv/h
March 16
1:00 0.16 μSv/h
2:00 0.16 μSv/h
3:00 0.18 μSv/h
3:56 0.30 μSv/h
4:00 0.27 μSv/h
4:15 0.36 μSv/h
5:00 0.29 μSv/h
6:00 0.29 μSv/h
7:00 0.25 μSv/h
8:00 0.21 μSv/h
9:00 0.19 μSv/h
It seems now the radiation level in Tokyo is stably 4-7 times above normal!
Considering the explosions this morning in Fukushima nuclear plant I am afraid there could be a significant increase in the radiations level later during day (I hope I am wrong)! I will post the information immediately after I receive it.
Here is the graphical representation of the data for 15th of March and 16th of March morning (till 9:00 a.m.)
Update (16th of March 13:54):
The complete data for 15th of March 2011:
March 15March 15
3:00 0.04 μSv/h
6:00 0.12 μSv/h 9:00 0.17 μSv/h
10:37 1.62 μSv/h (highest reading for this period)
12:00 0.31 μSv/h
14:00 0.23 μSv/h
16:00 0.20 μSv/h
18:00 0.20 μSv/h
19:13 1.13 μSv/h (second pick)
20:00 0.24 μSv/h
22:00 0.16 μSv/h
24:00 0.16 μSv/h
Here they are for 15th of March:
Normal background radiation level: 0.04 μSv/h
March 15
3:00 0.04 μSv/h
6:00 0.12 μSv/h
9:00 0.17 μSv/h
10:37 1.62 μSv/h (highest reading for this period)
12:00 0.31 μSv/h
For comparison during X-ray Chest radiograph you are receiving 0.06 mSv and up to 20 mSv of during X-ray computed tomography.
Here is a graphical representation of the changes in radiation level (click on image to see the full version):
[...] Tokyo radiation levels 1 chottomatte.net — The exact radiation levels in Tokyo. I will try to make updates every day. [...]
Thank you so much for posting this information!! My parents live in Tokyo but I live in the US. It’s quite difficult to find any information on the radiation levels in the Tokyo area. Your hard work and updates are very much appreciated
Very helpful. Could you please publish an average reading for the day? With the selected data it is difficult to calculate an average from the figures, given the spikes.
Thank you Betty. I hope your parents are save in Tokyo. Still – if they do not have any important business there may be it will be better for them to leave .
Thank you.
I am sorry Lee but I do not have this exact information at the moment.
Thank you for your updates. i understand that the Japanese govt wants to hide information that can cause a city wide panic. However, this is essential information that the Japanese citizens have a right to know.
Wow, the background radiation level in Tokyo is really low…
Even at the peak value 1.62 uSv/h for a year only gives you a dose of 14.2mSv (assuming 100% absorption), I think that’s about the level you will get from a full body CT scan.
What university is this information comming from?
Come to think of it, maybe the best data to have would be for the “area under the curve”. Would that be possible? Good on you for providing this important service!
They come from RIKEN, WAKO campus.
I agree Lee but I am just receiving pdf files with the hourly data and the graph. I can contact the people who provide them but I am afraid that right now they are overloaded with all sort of other problems and most probably it will take some time before I receive an answer.
Great thanks for the information, please keep posting!!!
I have a question though.
“Normal background radiation” listed here:
http://en.wikipedia.org/wiki/Orders_of_magnitude_%28radiation%29#cite_note-ORNLtb-3
is 0.4 microSv/hour and not 0.04 as indicated on this page. Am I missing something?
Hi Alex,
Could you please tell me where exactly is written 0.4 microSv/hour (on the wikipedia page), If possible just copy and paste the entire sentence. I am sorry but I couldn’t find it.
Anyway as far as I know 0.04-0.03 microSv/hour is the the correct value for most of the sea level locations. Also I am receiving the information directly from one of the leading Japanese scientific institutions (RIKEN) so I don’t think they made a mistake.
Hi Chottom,
Unfortunately, there is different table there now when I go by the link that I posted earlier. Someone must have modified the table and it does not show exactly what I saw before.
However, if we look at the line three, it has 0.01mSv (milisieverts) for daily value of “Natural background radiation, including radon”, which yields
0.01mSv/24hrs=~0.0004mSv/hr=0.4microSv/hr if I my math is right.
I think the version of the table that I saw earlier can still be found there under “View history”. E.g. the version in “Latest revision as of 13:22, 18 March 2011″. I am sure the time is not Japan time there and it seems to me that this version is what I saw at the time of my original comment. You can try this maybe:
http://en.wikipedia.org/wiki/Orders_of_magnitude_(radiation)
and search for “Natural background radiation” in the table:
Level Duration Hourly Description
0.01 Daily 0.0004 Natural background radiation, including radon
Again, it does not matter so much, the main thing is that people get the information they need, thanks to you!
I believe both Alex and Chottom are correct. Here is the link to the Wikipedia article on background radiation, citing a worldwide average of 2.4 mSv per year (or 0.27 microSv/hr) from a United Nations report. The report indicates a range of 1-10 mSv per year (or 0.11-1.14 microSv/hr) of background radiation, depending on location and other factors.
Wikipedia link- http://en.wikipedia.org/wiki/Background_radiation
United Nations report- http://www.unscear.org/docs/reports/gareport.pdf
Thank you for spending time to do this, Chottom.
Thank you very much for keeping us posted on the Tokyo radiation levels. Does this monitoring include all the different types of radiation? What are the levels that are dangerous to health?
Thank you Mike,
You first question – as far as I know this includes all the radiation. The main sources of radiation are iodine and cesium.
Your second question – this is what I found:
http://www.lbl.gov/abc/wallchart/chapters/appendix/appendixf.html
Notice (from the above source):
I think that in prefectures/areas where several to tenths of millisieverts per hour were measured (and please correct me if I am wrong but there were such areas well outside the 20 km evacuation zone) the people will receive doses close to millisievert (if not more) over the first several days or weeks. So in these prefectures most probably there will be at least several excess cancer deaths (most probably thyroid cancer deaths ) per 100 000 people during the next years.
Please notice that in the referred article there is no broad consensus on the effect of low doses of radiation.
PS. It seems that in central Tokyo it is rather safe.
PS. Please be cautious with my conclusions. Even though I have an MD and PhD in biological sciences I am not specialist in the field!
[...] radiation levels are still relatively [...]
Why do you have access to a radiation monitering station in Saitama?
The organization I am working for has a campus there with specialized radioprotection unit. They are updating us every day (2-3 times per day).
Thank you.
Peace.
Thank you for posting this short, factual information. We must layover in Tokyo in a few days and it is appreciated. The lack of bantering and uninformed opinions is especially noteworthy. Just facts and simple explanations. Well done.
Thank you jumpAmonkey.
The kyodo news agency information for the radioactive iodine contamination of Tokyo tap water just arrived.
We are in Kobe but we stocked with mineral water also just in case. My wife and kids are leaving on 31st of March for Europe. Good luck to you and your people.
I think a few rachets down the sensational ladder would do us all a favor. Writing ‘Warning!’ in red three times as a banner isn’t needed, being intelligent experienced adults we’ll get the ‘jist’ with one. Also, you don’t seem to mention that Tokyo has a third of the world’s average BGR. Your blog is interesting, but please, keep it on an keel that sails through the danger easily. Thanks
Hi Daisuke,
We have 2 little kids and maybe this makes me overreact a bit. Anyway – I removed two of the warnings and I will just let the rest go down as I am adding new updates. BTW what does BGR stand for?
Background Radiation. I too have children. A five year olf girl and an infant. If we keep level we’ll win through. Why haven’t you got out of the Kanto region, if you’re there, yet?
We are in Kansai, Kobe. The biggest danger here is from contaminated drinks and food if they reach the food distribution network. Anyway my wife and kids are leaving for Europe next week for at least a month. I will stay here as long as possible.
Hi,
Really useful data, great job!
I think that it would help people to put some things in context:
flying in a (high altitude i.e. long distance) aeroplane exposes you to about 10microSv/Hour [1]
Adding up all the hourly readings on here so far suggests that Tokyo residents have been exposed to about an extra 30microSv because of the crisis. That is equivalent to 3 hours on an aeroplane…
In other words If you had jumped on a flight to Europe (6-8 hours) on the 14th of March then you would have been exposed to more than twice as much radiation than if you had stayed in Tokyo.
[1]http://www.deq.idaho.gov/inl_oversight/radiation/overview.cfm
Thanks a lot for the information, and updating us on the hot particle issue.
Indeed, the biggest worry is ingesting radioactive materials into your body, as opposed to the radiation level itself. Iodine 131 has a half-life of 8 days in the atmosphere, but once in a human body it has a biological half-life of 120 days. This means unlike typical background radioactivity, Iodine 131 can accumulate in one’s body, specifically in the thyroid gland.
Also, I am guessing the limit for iodine in drinking water was probably set under the assumption that drinking water is your only exposure to radioactive iodine. Now, if we are both breathing in and drinking Iodine, shouldn’t that be accounted for?
Iodine amounts in the air on Mar 20 in Tokyo was 50 megabecquerel / “square” kilometer (50 becquere/ cubic meter).
Lastly, I wanted to point out that the US standard for Iodine in drinking water is only 4Bq/L (as opposed to the 300 Bq/L in Japan). I hope U.S. standards are just super conservative.
(http://www.atsdr.cdc.gov/csem/iodine/standards_regulations.html)
Not trying to cause a panic, but just thought i should ask the question, so someone more knowledgeable can weigh in.
Thank you for updating us with informative and objective data. I’m from Europe and have to go to Tokyo in 3 weeks (business trip). I hope the iodine will have decayed by then.
>Update (23rd of March 23:57 – Tokyo Time):
>Dear All,
>I received an answer from our radioprotective unit concerning my question for the presence of “hot >particles” in Fukushima incident. Here is the main part of the text:
>”
>In case of atomic bomb explosion in the air and Chernobyl accident a huge
>amount of small pieces of nuclear material was spreaded in the air, and the
>fission product that is very radioactive is contained in them. They are “hot
>particles”. In the present case of Fukushima station, however, most released
>radioactivity is iodine and cesium, which are the volatile elements, and no
>nuclear material was released. I think that it is not necessary to worry
>about the “hot particle” this time.”
>
Actually, the Safety Agency didn’t say much about it. They might have already detected some “hot particles”, or else, they didn’t even do the test for them. But I would rather think that it’s just that they haven’t told us about what they found.
I hope I’m wrong and you could find something that can give us some relief.
From Japan.
Hi AJ,
Thank you.
I agree with you but as JC mentioned the nature of the radioactive source is also important. In the airplane the additional radiation will be most probably due to cosmic radiation. But in our case we are dealing with radioactive iodine and cesium. The first one (again as JC mentioned) has a tendency to selectively accumulate in the thyroid gland. That is why even if the overall background radiation is only slightly elevated over the time you may receive significantly higher local dose inside your thyroid as a result of the iodine accumulation.
That is why the discrepancy between the Japanese (300 Bq/L) and US (4Bq/) standard (pointed out by JC) for radioactive iodine in drinking water is somewhat worried.
I will try to find more information on the issue.
All the best.
The worldwide average background dose for a human being is about 2.4 millisievert (mSv) per year, according to
http://en.wikipedia.org/wiki/Background_radiation
http://www.unscear.org/docs/reports/gareport.pdf
which is 2400 microSv/year=2400/(24×365)=100/365=0.27microSv/hour
Of course, if you have this much in the air, you do not want to add any more (e.g. from food or water) but if you don’t then is Tokyo levels really above “normal” now?
how can i post a graph on here its an interesting representation of your data
Thank you JC.
I found that the World Health Organization (WHO) recommends 10 Bq/l for radioactive Iodine – 131 as “Guidance levels for radionuclides in drinking-water”.
http://www.who.int/water_sanitation_health/dwq/fulltext.pdf page 203, table 9.3
But notice the explanations for (I think they are important) page 202 :
I think that here is all the information we need but I will need some time to decode it. (It seems though that within 1 year after nuclear incident the standards may differ)
Hi Simon
If you generated the graph you can send it to me to chottomattenet@gmail.com and I will eventually post it.
Or you can upload it to another server and post a link here.
JC I think I found the reason for the discrepancy between your 4Bq/L and the 100 Bq/L from the Japanese source.
4 Bq/L from your link is Environmental Protection Standards. So you should not use source with higher than 4 Bq/L Iodine-131 radiation for tap water (in long term or in general).
On the other hand in case of emergency situation the limit at which you must take preventive measures is indeed 100 Bq/L (or 0.1 kBq/kg) as it is given in the official document of INTERNATIONAL ATOMIC ENERGY AGENCY, Safety standards – page 289, Table V-I :
http://www-pub.iaea.org/MTCD/publications/PDF/ss-115-web/Pub996_web-5.
Here is a link to the top directory of the document:
http://www-pub.iaea.org/MTCD/publications/PDF/ss-115-web/Start.pdf
So I think the Japanese were right to act at the 100 Bq/L threshold of Iodine-131 radiation level.
Still I don’t know why they choose 300 Bq/L for adults – in the original document there is not such recommendation – as far as I understand it is 100 Bq/L for everybody in case of emergency.
Also it should be underlined that the levels must reach values bellow 10 Bq/L (World Health Organization) or 4 Bq/L (US – standard) for Iodine-131 radiation in long term if the tap water is to be be considered safe.
Again I do not have precise definition for long term.
For now though the situation with the tap water seems to be OK.
Food for thought:
http://ukinjapan.fco.gov.uk/en/news/?view=News&id=566811882
Hello, your radiation data are totally different than the ones I check in this Japanese website with Shinjuku measures: http://113.35.73.180/report/report_table.do
Hi, Keep up the monitoring.
There is another live geiger in Ebisu Tokyo, but mostly shows normal levels of background radiation with the odd spike. I guess it really goes up when it rains. http://www.alttokyo.com/tokyo-radiation-2/
Hi Victor and George.
I really don’t know what is the reason for such big discrepancy. I presume differences in the equipment, methods of measurement (for example its position – indoor vs outdoor) etc.
Anyway the people who distribute these data are working in the radiation protection unit of one of the leading Japanese (and world) scientific organizations so I rather trust them (at least to be precise with the values they send).
Thanks Chottom, for the digging up the information on safe iodine levels in drinking water. I guess let’s hope the level comes down to under 10 Bq/L.
This is what i received form the Canadian Nuclear Safety Commission:
“Thank you for contacting us. At this point there is no indication that there is any radiation health risk to Canadians outside the evacuation zones established by the Japanese authorities. Given the evolving situation, Canadians located within 80 km of the Fukushima Nuclear Power Plant should consider, as a further precautionary measure, evacuating this area. The directions of the Japanese government and local emergency response personnel should also be followed by all Canadians in Japan.
In establishing standards and recommendations, nuclear safety and health agencies take into consideration all pathways (air, food, water, etc) and susbtances. Japan has set provisionary limits which have permitted higher concentrations of radionuclides. These levels are consistent with those recommended by the International Atomic Energy Agency (IAEA) for emergency conditions. There is no immediate health risk.
For more information, I invite you to consult DFAIT’s web site on a regular basis: http://www.voyage.gc.ca/countries_pays/issues_enjeux/article-eng.asp?id=1106. “
Thank you for the information JC.
My personal opinion is that for now in Tokyo is safe. The only danger (not only in Tokyo but in general in Japan) is of contaminated food coming from the more seriously affected areas and spreading thorough the food distribution network.
I hope the Japanese government implements a very strict radiation monitoring control of food products!
Read. Think. Act.
http://www.largeassociates.com/3195%20Fukushima/R3195-A2.pdf
Thanks for making these updates available chottom. I check this website several times per day.
Incidentally, your results correlate strongly with the “Radioactive material level of fallout in Tokyo/day” available here:
http://ftp.jaist.ac.jp/pub/emergency/monitoring.tokyo-eiken.go.jp/monitoring/f-past_data.html
There was a spike in fallout per m^2 on 03/21~03/22, which matches your uSv/hr results.
Thank you chickkun.
The pick apparently is the result of a rain bringing down all the radioactive particles and embedding them in the soil and buildings of Tokyo. It is important to see if there will be similar pick after every rain.
Seems like your results differ from this source:
http://www.denphone.com/denphone-tokyo-office-geiger-counter
Seems the above source’s results are almost 2 times greater than yours.
I wonder what the reason could be for the difference?
@Soty
the results from your page differs because they are 2 weeks old
check the date again when there made :p
[...] I’ve recently corrected a few things on the chart (the old version is available here). In particular, I’ve changed the mammogram dose from 3 mSv to 0.4 mSv, based on figures from this paper. The other figures seem to hold up, and I’ve made only small corrections elsewhere. I’ve added a few more Fukushima-related doses where I could find data, but they’re examples only—not full coverage of the effects. Specifically, I added total exposure figures over the weeks following the accident for Tokyo, a typical spot in the Exclusion Zone, and a station place on the northwest edge of the zone that got a particularly heavy dose. Those data came from here (Google cache of now-dead MEXT page) and here. [...]
I just want to know if the tap water in Tokyo is completely safe for drinking now. I could still find many people buying water for drinking. Please reply to my querry.
Hi Neelam,
As far as I know the tap water in Tokyo is completely safe now.
Best
Hello,
Thanks for providing daily updates, it is really helpful.
I have a query regarding the food contamination.
Recently there are news about higher than permissible level of radiation found in Tea leaves in areas as far as Shizuoka.
However I am not sure, if radiation is found in tea leaves, why it is not found in other plantations or leafy vegetables
Also, what is he process of radiation check in food followed by the administrative office?
How can one be assured there is no food contamination.
Kindly let us know if you have some updates.
thanks a lot and regards
Thank you Sam,
Unfortunately I do not know what are exactly the procedures for food radiation control in Japan. The only thing I can say is – that we bought dosimeter on our own and we are checking from time to time some fresh food products (vegetables and others) and we didn’t find any abnormalities yet.
Hi Chottom,
Thanks for your reply, its just a bit of a relief !?
Are those samples tested by you come from the kanto area like Ibaraki, Tochigi, Saitama, Kanagawa etc?
Best Regards !
Hi Sam,
We just tested a few fresh vegetables and a few fish products from local shops.
We didn’t check their origin – just cared if they are fresh or not.
But our sampling is not representative in anyway. Actually recently we almost completely stopped using the dosimeter (after finding nothing suspicious).
I presume if we have to travel to Tokyo this summer we’ll use it again more often there.
I am sorry I can not give you more informative answer.
HI CHOTTOM,
Hou dangerous is in tokyo now?My family including 2 kids are going to stay in tokyo.Is radiation effect to my children?I am so worry,please suggest.and when will be the radiatin level normal.
Dear avas,
As far as I know it is safe in Tokyo now. Me and my family were in Tokyo Disney Land just a week ago. The radiation reading updates just show that the radiation levels in Tokyo still didn’t reach before Fukushima levels but there are many cities round the world with even higher natural background radiation levels.
Please notice that I am not a specialist in nuclear protection and this is just my personal opinion (I have some background in biomedical reasearch though).
I hope this helps.
All the best
hi chottom
i am observing your data everyday . IT is not seeing any changes for few months.Iam so worry about it.Do you have any idea the radiation level will ever nornal in tokyo?please suggest.
hi chottom
i am observing your data everyday . IT is not seeing any changes for few months.Iam so worry about it
Hi,
where is your place, where you check that levels?
Hello Avas,
Sorry for the late reply. Actually I am updating the radiation levels but on new pages. Here are the links for September and October:
http://chottomatte.net/2011/09/09/tokyo-radiation-levels-daily-updates-september
http://chottomatte.net/2011/10/03/tokyo-radiation-levels-daily-updates-october
Soon I will start a new webpage for November and I will post link.
Anyway for the last two month there were no any big changes apart for may be weak tendency toward even further decrease in the radiation level (but to be sure I must make a statistical analysis)
Hi Radar,
I am receiving the data from WAKO, RIKEN Campus. The detector is 1 meter above ground.