Radiation doses in the air / Measurement results by the hour (Koto)

We continuously measure radiation doses in the air (air absorbed doses per hour) at monitoring posts. Measurement results can be obtained by the minute, and we gather measurement data and then display them by the hour or by the day.

The maximum value indicates the largest value measured in each time slot (during the hour or during the day), the minimum value the smallest value measured in each time slot, and the average value is the average value for each time slot.

News about this monitoring post

We will update the monitoring post from Wednesday, March 8 to Thursday, March 9, 2023. Since it is not possible to measure the radiation dose in the atmosphere during the update work, the provision of measurement results will be temporarily suspended at the following monitoring posts.

Adachi Bureau (Toneri Park) Wednesday, March 8, from around 8 a.m. to 6 p.m.
Chofu Bureau (Chofu Airfield) Thursday, March 9, from 8 a.m. to 6 p.m.


On Friday, March 10, 2023, from around 9 a.m. to around noon, maintenance and inspection of the Kodaira Bureau (Medicinal Botanical Garden) will be conducted.
Since the amount of radiation in the atmosphere cannot be measured during maintenance and inspection, the provision of measurement results is temporarily suspended.
We have been conducting an extraordinary inspection since February 13, 2023, and we were able to confirm that the measuring instrument is operating normally. Since this was an extraordinary inspection of peripheral equipment, it has been confirmed that there are no abnormalities in the measuring instrument, so we will disclose the measured values during the extraordinary inspection period. In addition, in order to check the operating status of the measuring instrument during the extraordinary inspection, a high dose of the substance was intentionally brought close to the sensor, so the measured value is temporarily high.

Shown in µGy/h (microgray per hour)

Gray indicates an amount of energy (absorbed dose) when radiation hits a material object, and 1 gray (Gy) of radiation doses in the air can be converted to 1 sievert (Sv).

Measurement time Dose rate
μGy/h (microgray per hour)
Maximum value Minimum value Average value
17:01-18:00, Fri., 02 Jun. 0.0422 0.0360 0.0389
16:01-17:00, Fri., 02 Jun. 0.0399 0.0347 0.0369
15:01-16:00, Fri., 02 Jun. 0.0395 0.0352 0.0373
14:01-15:00, Fri., 02 Jun. 0.0386 0.0352 0.0371
13:01-14:00, Fri., 02 Jun. 0.0400 0.0354 0.0375
12:01-13:00, Fri., 02 Jun. 0.0405 0.0353 0.0375
11:01-12:00, Fri., 02 Jun. 0.0412 0.0353 0.0376
10:01-11:00, Fri., 02 Jun. 0.0403 0.0354 0.0382
09:01-10:00, Fri., 02 Jun. 0.0398 0.0361 0.0379
08:01-09:00, Fri., 02 Jun. 0.0411 0.0363 0.0387
07:01-08:00, Fri., 02 Jun. 0.0417 0.0381 0.0401
06:01-07:00, Fri., 02 Jun. 0.0426 0.0378 0.0404
05:01-06:00, Fri., 02 Jun. 0.0435 0.0389 0.0411
04:01-05:00, Fri., 02 Jun. 0.0455 0.0404 0.0428
03:01-04:00, Fri., 02 Jun. 0.0462 0.0396 0.0421
02:01-03:00, Fri., 02 Jun. 0.0424 0.0376 0.0398
01:01-02:00, Fri., 02 Jun. 0.0438 0.0369 0.0408
00:01-01:00, Fri., 02 Jun. 0.0431 0.0368 0.0397
23:01-24:00, Thu., 01 Jun. 0.0395 0.0350 0.0371
22:01-23:00, Thu., 01 Jun. 0.0389 0.0336 0.0367
21:01-22:00, Thu., 01 Jun. 0.0388 0.0346 0.0366
20:01-21:00, Thu., 01 Jun. 0.0391 0.0346 0.0365
19:01-20:00, Thu., 01 Jun. 0.0388 0.0346 0.0368
18:01-19:00, Thu., 01 Jun. 0.0387 0.0343 0.0368
17:01-18:00, Thu., 01 Jun. 0.0397 0.0350 0.0368
16:01-17:00, Thu., 01 Jun. 0.0379 0.0338 0.0365
15:01-16:00, Thu., 01 Jun. 0.0388 0.0348 0.0366
14:01-15:00, Thu., 01 Jun. 0.0382 0.0339 0.0363
13:01-14:00, Thu., 01 Jun. 0.0383 0.0338 0.0363
12:01-13:00, Thu., 01 Jun. 0.0388 0.0345 0.0366
11:01-12:00, Thu., 01 Jun. 0.0383 0.0347 0.0363
10:01-11:00, Thu., 01 Jun. 0.0383 0.0345 0.0365
09:01-10:00, Thu., 01 Jun. 0.0389 0.0343 0.0364
08:01-09:00, Thu., 01 Jun. 0.0391 0.0347 0.0368
07:01-08:00, Thu., 01 Jun. 0.0384 0.0347 0.0363
06:01-07:00, Thu., 01 Jun. 0.0391 0.0347 0.0367
05:01-06:00, Thu., 01 Jun. 0.0382 0.0336 0.0365
04:01-05:00, Thu., 01 Jun. 0.0386 0.0343 0.0365
03:01-04:00, Thu., 01 Jun. 0.0378 0.0346 0.0364
02:01-03:00, Thu., 01 Jun. 0.0384 0.0337 0.0366
01:01-02:00, Thu., 01 Jun. 0.0382 0.0344 0.0365
00:01-01:00, Thu., 01 Jun. 0.0385 0.0347 0.0365
23:01-24:00, Wed., 31 May. 0.0381 0.0342 0.0364
22:01-23:00, Wed., 31 May. 0.0383 0.0341 0.0366
21:01-22:00, Wed., 31 May. 0.0388 0.0346 0.0365
20:01-21:00, Wed., 31 May. 0.0380 0.0347 0.0364
19:01-20:00, Wed., 31 May. 0.0385 0.0339 0.0364
18:01-19:00, Wed., 31 May. 0.0387 0.0340 0.0365
17:01-18:00, Wed., 31 May. 0.0381 0.0347 0.0363
16:01-17:00, Wed., 31 May. 0.0384 0.0342 0.0363
15:01-16:00, Wed., 31 May. 0.0383 0.0343 0.0363
14:01-15:00, Wed., 31 May. 0.0386 0.0345 0.0364
13:01-14:00, Wed., 31 May. 0.0391 0.0338 0.0363
12:01-13:00, Wed., 31 May. 0.0396 0.0340 0.0363
11:01-12:00, Wed., 31 May. 0.0386 0.0340 0.0361
10:01-11:00, Wed., 31 May. 0.0383 0.0343 0.0363
09:01-10:00, Wed., 31 May. 0.0389 0.0345 0.0363
08:01-09:00, Wed., 31 May. 0.0386 0.0345 0.0367
07:01-08:00, Wed., 31 May. 0.0392 0.0341 0.0369
06:01-07:00, Wed., 31 May. 0.0422 0.0364 0.0388
05:01-06:00, Wed., 31 May. 0.0460 0.0391 0.0423
04:01-05:00, Wed., 31 May. 0.0469 0.0374 0.0412
03:01-04:00, Wed., 31 May. 0.0407 0.0350 0.0383
02:01-03:00, Wed., 31 May. 0.0396 0.0348 0.0372
01:01-02:00, Wed., 31 May. 0.0388 0.0340 0.0365
00:01-01:00, Wed., 31 May. 0.0386 0.0350 0.0366
23:01-24:00, Tue., 30 May. 0.0387 0.0346 0.0367
22:01-23:00, Tue., 30 May. 0.0393 0.0343 0.0365
21:01-22:00, Tue., 30 May. 0.0390 0.0347 0.0363
20:01-21:00, Tue., 30 May. 0.0380 0.0343 0.0364
19:01-20:00, Tue., 30 May. 0.0392 0.0350 0.0365
18:01-19:00, Tue., 30 May. 0.0388 0.0344 0.0365
17:01-18:00, Tue., 30 May. 0.0388 0.0357 0.0369
16:01-17:00, Tue., 30 May. 0.0387 0.0346 0.0367
15:01-16:00, Tue., 30 May. 0.0391 0.0347 0.0368
14:01-15:00, Tue., 30 May. 0.0388 0.0341 0.0366
13:01-14:00, Tue., 30 May. 0.0395 0.0343 0.0368
12:01-13:00, Tue., 30 May. 0.0384 0.0343 0.0364
11:01-12:00, Tue., 30 May. 0.0388 0.0352 0.0370
10:01-11:00, Tue., 30 May. 0.0388 0.0344 0.0367
09:01-10:00, Tue., 30 May. 0.0391 0.0350 0.0372
08:01-09:00, Tue., 30 May. 0.0401 0.0360 0.0382
07:01-08:00, Tue., 30 May. 0.0396 0.0353 0.0375
06:01-07:00, Tue., 30 May. 0.0401 0.0357 0.0379
05:01-06:00, Tue., 30 May. 0.0407 0.0360 0.0380
04:01-05:00, Tue., 30 May. 0.0397 0.0352 0.0371
03:01-04:00, Tue., 30 May. 0.0386 0.0347 0.0365
02:01-03:00, Tue., 30 May. 0.0398 0.0340 0.0366
01:01-02:00, Tue., 30 May. 0.0390 0.0356 0.0373
00:01-01:00, Tue., 30 May. 0.0420 0.0371 0.0392
23:01-24:00, Mon., 29 May. 0.0443 0.0381 0.0414
22:01-23:00, Mon., 29 May. 0.0474 0.0419 0.0446
21:01-22:00, Mon., 29 May. 0.0484 0.0439 0.0462
20:01-21:00, Mon., 29 May. 0.0474 0.0409 0.0438
19:01-20:00, Mon., 29 May. 0.0435 0.0374 0.0410
18:01-19:00, Mon., 29 May. 0.0429 0.0379 0.0404
17:01-18:00, Mon., 29 May. 0.0436 0.0374 0.0405
16:01-17:00, Mon., 29 May. 0.0427 0.0370 0.0404
15:01-16:00, Mon., 29 May. 0.0433 0.0388 0.0411
14:01-15:00, Mon., 29 May. 0.0430 0.0379 0.0404
13:01-14:00, Mon., 29 May. 0.0394 0.0350 0.0373
12:01-13:00, Mon., 29 May. 0.0405 0.0353 0.0371
11:01-12:00, Mon., 29 May. 0.0411 0.0359 0.0380
10:01-11:00, Mon., 29 May. 0.0429 0.0380 0.0404
09:01-10:00, Mon., 29 May. 0.0453 0.0384 0.0415
08:01-09:00, Mon., 29 May. 0.0450 0.0404 0.0425
07:01-08:00, Mon., 29 May. 0.0440 0.0392 0.0413
06:01-07:00, Mon., 29 May. 0.0457 0.0392 0.0430
05:01-06:00, Mon., 29 May. 0.0459 0.0398 0.0428
04:01-05:00, Mon., 29 May. 0.0443 0.0395 0.0419
03:01-04:00, Mon., 29 May. 0.0447 0.0396 0.0419
02:01-03:00, Mon., 29 May. 0.0414 0.0356 0.0387
01:01-02:00, Mon., 29 May. 0.0397 0.0357 0.0378
00:01-01:00, Mon., 29 May. 0.0397 0.0350 0.0375
23:01-24:00, Sun., 28 May. 0.0399 0.0364 0.0382
22:01-23:00, Sun., 28 May. 0.0421 0.0373 0.0400
21:01-22:00, Sun., 28 May. 0.0410 0.0344 0.0381
20:01-21:00, Sun., 28 May. 0.0399 0.0344 0.0372
19:01-20:00, Sun., 28 May. 0.0402 0.0351 0.0374
18:01-19:00, Sun., 28 May. 0.0391 0.0346 0.0370
17:01-18:00, Sun., 28 May. 0.0395 0.0345 0.0366
16:01-17:00, Sun., 28 May. 0.0395 0.0347 0.0369
15:01-16:00, Sun., 28 May. 0.0387 0.0340 0.0367
14:01-15:00, Sun., 28 May. 0.0385 0.0353 0.0370
13:01-14:00, Sun., 28 May. 0.0393 0.0341 0.0367
12:01-13:00, Sun., 28 May. 0.0385 0.0352 0.0366
11:01-12:00, Sun., 28 May. 0.0385 0.0353 0.0367
10:01-11:00, Sun., 28 May. 0.0388 0.0350 0.0370
09:01-10:00, Sun., 28 May. 0.0387 0.0346 0.0367
08:01-09:00, Sun., 28 May. 0.0401 0.0353 0.0367
07:01-08:00, Sun., 28 May. 0.0384 0.0346 0.0366
06:01-07:00, Sun., 28 May. 0.0391 0.0345 0.0367
05:01-06:00, Sun., 28 May. 0.0385 0.0348 0.0370
04:01-05:00, Sun., 28 May. 0.0391 0.0345 0.0367
03:01-04:00, Sun., 28 May. 0.0386 0.0343 0.0368
02:01-03:00, Sun., 28 May. 0.0388 0.0345 0.0369
01:01-02:00, Sun., 28 May. 0.0398 0.0349 0.0369
00:01-01:00, Sun., 28 May. 0.0388 0.0350 0.0369
23:01-24:00, Sat., 27 May. 0.0389 0.0344 0.0367
22:01-23:00, Sat., 27 May. 0.0383 0.0343 0.0366
21:01-22:00, Sat., 27 May. 0.0381 0.0350 0.0366
20:01-21:00, Sat., 27 May. 0.0387 0.0337 0.0366
19:01-20:00, Sat., 27 May. 0.0387 0.0345 0.0366
18:01-19:00, Sat., 27 May. 0.0382 0.0346 0.0365
17:01-18:00, Sat., 27 May. 0.0397 0.0348 0.0370
16:01-17:00, Sat., 27 May. 0.0390 0.0346 0.0370
15:01-16:00, Sat., 27 May. 0.0391 0.0341 0.0370
14:01-15:00, Sat., 27 May. 0.0385 0.0349 0.0372
13:01-14:00, Sat., 27 May. 0.0390 0.0347 0.0367
12:01-13:00, Sat., 27 May. 0.0390 0.0336 0.0370
11:01-12:00, Sat., 27 May. 0.0391 0.0352 0.0368
10:01-11:00, Sat., 27 May. 0.0388 0.0343 0.0369
09:01-10:00, Sat., 27 May. 0.0391 0.0347 0.0369
08:01-09:00, Sat., 27 May. 0.0389 0.0345 0.0367
07:01-08:00, Sat., 27 May. 0.0396 0.0351 0.0370
06:01-07:00, Sat., 27 May. 0.0392 0.0351 0.0369
05:01-06:00, Sat., 27 May. 0.0388 0.0331 0.0364
04:01-05:00, Sat., 27 May. 0.0388 0.0347 0.0367
03:01-04:00, Sat., 27 May. 0.0388 0.0343 0.0366
02:01-03:00, Sat., 27 May. 0.0401 0.0343 0.0367
01:01-02:00, Sat., 27 May. 0.0405 0.0341 0.0368
00:01-01:00, Sat., 27 May. 0.0386 0.0349 0.0367
23:01-24:00, Fri., 26 May. 0.0390 0.0331 0.0368
22:01-23:00, Fri., 26 May. 0.0389 0.0338 0.0367
21:01-22:00, Fri., 26 May. 0.0390 0.0345 0.0367
20:01-21:00, Fri., 26 May. 0.0384 0.0348 0.0367
19:01-20:00, Fri., 26 May. 0.0387 0.0340 0.0366
18:01-19:00, Fri., 26 May. 0.0392 0.0341 0.0366
17:01-18:00, Fri., 26 May. 0.0394 0.0347 0.0367
16:01-17:00, Fri., 26 May. 0.0388 0.0336 0.0365
15:01-16:00, Fri., 26 May. 0.0391 0.0347 0.0367
14:01-15:00, Fri., 26 May. 0.0384 0.0345 0.0366
13:01-14:00, Fri., 26 May. 0.0391 0.0337 0.0365
12:01-13:00, Fri., 26 May. 0.0386 0.0347 0.0363
11:01-12:00, Fri., 26 May. 0.0385 0.0347 0.0365
10:01-11:00, Fri., 26 May. 0.0389 0.0343 0.0364
09:01-10:00, Fri., 26 May. 0.0383 0.0335 0.0364
08:01-09:00, Fri., 26 May. 0.0394 0.0338 0.0366
07:01-08:00, Fri., 26 May. 0.0384 0.0342 0.0366
06:01-07:00, Fri., 26 May. 0.0392 0.0347 0.0367
05:01-06:00, Fri., 26 May. 0.0386 0.0347 0.0366
04:01-05:00, Fri., 26 May. 0.0384 0.0350 0.0368
03:01-04:00, Fri., 26 May. 0.0391 0.0344 0.0365
02:01-03:00, Fri., 26 May. 0.0386 0.0336 0.0364
01:01-02:00, Fri., 26 May. 0.0387 0.0335 0.0364
00:01-01:00, Fri., 26 May. 0.0391 0.0348 0.0367
23:01-24:00, Thu., 25 May. 0.0391 0.0343 0.0367
22:01-23:00, Thu., 25 May. 0.0395 0.0343 0.0365
21:01-22:00, Thu., 25 May. 0.0395 0.0346 0.0366
20:01-21:00, Thu., 25 May. 0.0388 0.0343 0.0366
19:01-20:00, Thu., 25 May. 0.0392 0.0350 0.0365
18:01-19:00, Thu., 25 May. 0.0383 0.0347 0.0366
17:01-18:00, Thu., 25 May. 0.0391 0.0340 0.0365
16:01-17:00, Thu., 25 May. 0.0386 0.0339 0.0367
15:01-16:00, Thu., 25 May. 0.0398 0.0347 0.0365
14:01-15:00, Thu., 25 May. 0.0390 0.0343 0.0366
13:01-14:00, Thu., 25 May. 0.0388 0.0340 0.0366
12:01-13:00, Thu., 25 May. 0.0391 0.0343 0.0368
11:01-12:00, Thu., 25 May. 0.0393 0.0347 0.0367
10:01-11:00, Thu., 25 May. 0.0391 0.0340 0.0366
09:01-10:00, Thu., 25 May. 0.0389 0.0340 0.0364
08:01-09:00, Thu., 25 May. 0.0381 0.0345 0.0366
07:01-08:00, Thu., 25 May. 0.0390 0.0348 0.0371
06:01-07:00, Thu., 25 May. 0.0388 0.0348 0.0368
05:01-06:00, Thu., 25 May. 0.0396 0.0347 0.0367
04:01-05:00, Thu., 25 May. 0.0391 0.0339 0.0366
03:01-04:00, Thu., 25 May. 0.0388 0.0346 0.0366
02:01-03:00, Thu., 25 May. 0.0387 0.0343 0.0366
01:01-02:00, Thu., 25 May. 0.0397 0.0343 0.0365
00:01-01:00, Thu., 25 May. 0.0394 0.0338 0.0366
23:01-24:00, Wed., 24 May. 0.0388 0.0345 0.0366
22:01-23:00, Wed., 24 May. 0.0390 0.0344 0.0367
21:01-22:00, Wed., 24 May. 0.0384 0.0347 0.0367
20:01-21:00, Wed., 24 May. 0.0387 0.0339 0.0366
19:01-20:00, Wed., 24 May. 0.0390 0.0337 0.0367
18:01-19:00, Wed., 24 May. 0.0395 0.0346 0.0368
17:01-18:00, Wed., 24 May. 0.0391 0.0344 0.0368
16:01-17:00, Wed., 24 May. 0.0388 0.0351 0.0368
15:01-16:00, Wed., 24 May. 0.0390 0.0344 0.0370
14:01-15:00, Wed., 24 May. 0.0388 0.0333 0.0364
13:01-14:00, Wed., 24 May. 0.0386 0.0341 0.0363
12:01-13:00, Wed., 24 May. 0.0382 0.0342 0.0364
11:01-12:00, Wed., 24 May. 0.0391 0.0344 0.0364
10:01-11:00, Wed., 24 May. 0.0386 0.0343 0.0362
09:01-10:00, Wed., 24 May. 0.0385 0.0344 0.0364
08:01-09:00, Wed., 24 May. 0.0383 0.0344 0.0367
07:01-08:00, Wed., 24 May. 0.0384 0.0347 0.0366
06:01-07:00, Wed., 24 May. 0.0391 0.0343 0.0366
05:01-06:00, Wed., 24 May. 0.0390 0.0350 0.0367
04:01-05:00, Wed., 24 May. 0.0391 0.0346 0.0369
03:01-04:00, Wed., 24 May. 0.0393 0.0344 0.0367
02:01-03:00, Wed., 24 May. 0.0400 0.0337 0.0368
01:01-02:00, Wed., 24 May. 0.0388 0.0348 0.0369
00:01-01:00, Wed., 24 May. 0.0384 0.0343 0.0367
23:01-24:00, Tue., 23 May. 0.0393 0.0349 0.0371
22:01-23:00, Tue., 23 May. 0.0409 0.0359 0.0380
21:01-22:00, Tue., 23 May. 0.0403 0.0351 0.0378
20:01-21:00, Tue., 23 May. 0.0383 0.0345 0.0367
19:01-20:00, Tue., 23 May. 0.0398 0.0344 0.0369
18:01-19:00, Tue., 23 May. 0.0384 0.0345 0.0367