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

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

Due to a power outage at our center due to statutory inspection of electrical equipment, we will temporarily suspend updating of monitoring post measurement values ​​from 8:00 to 19:00 on Saturday, October 18, 2025.

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
00:01-01:00, Mon., 15 Sep. 0.0290 0.0251 0.0271
23:01-24:00, Sun., 14 Sep. 0.0284 0.0240 0.0266
22:01-23:00, Sun., 14 Sep. 0.0287 0.0249 0.0268
21:01-22:00, Sun., 14 Sep. 0.0294 0.0252 0.0273
20:01-21:00, Sun., 14 Sep. 0.0293 0.0247 0.0274
19:01-20:00, Sun., 14 Sep. 0.0290 0.0242 0.0273
18:01-19:00, Sun., 14 Sep. 0.0292 0.0254 0.0271
17:01-18:00, Sun., 14 Sep. 0.0292 0.0246 0.0267
16:01-17:00, Sun., 14 Sep. 0.0292 0.0252 0.0268
15:01-16:00, Sun., 14 Sep. 0.0288 0.0252 0.0268
14:01-15:00, Sun., 14 Sep. 0.0293 0.0252 0.0270
13:01-14:00, Sun., 14 Sep. 0.0290 0.0251 0.0271
12:01-13:00, Sun., 14 Sep. 0.0290 0.0241 0.0269
11:01-12:00, Sun., 14 Sep. 0.0295 0.0247 0.0272
10:01-11:00, Sun., 14 Sep. 0.0292 0.0244 0.0275
09:01-10:00, Sun., 14 Sep. 0.0295 0.0249 0.0274
08:01-09:00, Sun., 14 Sep. 0.0303 0.0266 0.0280
07:01-08:00, Sun., 14 Sep. 0.0317 0.0271 0.0292
06:01-07:00, Sun., 14 Sep. 0.0327 0.0275 0.0303
05:01-06:00, Sun., 14 Sep. 0.0302 0.0248 0.0272
04:01-05:00, Sun., 14 Sep. 0.0281 0.0243 0.0267
03:01-04:00, Sun., 14 Sep. 0.0289 0.0248 0.0265
02:01-03:00, Sun., 14 Sep. 0.0285 0.0239 0.0267
01:01-02:00, Sun., 14 Sep. 0.0287 0.0242 0.0266
00:01-01:00, Sun., 14 Sep. 0.0287 0.0238 0.0260
23:01-24:00, Sat., 13 Sep. 0.0280 0.0235 0.0258
22:01-23:00, Sat., 13 Sep. 0.0276 0.0244 0.0260
21:01-22:00, Sat., 13 Sep. 0.0290 0.0241 0.0261
20:01-21:00, Sat., 13 Sep. 0.0280 0.0247 0.0263
19:01-20:00, Sat., 13 Sep. 0.0287 0.0244 0.0261
18:01-19:00, Sat., 13 Sep. 0.0282 0.0243 0.0264
17:01-18:00, Sat., 13 Sep. 0.0286 0.0245 0.0266
16:01-17:00, Sat., 13 Sep. 0.0283 0.0241 0.0262
15:01-16:00, Sat., 13 Sep. 0.0277 0.0245 0.0261
14:01-15:00, Sat., 13 Sep. 0.0287 0.0246 0.0261
13:01-14:00, Sat., 13 Sep. 0.0279 0.0238 0.0259
12:01-13:00, Sat., 13 Sep. 0.0292 0.0242 0.0260
11:01-12:00, Sat., 13 Sep. 0.0280 0.0245 0.0264
10:01-11:00, Sat., 13 Sep. 0.0281 0.0235 0.0262
09:01-10:00, Sat., 13 Sep. 0.0296 0.0245 0.0264
08:01-09:00, Sat., 13 Sep. 0.0298 0.0238 0.0273
07:01-08:00, Sat., 13 Sep. 0.0295 0.0252 0.0275
06:01-07:00, Sat., 13 Sep. 0.0292 0.0251 0.0268
05:01-06:00, Sat., 13 Sep. 0.0286 0.0249 0.0266
04:01-05:00, Sat., 13 Sep. 0.0318 0.0262 0.0287
03:01-04:00, Sat., 13 Sep. 0.0364 0.0294 0.0332
02:01-03:00, Sat., 13 Sep. 0.0364 0.0311 0.0337
01:01-02:00, Sat., 13 Sep. 0.0353 0.0307 0.0328
00:01-01:00, Sat., 13 Sep. 0.0347 0.0283 0.0315
23:01-24:00, Fri., 12 Sep. 0.0311 0.0262 0.0288
22:01-23:00, Fri., 12 Sep. 0.0339 0.0276 0.0310
21:01-22:00, Fri., 12 Sep. 0.0339 0.0287 0.0316
20:01-21:00, Fri., 12 Sep. 0.0318 0.0263 0.0287
19:01-20:00, Fri., 12 Sep. 0.0300 0.0250 0.0273
18:01-19:00, Fri., 12 Sep. 0.0290 0.0244 0.0263
17:01-18:00, Fri., 12 Sep. 0.0278 0.0248 0.0263
16:01-17:00, Fri., 12 Sep. 0.0293 0.0245 0.0267
15:01-16:00, Fri., 12 Sep. 0.0316 0.0258 0.0283
14:01-15:00, Fri., 12 Sep. 0.0322 0.0259 0.0285
13:01-14:00, Fri., 12 Sep. 0.0287 0.0250 0.0270
12:01-13:00, Fri., 12 Sep. 0.0304 0.0245 0.0274
11:01-12:00, Fri., 12 Sep. 0.0287 0.0238 0.0267
10:01-11:00, Fri., 12 Sep. 0.0287 0.0249 0.0268
09:01-10:00, Fri., 12 Sep. 0.0287 0.0244 0.0264
08:01-09:00, Fri., 12 Sep. 0.0287 0.0251 0.0268
07:01-08:00, Fri., 12 Sep. 0.0294 0.0246 0.0265
06:01-07:00, Fri., 12 Sep. 0.0285 0.0241 0.0265
05:01-06:00, Fri., 12 Sep. 0.0290 0.0248 0.0263
04:01-05:00, Fri., 12 Sep. 0.0280 0.0247 0.0264
03:01-04:00, Fri., 12 Sep. 0.0285 0.0235 0.0265
02:01-03:00, Fri., 12 Sep. 0.0315 0.0258 0.0288
01:01-02:00, Fri., 12 Sep. 0.0404 0.0297 0.0350
00:01-01:00, Fri., 12 Sep. 0.0437 0.0343 0.0399
23:01-24:00, Thu., 11 Sep. 0.0370 0.0270 0.0313
22:01-23:00, Thu., 11 Sep. 0.0301 0.0259 0.0281
21:01-22:00, Thu., 11 Sep. 0.0304 0.0257 0.0282
20:01-21:00, Thu., 11 Sep. 0.0337 0.0282 0.0304
19:01-20:00, Thu., 11 Sep. 0.0322 0.0249 0.0287
18:01-19:00, Thu., 11 Sep. 0.0297 0.0256 0.0272
17:01-18:00, Thu., 11 Sep. 0.0297 0.0246 0.0278
16:01-17:00, Thu., 11 Sep. 0.0346 0.0276 0.0307
15:01-16:00, Thu., 11 Sep. 0.0393 0.0319 0.0361
14:01-15:00, Thu., 11 Sep. 0.0354 0.0252 0.0295
13:01-14:00, Thu., 11 Sep. 0.0291 0.0255 0.0274
12:01-13:00, Thu., 11 Sep. 0.0294 0.0253 0.0275
11:01-12:00, Thu., 11 Sep. 0.0297 0.0253 0.0277
10:01-11:00, Thu., 11 Sep. 0.0298 0.0257 0.0279
09:01-10:00, Thu., 11 Sep. 0.0305 0.0264 0.0281
08:01-09:00, Thu., 11 Sep. 0.0304 0.0256 0.0278
07:01-08:00, Thu., 11 Sep. 0.0304 0.0257 0.0278
06:01-07:00, Thu., 11 Sep. 0.0309 0.0254 0.0279
05:01-06:00, Thu., 11 Sep. 0.0308 0.0270 0.0286
04:01-05:00, Thu., 11 Sep. 0.0296 0.0253 0.0274
03:01-04:00, Thu., 11 Sep. 0.0294 0.0249 0.0270
02:01-03:00, Thu., 11 Sep. 0.0288 0.0246 0.0266
01:01-02:00, Thu., 11 Sep. 0.0288 0.0248 0.0268
00:01-01:00, Thu., 11 Sep. 0.0284 0.0235 0.0266
23:01-24:00, Wed., 10 Sep. 0.0282 0.0243 0.0266
22:01-23:00, Wed., 10 Sep. 0.0286 0.0243 0.0266
21:01-22:00, Wed., 10 Sep. 0.0286 0.0245 0.0266
20:01-21:00, Wed., 10 Sep. 0.0289 0.0252 0.0269
19:01-20:00, Wed., 10 Sep. 0.0302 0.0244 0.0268
18:01-19:00, Wed., 10 Sep. 0.0286 0.0248 0.0270
17:01-18:00, Wed., 10 Sep. 0.0291 0.0248 0.0269
16:01-17:00, Wed., 10 Sep. 0.0286 0.0245 0.0267
15:01-16:00, Wed., 10 Sep. 0.0290 0.0253 0.0272
14:01-15:00, Wed., 10 Sep. 0.0293 0.0249 0.0272
13:01-14:00, Wed., 10 Sep. 0.0301 0.0252 0.0279
12:01-13:00, Wed., 10 Sep. 0.0303 0.0261 0.0282
11:01-12:00, Wed., 10 Sep. 0.0317 0.0254 0.0279
10:01-11:00, Wed., 10 Sep. 0.0305 0.0256 0.0275
09:01-10:00, Wed., 10 Sep. 0.0309 0.0258 0.0280
08:01-09:00, Wed., 10 Sep. 0.0297 0.0260 0.0278
07:01-08:00, Wed., 10 Sep. 0.0302 0.0249 0.0280
06:01-07:00, Wed., 10 Sep. 0.0297 0.0259 0.0276
05:01-06:00, Wed., 10 Sep. 0.0293 0.0252 0.0274
04:01-05:00, Wed., 10 Sep. 0.0301 0.0258 0.0279
03:01-04:00, Wed., 10 Sep. 0.0301 0.0258 0.0278
02:01-03:00, Wed., 10 Sep. 0.0293 0.0259 0.0276
01:01-02:00, Wed., 10 Sep. 0.0298 0.0253 0.0279
00:01-01:00, Wed., 10 Sep. 0.0300 0.0259 0.0279
23:01-24:00, Tue., 09 Sep. 0.0304 0.0261 0.0279
22:01-23:00, Tue., 09 Sep. 0.0307 0.0254 0.0280
21:01-22:00, Tue., 09 Sep. 0.0300 0.0258 0.0277
20:01-21:00, Tue., 09 Sep. 0.0300 0.0255 0.0278
19:01-20:00, Tue., 09 Sep. 0.0298 0.0259 0.0277
18:01-19:00, Tue., 09 Sep. 0.0303 0.0259 0.0278
17:01-18:00, Tue., 09 Sep. 0.0296 0.0257 0.0276
16:01-17:00, Tue., 09 Sep. 0.0296 0.0260 0.0277
15:01-16:00, Tue., 09 Sep. 0.0306 0.0249 0.0276
14:01-15:00, Tue., 09 Sep. 0.0290 0.0256 0.0275
13:01-14:00, Tue., 09 Sep. 0.0298 0.0261 0.0278
12:01-13:00, Tue., 09 Sep. 0.0298 0.0255 0.0277
11:01-12:00, Tue., 09 Sep. 0.0296 0.0259 0.0276
10:01-11:00, Tue., 09 Sep. 0.0297 0.0257 0.0276
09:01-10:00, Tue., 09 Sep. 0.0299 0.0256 0.0276
08:01-09:00, Tue., 09 Sep. 0.0301 0.0256 0.0278
07:01-08:00, Tue., 09 Sep. 0.0304 0.0263 0.0279
06:01-07:00, Tue., 09 Sep. 0.0294 0.0249 0.0278
05:01-06:00, Tue., 09 Sep. 0.0301 0.0257 0.0278
04:01-05:00, Tue., 09 Sep. 0.0300 0.0257 0.0275
03:01-04:00, Tue., 09 Sep. 0.0290 0.0255 0.0273
02:01-03:00, Tue., 09 Sep. 0.0297 0.0251 0.0272
01:01-02:00, Tue., 09 Sep. 0.0303 0.0256 0.0275
00:01-01:00, Tue., 09 Sep. 0.0298 0.0252 0.0273
23:01-24:00, Mon., 08 Sep. 0.0292 0.0256 0.0278
22:01-23:00, Mon., 08 Sep. 0.0293 0.0249 0.0274
21:01-22:00, Mon., 08 Sep. 0.0298 0.0253 0.0276
20:01-21:00, Mon., 08 Sep. 0.0291 0.0246 0.0271
19:01-20:00, Mon., 08 Sep. 0.0293 0.0255 0.0272
18:01-19:00, Mon., 08 Sep. 0.0298 0.0252 0.0274
17:01-18:00, Mon., 08 Sep. 0.0290 0.0259 0.0275
16:01-17:00, Mon., 08 Sep. 0.0302 0.0258 0.0274
15:01-16:00, Mon., 08 Sep. 0.0299 0.0261 0.0275
14:01-15:00, Mon., 08 Sep. 0.0299 0.0254 0.0274
13:01-14:00, Mon., 08 Sep. 0.0295 0.0256 0.0274
12:01-13:00, Mon., 08 Sep. 0.0298 0.0262 0.0279
11:01-12:00, Mon., 08 Sep. 0.0301 0.0260 0.0281
10:01-11:00, Mon., 08 Sep. 0.0301 0.0259 0.0280
09:01-10:00, Mon., 08 Sep. 0.0304 0.0266 0.0281
08:01-09:00, Mon., 08 Sep. 0.0309 0.0259 0.0285
07:01-08:00, Mon., 08 Sep. 0.0312 0.0270 0.0294
06:01-07:00, Mon., 08 Sep. 0.0329 0.0281 0.0304
05:01-06:00, Mon., 08 Sep. 0.0321 0.0283 0.0300
04:01-05:00, Mon., 08 Sep. 0.0319 0.0275 0.0297
03:01-04:00, Mon., 08 Sep. 0.0313 0.0256 0.0290
02:01-03:00, Mon., 08 Sep. 0.0298 0.0251 0.0276
01:01-02:00, Mon., 08 Sep. 0.0295 0.0253 0.0271
00:01-01:00, Mon., 08 Sep. 0.0299 0.0250 0.0272
23:01-24:00, Sun., 07 Sep. 0.0291 0.0240 0.0268
22:01-23:00, Sun., 07 Sep. 0.0289 0.0249 0.0268
21:01-22:00, Sun., 07 Sep. 0.0288 0.0251 0.0267
20:01-21:00, Sun., 07 Sep. 0.0294 0.0246 0.0267
19:01-20:00, Sun., 07 Sep. 0.0287 0.0246 0.0267
18:01-19:00, Sun., 07 Sep. 0.0286 0.0246 0.0269
17:01-18:00, Sun., 07 Sep. 0.0291 0.0252 0.0270
16:01-17:00, Sun., 07 Sep. 0.0293 0.0248 0.0271
15:01-16:00, Sun., 07 Sep. 0.0289 0.0249 0.0271
14:01-15:00, Sun., 07 Sep. 0.0294 0.0246 0.0272
13:01-14:00, Sun., 07 Sep. 0.0293 0.0247 0.0267
12:01-13:00, Sun., 07 Sep. 0.0294 0.0242 0.0268
11:01-12:00, Sun., 07 Sep. 0.0296 0.0249 0.0268
10:01-11:00, Sun., 07 Sep. 0.0290 0.0248 0.0269
09:01-10:00, Sun., 07 Sep. 0.0289 0.0248 0.0271
08:01-09:00, Sun., 07 Sep. 0.0302 0.0259 0.0278
07:01-08:00, Sun., 07 Sep. 0.0306 0.0262 0.0282
06:01-07:00, Sun., 07 Sep. 0.0304 0.0263 0.0282
05:01-06:00, Sun., 07 Sep. 0.0295 0.0243 0.0272
04:01-05:00, Sun., 07 Sep. 0.0296 0.0253 0.0271
03:01-04:00, Sun., 07 Sep. 0.0286 0.0249 0.0267
02:01-03:00, Sun., 07 Sep. 0.0283 0.0244 0.0268
01:01-02:00, Sun., 07 Sep. 0.0287 0.0242 0.0266
00:01-01:00, Sun., 07 Sep. 0.0286 0.0249 0.0266
23:01-24:00, Sat., 06 Sep. 0.0287 0.0251 0.0269
22:01-23:00, Sat., 06 Sep. 0.0297 0.0245 0.0269
21:01-22:00, Sat., 06 Sep. 0.0294 0.0244 0.0267
20:01-21:00, Sat., 06 Sep. 0.0287 0.0251 0.0268
19:01-20:00, Sat., 06 Sep. 0.0287 0.0240 0.0266
18:01-19:00, Sat., 06 Sep. 0.0286 0.0251 0.0266
17:01-18:00, Sat., 06 Sep. 0.0298 0.0249 0.0269
16:01-17:00, Sat., 06 Sep. 0.0286 0.0250 0.0269
15:01-16:00, Sat., 06 Sep. 0.0290 0.0254 0.0270
14:01-15:00, Sat., 06 Sep. 0.0286 0.0251 0.0268
13:01-14:00, Sat., 06 Sep. 0.0295 0.0249 0.0271
12:01-13:00, Sat., 06 Sep. 0.0295 0.0252 0.0270
11:01-12:00, Sat., 06 Sep. 0.0289 0.0252 0.0270
10:01-11:00, Sat., 06 Sep. 0.0293 0.0250 0.0269
09:01-10:00, Sat., 06 Sep. 0.0296 0.0251 0.0274
08:01-09:00, Sat., 06 Sep. 0.0294 0.0254 0.0275
07:01-08:00, Sat., 06 Sep. 0.0298 0.0262 0.0281
06:01-07:00, Sat., 06 Sep. 0.0299 0.0263 0.0278
05:01-06:00, Sat., 06 Sep. 0.0303 0.0249 0.0274
04:01-05:00, Sat., 06 Sep. 0.0298 0.0256 0.0273
03:01-04:00, Sat., 06 Sep. 0.0298 0.0252 0.0272
02:01-03:00, Sat., 06 Sep. 0.0287 0.0256 0.0272
01:01-02:00, Sat., 06 Sep. 0.0306 0.0256 0.0276
00:01-01:00, Sat., 06 Sep. 0.0298 0.0250 0.0273
23:01-24:00, Fri., 05 Sep. 0.0291 0.0249 0.0273
22:01-23:00, Fri., 05 Sep. 0.0294 0.0243 0.0267
21:01-22:00, Fri., 05 Sep. 0.0285 0.0242 0.0266
20:01-21:00, Fri., 05 Sep. 0.0286 0.0251 0.0265
19:01-20:00, Fri., 05 Sep. 0.0288 0.0238 0.0267
18:01-19:00, Fri., 05 Sep. 0.0284 0.0245 0.0266
17:01-18:00, Fri., 05 Sep. 0.0295 0.0252 0.0273
16:01-17:00, Fri., 05 Sep. 0.0329 0.0273 0.0298
15:01-16:00, Fri., 05 Sep. 0.0377 0.0318 0.0349
14:01-15:00, Fri., 05 Sep. 0.0395 0.0343 0.0366
13:01-14:00, Fri., 05 Sep. 0.0378 0.0302 0.0341
12:01-13:00, Fri., 05 Sep. 0.0343 0.0266 0.0289
11:01-12:00, Fri., 05 Sep. 0.0302 0.0249 0.0275
10:01-11:00, Fri., 05 Sep. 0.0298 0.0249 0.0274
09:01-10:00, Fri., 05 Sep. 0.0291 0.0246 0.0276
08:01-09:00, Fri., 05 Sep. 0.0297 0.0260 0.0277
07:01-08:00, Fri., 05 Sep. 0.0296 0.0250 0.0273
06:01-07:00, Fri., 05 Sep. 0.0304 0.0256 0.0275
05:01-06:00, Fri., 05 Sep. 0.0299 0.0256 0.0277
04:01-05:00, Fri., 05 Sep. 0.0289 0.0251 0.0269
03:01-04:00, Fri., 05 Sep. 0.0286 0.0245 0.0269
02:01-03:00, Fri., 05 Sep. 0.0304 0.0252 0.0273
01:01-02:00, Fri., 05 Sep. 0.0290 0.0245 0.0271