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  • The DOST-PNRI continues to closely monitor the situation at the Fukushima Daiichi Nuclear Power Plant. The condition in the plant remains very serious but is slowly getting better.
  • As of 4 May 2011, the radiation levels in 45 out of 47 prefectures are within the typical Japanese background levels of 50-100 nanosieverts per hour (nSv/h). Ibaraki prefecture showed a maximum dose rate of 104 nSv/h while Fukushima prefecture showed a maximum dose rate of 1,700 nSv/h.
  • As of 29 April 2011, the PNRI had analyzed 29 food samples imported from Japan. These had activities lower than 3 Bq/kg of Cesium-137 and Cesium-134 and were almost at the limit of detection. The WHO Codex Alimentarius Commission recommended limit for international trade is 1000 Bq/kg for total radioactivity in food.
  • The Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) air monitoring station in the Philippines being serviced by the DOST-PNRI detected the following radioactivity concentrations (in table and graph):

Day

Iodine-131
(µBq/m3)a

Cesium-134
(µBq/m3)

Cesium-137
(µBq/m3)

March 23

33

4.2

5.7

March 24

480

92

120

March 25

54

6.3

7.7

March 26

20

0.7

0.7

March 27

47

2.6

3.1

March 28

93

4.4

5.3

March 29

130

4.6

5.3

March 30

210

1.7

1.6

March 31

31

Not detected

0.7

April 1

57

4.3

5.7

April 2

61

9.9

12

April 3

160

86

100

April 4

79

53

79

April 5

51

18

20

April 6

21

8.7

11

April 7

12

4.2

4.6

April 8

73

23

28

April 9

95

22

25

April 10

140

21

26

April 11

80

16

20

April 12

53

8.1

11

April 13

45

13

17

April 14

30

17

21

April 15

26

16

21

April 16

23

22

28

April 17

21

17

21

April 18

15

9.4

14

April 19

12

5.7

7.2

April 20

7.5

9.8

12

April 21

5.3

6.4

7.8

April 22

6.2

4.8

5.9

April 23

6.9

3.1

6.9

April 24

5.5

2.2

3.8

April 25

4.6

2.8

2.5

April 26

1.4

0.64

Not detected

April 27

1.1

Not detected

Not detected

April 28

1.6

Not detected

Not detected

April 29

Not detected

Not detected

Not detected

April 30

Not detected

Not detected

Not detected

May 1 - present

Still being processed by CTBTO

  • The peak values on March 24 correspond to a dose of 131 nanosieverts in a year; sleeping next to someone for 8 hours a day for one year gives a dose of 20,000 nanosieverts because of the natural radioactivity present in the body.

Activity Concentration of Topsoil Samples taken from PNRI grounds and other sites:

DATE 
COLLECTED d

SITE

ACTIVITY CONCENTRATION, Bq/kg

Iodine-131

Cesium-134

Cesium-137

March 28

PNRI

Not detected

Not detected

0.064 b

March 28

PNRI

Not detected

Not detected

0.175 b

April 1

Gattaran, Cagayan

Not detected

Not detected

Not detected

April 4

Tuguegarao, Cagayan

Not detected

Not detected

0.867 b

April 5

La Mesa Dam

Not detected

Not detected

Not detected

April 5

La Mesa Dam

Not detected

Not detected

0.500 b

April 8

Site 1, Tanay, Rizal

Not detected

Not detected

Not detected

April 8

Site 2, Tanay, Rizal

Not detected

Not detected

Not detected

 Activity Concentration of Water Samples taken from various sites:

DATE 
COLLECTED d

SAMPLE TYPE/SITE

ACTIVITY CONCENTRATION, mBq/L c

Iodine-131

Cesium-134

Cesium-137

April 2

Seawater/Sta. Ana, Cagayan

Not detected

Not detected

1.66 b

April 5

Freshwater/La Mesa Dam

Not detected

Not detected

Not detected

April 13

Seawater/Baler, Aurora

Not detected

Not detected

2.70 b

 Activity Concentration of Fish Samples taken from Luzon:

DATE 
COLLECTED d

FISH TYPE/SITE

ACTIVITY CONCENTRATION, Bq/kg

Iodine-131

Cesium-134

Cesium-137

April 4

Dorado / Sta. Ana Fishport

Not detected

Not detected

0.164 b

April 4

Tulingan / Sta. Ana Fishport

Not detected

Not detected

Not detected

April 4

Bariles / Sta. Ana Fishport

Not detected

Not detected

Not detected

April 14

Malasugui / Baler, Aurora

Not detected

Not detected

0.57 b

April 14

Dalagang Bukid / Baler, Aurora

Not detected

Not detected

0.76 b

a microbecquerels per cubic meter; 1 microbecquerel = 1 x 10-6 becquerel

b The above Cesium-137 levels in the soil, water, and fish samples are within background levels. The Cesium-137 is residual activity from atmospheric nuclear weapons testing in the 1950’s and 1960’s, not from the Fukushima accident. 

c millibecquerels per liter; 1 millibecquerel = 1 x 10-3 becquerel; some copies of Information Bulletin No.22 may have erroneously stated this as Bq/kg instead of mBq/L

Dates corrected