After the accident caused by Tohoku-Chihou-Taiheiyo-Oki Earthquake on 
March 11, 2011, we have required the workers to wear full face masks 
(including half face masks) in the whole area of Fukushima Daiichi Nuclear 
Power Station except in the Main Anti-earthquake Building or the lounges. 
However, as a result of the countermeasure to the convergence with full 
effort, the density of the radioactive materials in the air of the power 
station has been gradually declining. Therefore, we have permitted the 
workers to omit wearing the masks in the certain areas such as the places 
where they pass by vehicles to go to the Main Anti-Earthquake Building in 
order to mitigate the inconvenience for the workers since November 8, 2011. 
                                (Previously announced on November 1, 2011) 
 
At Fukushima Daiichi Nuclear Power Station, we have required the workers 
to wear charcoal filter masks which have the function of collecting iodine 
and particles, as iodine was the dominant radioactive material in the site 
right after the Tohoku - Pacific Ocean Earthquake on March 11, 2011. 
Except in the Main Anti-earthquake Building or the lounges, since the 
occurrence of Tohoku - Pacific Ocean Earthquake, the workers have been 
required to wear non-woven coveralls (such as Tyvek) in the entire area of 
the power station. 
 
At present, as the density of the radioactive materials in the power 
station show a steady declining trend (since last September, the measured 
density of iodine has stayed below the detection limit), in order to 
further mitigate the inconvenience for the workers, we have decided to 
modify the operation regarding the charcoal filter masks and non-woven 
coveralls as described below. 
 
 · Charcoal Filter Masks 
   In the specific areas, the filter of the masks will be changed from 
   charcoal filters to dust filters which have the function of particle 
   collection. 
 
 · Non-woven Coveralls 
   In the areas specified as in the exemption of wearing full face masks, 
   the protective suites will be changed from non-woven coveralls to 
   general working wears. 
 
We have reported about this operational change to the Nuclear and 
Industrial Safety Agency at the Ministry of Economy, Trade and Industry 
and it confirmed the adequacy of the contents, we will start the operation 
from March 1 this year. 
 
We will continue our effort to keep the stability of the plants and to 
improve the work environment. 
 
<Contents of the operational change of wearing charcoal filter masks> 
 (1) Target of change from charcoal filter to dust filter 
   · Areas out of the buildings around Units 1 to 4 
 (2) Compliance items when changing the charcoal filter to dust filter 
   · Confirm that there is no abnormal signs by conducting observation 
     under Article 140 (water level and temperature of the spent-fuel pool) 
     and Article 143 (subcriticality observation) of the safety rules 
   · Define the difference of the mask filters depending on the mask 
     rental places by posting notices etc. 
   · In preparation for unforeseen troubles, necessary amount of charcoal 
     filters must be stocked at each Main Anti-earhquake Building and 
     lounge. 
   · Notice by advanced education etc. 
 
<Contents of the operational change of wearing non-woven coveralls> 
 (1) Target of change from non-woven coveralls to general working wears 
   · In the cars which connect directly the outer area of 1F site and 
     buildings in 1F such as the Main Anti-earthquake Building etc., in 
     the cars which connect directly the Main Anti-earthquake Building and 
     Service Buildings of Units 5 and 6, and while moving from the cars to 
     the Main Anti-earthquake Building and Service Buildings of Units 5 
     and 6 
   · While moving to the main gate for the procedures of entrance etc. 
 (2) Compliance items when changing non-woven coveralls to general working 
     wears 
   · Measurement of internal pollution of the cars for transportation 
     (ensure that the measured figures are below the screening levels) and 
     sheet curing 
   · Posting notices to enable recognition of the cars which workers in 
     the general working wears 
   · Periodical measurement of internal pollution of the cars for 
     transportation, confirmation of proper sheet curing, and other 
     necessary measures 
   · Notice by advance education etc. 
 
○ Appendix 
 (1)Mask with charcoal filter requirement area (PDF 296KB) 
 (2)Comparison of Mask with charcoal and dust filter (PDF 31.1KB) 
 (3)Change of rules for general working wear (PDF 19.3KB) 
 
 
○ Reference 
· Result of measurement of aerial density of radioactive materials at 1F 
                                                              (PDF 48.8KB)