The hydrogen explosions which occurred at the Fukushima I Nuclear Power Plant on 12, 14 and 15 March 2011, spread radioactive materials into the air all across Fukushima Prefecture, and beyond. National and prefectural responses languished, and immediate radiation measurements in schools and kindergartens were neglected. The signs of danger were first recognized by parents and teachers.
MEXT (Ministry of Education, Culture, Sports, Science and Technology) announced on 19 April, that the temporary standard value of radiation exposure for schools was 20μSv per year. The level was arbitrarily raised, the government simply increased the allowable radiation dosage by twenty times, from 1μSv per year to twenty, including children. Fukushima Parents finally confronted the government with the slogan "Protect children from radiation".