In March and April, Kanagawa local government measured radiation in the fallout plume such as rain and dust and published the data on Ministry of Education, Culture, Sports, Science and Technology’s HP, but it contained 14 errors and was not revised for 6 months.
It was the data from 3/20~4/1, of Chigasaki shi.
For example, during 3/21~3/22, they originally published radioactive Iodine-131 = 340 Bq/m2, but it was actually 9,500 Bq/m2,which is 28 times higher than original.
For 6 months, believers were left exposed.
(Source)