Measuring radiation levels accurately is difficult for laypersons and they shouldn't panic if their devices show much higher levels than the figures announced by the government, radiation experts say.
"Cheap and easy-to-handle devices sold on the Internet can sometimes show abnormally high radiation levels. Figures change on such devices even if you hold them still, and thus margins of error by 20 or 30 percent would be no surprise," said Genichiro Wakabayashi, a professor of radiology at Kinki University.
"The important thing is to keep monitoring at the same place over a long period of time to check changes in radiation levels. Thus, the figures from the Education, Culture, Sports, Science and Technology Ministry are, after all, reliable," he said.