Radiation levels in central Tokyo remained about four times higher than
normal Wednesday evening, while in areas close to the quake-striken Fukushima
nuclear power plant they remained high but still below levels that would pose a
threat to human health.
The Tokyo Metropolitan Government said Wednesday on its website that radiation
levels in downtown
Tokyo
stood
at an average 0.146 microsievert an hour around 1200 GMT, compared with the
0.035 microsievert an hour a person would typically be exposed to in central
Tokyo
due
to background radiation.
The radiation level started picking up from Monday morning after rainfall in the
area, which helped drop radioactive materials such as iodine-131 from the sky,
officials have said.
A chest X-ray typically exposes the patient to a radiation dose of around 100
microsieverts, according to the Radiological Society of North America.
Separately,
Fukushima
Prefecture
said
on its website that it measured radiation of 5.21 microsieverts at 1200 GMT
Wedneday in
Fukushima
City
,
about 60 kilometers northwest of the nuclear power plant. It said it detected
1.54 microsieverts an hour in Koriyama City, around 60 kilometers west of the
plant, and 1.62 in Iwaki City, about 40 kilometers southwest of the plant,
around 1200 GMT. Normal levels at these locations range between 0.04 and 0.06
microsieverts.