Radioactive substances spewed from a damaged Japanese nuclear plant were carried to Europe through the United States by a jet stream, Japanese researchers said, Jiji news agency reported Wednesday.
A Japanese research group led by Toshihiko Takemura, associate professor at Kyushu University, tracked the flow of leaked radiation from the Fukushima Daiichi nuclear power plant through a computer simulation, dpa reported.
Since the plant was crippled by the March 11 earthquake and resulting tsunami, it has leaked radiation into the environment.
Since the density of radioactive substances reaching the United States and Europe was 100 million times less than that around the Fukushima plant, the effects are limited there, the researchers said.
Radioactive substances rose to about 5 kilometres when a low pressure system passed over eastern Japan on March 14-15, the researchers said.
The substances were blown eastward by a jet stream traveling at a speed of some 3,000 kilometres a day, arriving on the US West Coast on March 18, in Iceland on March 20, and many other European countries on March 22, the researchers said.
They said radioactive substances were indeed detected in each of the places on the estimated arrival dates.