UPDATE • Agency insists amount still 'below levels of concern'
On Friday afternoon, the U.S. Environmental Protection Agency reported that radiation from the damaged nuclear power plant in Japan had been detected in Californa and Washington.
The agency said the amounts were well below any level that could cause harm.
In a Friday afternoon statement, the EPA said that xenon-133 had been detected in Washington on Wednesday and Thursday, and in California on Friday. The origin was determined to be a release from the Fukushima reactors in Northern Japan.
'Xenon-133 is a radioactive noble gas produced during nuclear fission,' the statement said, 'that poses no concern at the detected level.'
According to the statement, the levels were 'approximately one-millionth of the dose rate that a person normally receives from rocks, bricks, the sun and other natural background sources."
The announcement is the first time the EPA has said any amount of Japanese radiation has been detected in America. Earlier in the day, the agency issued a statement which said no radiation had reached the country from Japan. 'As of noon (EDT) EPA's RadNet radiation air monitors across the U.S. show typical fluctuations in background radiation levels,' the statement said.
The EPA operates a series of radiation sensors across the country known as RadNet. Some news outlets are reporting slight increases in radiation being detected from Alaska to California. But according to the Friday statement.
Experts say radiation from the plant is being dispersed as the winds carry it across the Pacific Ocean. At least three reactors at Japan's Fukushima Daiichi nuclear plant were damaged by the March 11 9.0-magnitude earthquake. One of the reactors has become so hot, crews trying to contain the radiation had to back off for several hours as water was dropped by military helicopters and pumped in from fire hoses.
Radiation has been leaked from the reactor and radioactive gas has been released into air to relieve pressure.
There is no estimate on when the plant will be repaired and stop releasing radiation.