Government experts in the United States are keeping a close eye on any radioactive particles that could travel from Japan, and they may already be seeing trace amounts.
A diplomat who has access to radiation tracking by the U.N.'s Comprehensive Test Ban Treaty Organization told The Associated Press in Vienna that initial readings show tiny amounts of radiation have reached California. But it's not dangerous in any way - "about a billion times beneath levels that would be health threatening," the diplomat said, speaking on condition of anonymity because the organization does not make its findings public.
U.S. government experts also insist there's no threat to public health from the plume, but they are still closely monitoring the situation with detection monitors deployed along the West Coast.
The new California reading came from a measuring station of the Comprehensive Test Ban Treaty Organization, and the monitor was apparently located in Sacramento.
"Radiation is one of those words that get everybody scared, like `plague,'" said Dr. Jonathan Fielding, director of public health for Los Angeles County. "But we're 5,000 miles away."
The amount of any fallout that wafts across the Pacific Ocean to the U.S. coast will be so diluted that it will not pose any health risk, officials say. Wind, rain and salt spray will help clean the air over the vast ocean between Japan and the United States.
Nuclear experts say the main elements released are radioactive cesium and iodine. They can combine with the salt in sea water to become cesium chloride and sodium iodide, which are common and abundant elements and would readily dilute in the wide expanse of the Pacific, according to Steven Reese, director of the Radiation Center at Oregon State.
"It is certainly not a threat in terms of human health" added William H. Miller, a professor of nuclear engineering at the University of Missouri.