Radiation wafting toward the U.S. from stricken nuclear reactors in Japan poses far less threat than 1950s-era atomic weapons testing or the 1986 Chernobyl accident, weather and public health experts said.
The radiation plume from the reactors is moving northeast over the Pacific, the Austrian Meteorological and Geophysics Center reported on its website. Weather patterns over the ocean will bring it to the U.S. today or tomorrow, said Jeff Masters, co-founder of Weather Underground Inc. in Ann Arbor, Michigan.
Even in a worst-case scenario of a reactor meltdown at the Fukushima plant, dilution of the radiation by the Jet Stream and Pacific winds is likely to prevent harmful radiation from reaching the West Coast, said Thomas McKone, an adjunct professor in the Department of Environmental Health Sciences at the University of California, Berkeley.
“There is enormous dilution between Japan and here,” said McCone, who is also a senior staff scientist at the U.S. Energy Department’s Lawrence Berkeley National Laboratory. “I don’t think there can be any measurable health impacts in California.”
After Chernobyl, experts found no measurable health effects to humans from direct radiation exposure outside of a 50-mile radius, according to McKone. Bombs tested in the U.S. in the 1950s and 1960s released much more radiation than is coming from the Fukushima plant, crippled by Japan’s largest earthquake on record and the resulting tsunami, Masters said.
“It is hard to compare a bomb going off up in the air over Nevada with something 5,000 miles away in Japan at the surface,” Masters said. “The exposure was far, far greater from the Nevada test explosions.”
More than 500 atmospheric nuclear weapons tests were conducted worldwide prior to 1963, according to the U.S. Centers for Disease Control. The U.S. government, in a study that included the CDC and the National Cancer Institute, estimated in 2006 that anyone living in the lower 48 states after 1951 had been exposed to some fallout.
About 50 deaths have been directly attributed to radiation from Chernobyl, while 4,000 may eventually die from the side effects of exposure, mostly from cancer or related disease, according to a 2005 World Health Organization report.
Radiation particles released into the air from the Japanese reactor vessels and spent-fuel ponds are moving southeast before extending in a northeasterly pattern over the Pacific. Particles may start moving northwest as the winds are expected to shift.
Particles in Plume
Radioactive barium, cesium, iodine and tellurium have been detected in the plume, the Austrian agency said. A partially dispersed cloud passed through the Tokyo area yesterday, according to the Austrian center.
“Whether it will be even detectable” when it arrives in the U.S. “is a question in my mind because of the amount of dispersion that goes on over at least a 5,000-mile track that that stuff had to take,” said Masters. “It just wasn’t emitted in large enough quantities to be a threat to human health and it may not even be detectable.”
That hasn’t stopped fear from spreading, said Kirk Smith, a professor at the University of California School of Public Health at Berkeley who has studied the fallout from Chernobyl and the health risks of radiation.
Smith said some of his students have discussed moving to Denver to get away from fallout, unaware that exposure to naturally occurring daily radiation is higher in mountainous Colorado than at sea level in California.
“The radiation you get on a flight to Denver would be far higher than anything that could come from Japan,” Smith said.
“People are wasting their money and there is no reason to do it because there is no radiation level sufficient to merit this,” Shields said. The Johns Hopkins Office of Critical Event Preparedness and Response warned that the drug may have serious side effects for people with certain allergies and kidney and thyroid problems.
The state of California and Los Angeles County may put up additional radiation monitors to assess the situation, said Chris Ipsen, division chief for the city of Los Angeles’s emergency management department.
The best chance to detect the radiation in California may come next week when the plume mixes with storm systems coming ashore along the coast, said Masters, who before founding Weather Underground tracked acid rain and air pollution.
“That would be the most likely time for it to get to the ground and be detectable,” Masters said. “But again, the amounts are going to be pretty darn small.”
Tracking a plume isn’t an exact science, said Sue Haupt, scientific program manager at the National Center for Atmospheric Research in Boulder, Colorado, and a meteorology professor and researcher at Pennsylvania State University.
The mapping requires computer models, and variables include the height of the release as well as the weather patterns it encounters.
Weather over the Pacific can be complicated, said Jim Andrews, a senior forecaster for AccuWeather Inc. in State College, Pennsylvania.
The Jet Stream is always dipping and buckling, so anything being carried on the wind could be blown over a wide area. In addition, winds at different levels of the atmosphere blow in different directions, which may shear apart a cloud of radiation, he said.
“Certainly the weather is going to play a large factor, otherwise the size of the particle will dictate how long it is going to take to settle” to the surface, said David Stauffer, a meteorology professor at Penn State. “The larger ones will fall out quicker than the smaller ones.”
“Radiation is odd, and it has this terrible history of being born in secrecy and war,” Smith said. “We are capable of measuring extremely small amounts, but just because you can measure it doesn’t mean it’s dangerous.”
To contact the reporters on this story: Brian K. Sullivan in Boston at firstname.lastname@example.org; Bradley Olson in Houston at email@example.com; Mark Chediak in San Francisco at firstname.lastname@example.org