Trace radiation could reach West Coast
Some simulations now show traces of radiation from Japan potentially reaching across the Pacific to the U.S. West Coast by Friday, but even if it did, the radiation amounts would be so tiny that they would represent no health threat, experts say.
"Our six-day forward plume simulation shows most of it misses us," said Menas Kafatos, founding dean at Chapman's Schmid College of Science, whose research group generates wind and weather forecasts from satellite data.
None of the simulations include data on actual radiation amounts; instead, they model expected wind patterns.
Radiation detectors in Southern California, including one in Anaheim, also have picked up no signs of radiation from Japan, according to the South Coast Air Quality Management District, which is now posting daily updates on radiation levels on its web site.
The agency says it is posting the updates because of public concern about radiation. The U.S. Environmental Protection Agency is also expanding its nationwide network of radiation detectors, called Radnet.
Any radiation arriving on the West Coast would be so diluted that it would be difficult to distinguish from background levels, said Charlie Zender, a UC Irvine atmospheric physicist.
Although dust and pollution from Asia are known to reach the West Coast, the dilution factor is significant.
"When pollutants are transported, they are diluted on the order of a factor of 1,000," Zender said. "If you take the maximum emissions occurring around the power plant and divide by 1,000, you get levels that are well below background."
Both Zender and Kafatos said a far larger release of radiation would be needed in Japan to be a factor here; Zender said it would require an improbable combination of a "worst case" scenario in Japan and just the right weather conditions over the ocean.
The Nuclear Regulatory Commission also has said it expects no harmful radiation to reach the United States from crippled Japanese reactors.
Still, residents in California and other states have made a run on potassium iodide tablets, which protects thyroid glands against one type of radiation.
Health experts say taking potassium iodide tablets is unnecessary without immediate risk of exposure, and could produce unwanted side effects.
Fears were likely stoked by a bogus map carrying the NRC logo that is circulating on the Internet, and purports to show large amounts of radiation headed our way. An NRC spokeswoman said the agency is aware of the map, and that it is a fake.
Japanese officials continued to fight for control in a nuclear crisis involving several reactors at the Fukushima Daiichi power plant, damaged by last week's massive earthquake and the resulting tsunami.