A meltdown at one of Japan's failing nuclear reactors would likely spew radiation as far as the Bay Area but would not pose a health risk to residents, health officials said Monday.
With the crisis worsening following last week's devastating earthquake and tsunami, officials sought to reassure the public that a nuclear catastrophe would not be felt here.
Michael Sicilia, a spokesman for the California Department of Public Health, said the agency had been assured by the federal government that "the emergency presents no danger to California."
The Bay Area Air Quality Management District on Monday told residents that it does not expect radiation to reach the region unless the reactors’ concrete casing is breached or explodes.
If the casing does rupture, triggering a Chernobyl-style disaster, wind and other weather conditions would dictate the amount of radiation that would waft east over the Pacific Ocean to the Bay Area, BAAQMD spokeswoman Lisa Fasano said.
"It's something we’re watching," Fasano said. "As of right now, it's not an issue."
The potential for a serious meltdown grew larger Monday following an explosion at the Fukushima Daiichi Nuclear Power Station, according to reports. The explosion released radioactive material and may have have damaged the steel containment vessel of the station's No. 2 reactor.
Additionally, efforts to use seawater to cool the No. 2 reactor were reportedly failing, increasing the possibility that nuclear fuel could burn through steel casing and spill onto concrete below.
“That would mean a large radiological release into the environment,” Edwin Lyman, a physicist for the Union of Concerned Scientists, told reporters Monday. “It could potentially be large-scale, on the order of what we saw in Chernobyl.”
Lyman said it’s “quite likely” that radioactive fallout from such a disaster would reach the West Coast. Such a disaster could condemn thousands of Japanese citizens to thyroid cancer and other ailments, but Lyman said it was unlikely to cause harm on the West Coast because the material would arrive in relatively harmless concentrations.
No level of radiation is totally safe, but Lyman said the levels reaching California would pose a negligible threat.
“I think it’s unlikely, even in the worst-case scenario, that there would be significant health effects for people in the US,” Lyman said.
The amount of time that it would take the material to travel 5,000 miles from Japan to California would depend on whether it travels through the troposphere, the lowest layer of the earth's atmosphere, or on jet streams through the stratosphere, according to Kyaw Tha Paw U, a professor of atmospheric science at the University of California, Davis.
The radioactive particles and other pollutants would likely travel at 10 to 40 mph through the troposphere, or at upwards of 100 mph through the stratosphere, according to Paw U. That means the material could arrive within days following a nuclear meltdown.
“There’s a lot more mixing that occurs in the troposphere and, because of that, by the time it reaches the US it should be diluted quite a bit,” Paw U said. “If it’s a large enough explosion with lots of heat involved, it could reach into the stratosphere,” meaning the radiation would arrive faster and in higher concentrations.
An air monitor installed on the roof of the Bay Area Air Quality Management District's headquarters will help detect any spikes in radiation levels. It is part of a national network of monitors that detected radiation released by the Chernobyl disaster and from North Korean nuclear weapons tests, according to Fasano.
“The instruments capture things at a very fine level,” Fasano said.