A screen capture of RadNet sensor locations from 2 p.m. Friday. Light blue icons indicates sensors "under review."
Federal officials said today that a Sacramento radiation detector found a miniscule amount of a radioactive isotope that is consistent with material released from a stricken Japanese nuclear reactor complex.
A joint Environmental Protection Agency and Department of Energy press release says the detector found 0.1 disintegrations per second per cubic meter of air of xenon-133, a radioactive isotope produced during nuclear fission.
It's hard to comprehend how little radiation that is. For comparison, the press release said that amount is equivalent to one-millionth the dose of radiation a person normally receives from background sources, like rocks, bricks and the sun.
The press release said similar readings were detected in Washington state on March 16 and 17.
The federal government has several ways to monitor airborne radiation levels. These readings came from the Comprehensive Test Ban Treaty's International Monitoring System, which is used to detect even very tiny radioactive releases that might indicate weapons testing anywhere in the world.
The EPA also maintains a radiation detection network called RadNet, which has sensors spread out nationwide.
In response to intense interest from the press and the public, the EPA has set up web pages for people to monitor radiation data in their areas.
The site includes general information about the radiation tracking, and links for monitoring specific cities.
Here are the links for California:
Scientists and government agencies uniformly say they don't expect dangerous levels of radiation to reach the United States, but that they do expect some measurable traces.
Today's press release said that sensors in the United States also picked up trace amounts of radioactivity in the aftermath of the Chernobyl disaster in 1986.