Radiation monitors confirm no radiation levels of concern have reached the United States
by Joint Environmental Protection Agency/Department of Defense statement
March 18, 2011
WASHINGTON – The United States Government has an extensive network of radiation monitors around the country and no radiation levels of concern have been detected. The U.S. Environmental Protection Agency RadNet system is designed to protect the public by notifying scientists, in near real time, of elevated levels of radiation so they can determine whether protective action is required. The EPA’s system has not detected any radiation levels of concern.
In addition to EPA’s RadNet system, the U.S. Department of Energy has radiation monitoring equipment at research facilities around the country, which have also not detected any radiation levels of concern.
As part of the Comprehensive Nuclear Test Ban Treaty Organization’s International Monitoring System (IMS), the Department of Energy also maintains the capability to detect tiny quantities of radioisotopes that might indicate an underground nuclear test on the other side of the world. These detectors are extremely sensitive and can detect minute amounts of radioactive materials.
Today, one of these monitoring stations in Sacramento, California that feeds into the IMS detected miniscule quantities of the radioactive isotope xenon-133. The origin was determined to be consistent with a release from the Fukushima reactors in Northern Japan. The levels detected were approximately 0.1 disintegrations per second per cubic meter of air (0.1 Bq/m3), which results in a dose rate approximately one-millionth of the dose rate that a person normally receives from rocks, bricks, the sun and other natural background sources. This validates a similar reading of 0.1 Bq/m3, taken from March 16 through 17 in Washington State.
Xenon-133 is a radioactive noble gas produced during nuclear fission that poses no concern at the detected level.
These types of readings remain consistent with our expectations since the onset of this tragedy, and are to be expected in the coming days.
Following the explosion of the Chernobyl plant in Ukraine in 1986 – the worst nuclear accident in world history – air monitoring in the United States also picked up trace amounts of radioactive particles, less than one thousandth of the estimated annual dose from natural sources for a typical person.
As part of the federal government’s continuing effort to make our activities and science transparent and available to the public, the Environmental Protection Agency will continue to keep all RadNet data available in the current online database.
Please see www.epa.gov/radiation for more information.