LOS ANGELES >> The first radioactive fallout from Japan’s crippled nuclear plant reached Southern California early Friday, but the readings indicate levels far below a level that could endanger people, according to a diplomat.

The ambassador, who has access to United Nations radiation tracking of the Comprehensive Test Ban Treaty Organization, cited data from a California-based measuring station of the CTBTO.

Initial readings are “about a billion times beneath levels that would be health threatening,” the diplomat told The Associated Press. He asked for anonymity because the CTBO does not make its findings public.

U.S. government experts also insist there’s no threat to public health from the plume.

“Radiation is one of those words that get everybody scared, like ‘plague,”‘ said Dr. Jonathan Fielding, director of public health for Los Angeles County. “But we’re 5,000 miles away.”

The amount of any fallout that wafts across the Pacific Ocean to the U.S. coast will be so diluted that it will not pose any health risk, officials say. Wind, rain and salt spray will help clean the air over the vast ocean between Japan and the United States.

Nuclear experts say the main elements released are radioactive cesium and iodine. They can combine with the salt in sea water to become cesium chloride and sodium iodide, which are common and abundant elements and would readily dilute in the wide expanse of the Pacific, according to Steven Reese, director of the Radiation Center at Oregon State.

“It is certainly not a threat in terms of human health” added William H. Miller, a professor of nuclear engineering at the University of Missouri.

Earlier this week, the U.S. Environmental Protection Agency deployed extra radiation detectors throughout the country to allay public concerns. On Thursday, President Barack Obama said “harmful levels” of radiation from the damaged Japanese nuclear plant are not expected to reach the U.S.

Obama said he knows that Americans are worried about potential risks from airborne radiation that could drift across the Pacific. “So I want to be very clear,” he said. “We do not expect harmful levels of radiation to reach the United States, whether it’s the West Coast, Hawaii, Alaska or U.S. territories.”

(In Hawaii, Gov. Neil Abercrombie issued a statement Thursday that echoed the president’s comments.

“I want to reassure residents and visitors that the Nuclear Regulatory Commission, the highest authority on radiation in the nation, has indicated Japan’s nuclear emergency presents no danger to Hawaii,” he said. “Our state and county monitoring systems have not detected any increase in radiation levels, and based on all available information, state and federal experts do not anticipate any risk of harmful radiation exposure to our islands. We are open for business. Hawaii continues to be the world’s paradise.

The governor also said “residents do not need to take protective measures at this time.”)

The radiation stations will send real time data via satellite to EPA officials, who will make the data available to the public online. The monitors also contain two types of air filters that detect any radioactive particles and are mailed to EPA’s data center in Alabama.

That information, as well as samples that numerous federal agencies are collecting on the ground and in the air in Japan, also will be sent to the Department of Energy’s atmospheric radioactivity monitoring center in California, where teams are creating sophisticated computer models to predict how radioactive releases at Fukushima could spread into the atmosphere.

Inside Lawrence Livermore National Laboratory near San Francisco, scientists, engineers, and meteorological experts were analyzing those charts and maps to help policymakers predict where radioactive isotopes could travel.

“The models show what happens if the situation gets worse, if the winds change, or if it rains to predict what could happen,” National Nuclear Security Administration spokesman Damien LaVera said. “The Nuclear Regulatory Commission has said they see no radiation at harmful levels reaching the United States, and we’re not seeing anything that is inconsistent with that.”