The U.S. Environmental Protection Agency is doubling Hawaii’s radiation monitors to four and adding detectors in Guam, the Northern Mariana Islands and Alaska, even as it downplays the potential danger from Japan’s failing nuclear reactors.

The agency Tuesday echoed the Nuclear Regulatory Commission in saying it does not “expect to see radiation at harmful levels reaching the U.S.”

A United Nations weather forecast, meanwhile, predicts that a “radioactive plume” will reach the Aleutian Islands today and hit Southern California late tomorrow, the New York Times reported.

The forecast shows the plume passing to the north of Midway and Hawaii, the Times said. Some experts have said the distance traveled by the radiation over the ocean would cause it to disperse with little risk to humans.

The chairman of the NRC briefed President Barack Obama yesterday on what the White House called “the deteriorating situation” at the Fukushima power station.

Hawaii currently has two radiation monitoring stations, one each on Oahu and the Big Island. State health officials said they will put the two new monitors on Oahu’s North Shore and Kauai.

“The agency decided out of an abundance of caution to send these deployable monitors in order to get some monitors on the ground closer to Japan,” said Jonathan Edwards, director of EPA’s radiation protection division.

The two new “RadNet” detectors are expected to be in place in Hawaii by week’s end, state Health Department spokeswoman Janice Okubo said. She added yesterday that radiation levels in Hawaii have not increased.

“We have not seen any change,” she said. “All background normal levels.”

Honolulu officials sought to reassure the public yesterday that measures are in place to handle possible radiation fallout while re-emphasizing that the chances of danger are minimal.

The Honolulu Emergency Services Department conducted its monthly testing of its Metropolitan Medical Response System, which includes a van and portable monitors about the size of a car battery that can be used for chemical, biological, radiological, nuclear and explosives detection.

Testing conducted yesterday at Kakaako Waterfront Park did not show any elevated radiation level, said Dr. James Ireland, director of the Honolulu Emergency Services Department.

Ireland said the department also oversees a “huge cache” of potassium iodide, which can be administered to prevent iodine radiation from accumulating in an affected person’s thyroid gland.

The Centers for Disease Control and Prevention maintains a national strategic stockpile of medicine that would be distributed in the event of radiation fallout, the state Heath Department said.

“So our cache would be used potentially to be the initial distribution pending (those CDC supplies) arriving here,” Ireland said.

Radioactive caesium and plutonium are two other potential concerns, and Ireland said there are other agents that protect against ingested radiation that are also cached in the state.

Some experts have raised concern that if there is a nuclear meltdown, larger amounts of radiation could be injected high into the atmosphere and be carried to Hawaii on the jet stream.

“I think there is a risk, certainly (to Hawaii and the West Coast),” said Paul Carroll, program director at the Ploughshares Fund.

In the case of a catastrophic release of radiation, Hawaii would have three to four days to respond, Jeff Eckerd, acting program manager for the Indoor and Radiological Health Branch of the state Health Department, said at a state Senate briefing yesterday. That is based on the direction of the jet stream for the next three to five days and the fact that Hawaii is 4,000 miles away, he said.

———

The Associated Press and Star-Advertiser reporter Leila Fujimori contributed to this report.