WASHINGTON -- The state of Alaska is considering adding additional radiation monitors in rural areas as a precautionary measure as federal nuclear officials continue to monitor Japan's failing Fukushima Daiichi nuclear power plant.
State and federal officials continued to emphasize that they did not expect harmful radiation from Japan to reach North America, including Alaska.
The state currently has monitors placed in Anchorage, Juneau and Fairbanks. The Alaska sites have been monitoring radiation for three years, as part of a nationwide sensor network that collects radiation readings and sends them to an EPA lab in Alabama.
Both the state and federal environmental officials are considering installing more "forward facing" monitors in rural parts of Alaska that would provide more advanced warning of radiation if it were to move toward population centers, said Greg Wilkinson, a spokesman for the Department of Health and Social Services.
The EPA's existing nationwide monitoring system, RadNet, continuously monitors the nation's air and regularly monitors drinking water, milk and precipitation for environmental radiation.
Neither state nor EPA officials could answer questions Tuesday on what happens if elevated radiation levels are detected, how quickly the data is analyzed and who is notified.
The EPA and other federal agencies were careful Tuesday to say that while they are being vigilant, they don't forecast alarming radiation levels anywhere in the United States.
"Right now, we're not expecting harmful levels of radiation to come to the U.S.," said Lara Uselding, a spokeswoman for the Nuclear Regulatory Commission.
As the nuclear crisis continued a fifth day and the Japanese nuclear plant spewed out more radiation on Tuesday, most experts in atmospheric science also said very little radiation could end up in the U.S.
"Even though the winds are blowing radiation out into the Pacific, they're (thousands of) miles from the U.S.," said Thomas Tenforde, president of the National Council on Radiation Protection and Measurements. "Plumes of radiation are going to get dispersed pretty widely. They're not just going to travel in a straight line to North America."
A statement from the Alaska Department of Health and Social Services and the Department of Military and Veterans Affairs said low-level winds were expected to carry radiation in Japan out to sea. "The only way the atmospheric radiation can reach the U.S. is through the high level jet stream. ... The jet streams over the Pacific are far south of Alaska for the next three days."
Dan Jaffe, a University of Washington Bothell atmospheric chemist who has studied pollution patterns crossing the Pacific from Asia for 20 years, said it's possible that radiation from a major meltdown of one or more nuclear reactors in Japan could reach Puget Sound, 4,800 miles away. But he said there would be no health risk.
"I can't imagine a scenario where the radiation release would be big enough to be a health hazard," he said.
But some said that trying to measure radiation could get tricky.
David Lochbaum, a nuclear engineer who directs the Union of Concerned Scientists' nuclear safety program, said that contamination levels are not necessarily lower the farther away people are from the source. In the Chernobyl disaster, some places 100 miles away had more radiation than other points 10 to 15 miles away. The distribution depends on how winds carry it and where rains wash it down, he said.
Ed Lyman, a physicist with the Union of Concerned Scientists global security program and an expert on nuclear plant design, said that there were some reports that Japanese officials hadn't handed out potassium iodide pills immediately. If true, that would be a concern, because people need to take the pills several hours before they're exposed to the radiation, he said.
As for the United States, Lyman said "it's unlikely, even worst case, that there would be significant health effects for people."
"No amount of additional radiation is a good amount, but I would think that would not be significant or anything for the U.S. to be concerned about," he said.
Major suppliers of pills that provide protection from radiation say they're out of stock due to panic buying, even though experts say that the Japanese nuclear catastrophe poses no health threat to Americans.
With thyroid cancer posing the most immediate health risk, Japanese officials made plans to distribute potassium iodide pills in an attempt to prevent it.
Troy Jones, president of nukepills.com in Mooresville N.C., said he has sold 6,500 orders of iodine pills in the last four days. In a normal four-day period, he said he'd sell only 100. He said most of the orders came from customers in Washington state, Oregon and California who want to protect themselves from Japanese radiation.
"Everybody thinks it's going to just land in their backyard in Malibu or something," Jones said.
On Capitol Hill, Democratic Rep. Ed Markey of Massachusetts called on the Obama administration to supply all U.S. citizens living within 20 miles of a nuclear plant with emergency pills.
The World Health Organization said that taking iodine tablets could be an important action to reduce the risk of thyroid cancer from radiation exposure. But it said that the decision should only be made by national health authorities.
Dr. Joe McLaughlin, the Alaska state epidemiologist, said Alaskans should not be taking the tablets. "While potassium iodide can protect the thyroid gland from harmful radiation, it can produce adverse side effects and should only be taken if exposure to considerably elevated doses of radiation is expected to occur," he said. "At this point, there is no immediate or anticipated indication that this will happen in Alaska."
By ERIKA BOLSTAD, ROB HOTAKAINEN and RENEE SCHOOF