GENEVA Winds are dispersing radioactive material from Japan's quake-crippled nuclear power plant over the Pacific Ocean, away from Japan and other Asian countries, the World Meteorological Organisation (WMO) said.
But the United Nations weather agency warned that although winds had blown nuclear particles offshore so far, weather conditions could change and it was closely monitoring satellite and other data in case the patterns shifted over land.
"At this point, all the meteorological conditions are offshore so there are no implications inshore for Japan or other countries near Japan," Maryam Golnaraghi, chief of WMO's disaster risk reduction division, told a briefing on Tuesday.
An explosion at Japan's quake-hit nuclear power plant sent out low levels of radiation, prompting some people to flee the capital Tokyo and others to stock up on essential supplies.
Separately, the World Health Organisation (WHO) said that evacuations and other measures taken by Japan to protect people in the stricken area were in line with recommendations based on public health expertise on nuclear emergencies.
"However, radiation-related health consequences will depend on exposure," the WHO said in a statement.
"Exposure in turn is dependent on the amount of radiation released from the reactor, weather conditions such as wind and rain at the time of the explosion, the distance someone is from the plant, and the amount of time someone is in irradiated areas," it said.
Japan was checking evacuees for contamination from radiation exposure and if necessary distributing supplies of potassium iodide to protect the thyroid and reduce the risk of cancer in the long term, according to the WHO.
"It is not a secret for any of you that the best experience in radiation and health expertise is probably in Japan," Dr. Maria Neira, director of WHO's department of public health and the environment, told reporters.
Japan, the site of the U.S. atomic bombing in Hiroshima and Nagasaki in August 1945 near the close of World War Two, often refers to its position as the only country to have suffered nuclear attacks when calling for abolition of atomic weapons.
The U.N. weather agency's assessment was based on models derived from data from three meteorological agencies in Japan, China and Russia, as well as other information, WMO spokeswoman Clare Nullis said.
"The meteorological conditions in the accident region have so far been mainly offshore, that is the winds have been dispersing materials introduced into the atmosphere from the accident site towards the open ocean, i.e., towards the northeast and to the east of the nuclear power plant at Fukushima," WMO later said in a statement.
"These conditions will fluctuate as weather systems develop and progress in the region over the coming period," it said.
Winds on Tuesday and Wednesday in the stricken area will mainly blow towards the northeast and east, but on Wednesday if particles are released in the lower levels of the atmosphere, "they will be westerly, they will be towards inland (Japan)," Golnaraghi told Reuters Television.
"So what it means is that depending on the concentration of the particles and depending on which level of the atmosphere they are issued, they could be taking a very different trajectory," she added.
(Additional reporting by Anne Richardson; editing by Mark Heinrich)