The radiation that's leaked from the disabled reactors at Japan's earthquake-damaged nuclear power stations does not pose a health risk to Canadians on the Pacific coast, officials say.

"Health Canada has advised us that at the present time the current radiological activity at a facility in Japan is expected to pose no health risk to British Columbians," British Columbia's safety minister Rich Coleman said in a statement released Sunday.

Nevertheless, the federal government is warning Canadians not to travel within 20 kilometres of the Fukushima facility, as well as to avoid non-essential travel in areas hit by the tsunami.

The U.S. Nuclear Regulatory Commission also said Sunday it did not expect to experience "any harmful levels" of radiation in Hawaii, Alaska or its Pacific coast.

The World Health Organization says it believes that global health risks from the troubled reactors seem fairly low for now, and that winds are likely to carry any radioactive contamination out to the Pacific Ocean.

WHO spokeswoman Christy Feig said there was no request to mobilize radiation experts known as REMPAN (Radiation Emergency Medical Preparedness and Assistance Network) set up after the Chernobyl meltdown.

Japanese officials say while workers are still struggling to cool down three reactors at the Fukushima plant that no longer have cooling systems, the radiation threat is low.

Nevertheless, they have ordered anyone living within 20 kilometres of the Fukushima nuclear power plant to evacuate the area as a precaution. That order is thought to affect around 140,000 people.

Though most of the general Japanese population should be spared significant health problems from any partial meltdowns at the reactors, there have been two hydrogen gas explosions at two reactors, which have released small amounts of radioactive particles in the atmosphere.

Those explosions appear to have exposed some workers at the plant to dangerous amounts of radiation. Three workers have now come down with radiation sickness, with symptoms including nausea, fatigue, vomiting, and diarrhea.

Their prognosis is uncertain since it's unclear how much radioactive material they were exposed to and for how long. If they develop more serious symptoms in the next few weeks, it could be a sign they experienced potentially fatal damage to their internal organs.

Japan has rated the Fukushima accident as a 4 on the seven-point International Nuclear and Radiological Event Scale, meaning it's an accident with "local consequences."

Chernobyl, the worst nuclear disaster to date, was rated a 7. The partial core meltdown at Three Mile Island in 1979 was rated a 5. The radiation release from the Chernobyl disaster was about a million times the amount released from Three Mile Island.