In an update from the Washington State Department of Health, officials say since the failure of the power plants in Japan, radiation levels in Washington have not climbed above normal nor do they expect them to pose a threat.

From the press release:

Several factors play a role in protecting Washington from the release of radiation occurring at the damaged reactors in Japan:

- Most of the radioactive material is contained at the damaged plants; even if radioactive material reaches the upper atmosphere, it would not reach Washington in concentrations high enough to cause a health risk.
- The radioactive material that was released did not reach the upper atmosphere where it could be carried toward North America by the jet stream in amounts that would cause public health impact.
- The fires and explosions at the Japanese reactors have not been as intense as the Chernobyl accident. Radioactive material ejected into the jet stream from Chernobyl did reach Washington in small amounts. - - Even after the Chernobyl disaster, protective action was not needed in our state, and the Japan incident is much smaller than Chernobyl.
- Even if radioactive material is released in Japan and reaches the jet stream, it would take several days to get here because the nuclear plants are about 5,000 miles from our state. In the time it would take to cross the Pacific, it would mix with lots of air as it’s blown in the wind (thus diluted); rain would wash some of the material from the air into the ocean.
- Radioactive decay, especially for short half-life radioactive materials such as iodine-131, would substantially reduce the amount of the radioactive material that could reach here.

For these reasons, it’s unlikely that we will see an increase in background levels of radiation in Washington. Even if a small amount of radiation did reach the state, it would be well below levels that would pose public health concerns.