One of my less tasteful friends made the comment that Japan had to wait sixty years to return the favor of Hiroshima and Nagasaki.
I suppose, in a sense, he was correct.
There's been much in the news about having to deal with potential radioactive fallout from the Fukushima powerplant's possible meltdown. Unit One and Unit Three have already been rocked by explosions and the threat to the remaining reactors is growing. Some news articles contend that a meltdown is in progress, or a partial meltdown has already occurred.
If a meltdown does, or has, happened fallout in the form of heavy and light particles will rise into the atmosphere and travel across the Pacific Ocean on air currents.
Maps tracking fallout patterns to the west coast of North America as well as an excellent article can be found here at Modern Survival Blog. It has updates on the developing situation and pertinent information regarding personal preparation.
The good news is many of the heavier particles will drop out of the airstream over the Pacific and probably not make landfall in North America.
The bad news is the more fine, lighter particles, will travel farther before dropping out of the airstream. These will make landfall, possibly as far as Colorado, before dropping out.
The good news is that if the quantity of fallout is small, it will be so widely scattered as to essentially disappear into normally present background radiation sources.
And there's where the hitch is.
How much fallout North America will have to deal with is also a question that is, pardon the pun, up in the air. If we use Chernobyl as a representation of a possible scenario, an estimated 50 TONS (100,000 pounds) of nuclear fuel "evaporated" in the explosion and fire. Much of it landed in the area immediately surrounding the plant, and even more in the areas downwind in the Ukraine. But significant materials remained in the air so that it traveled and triggered radiation detectors in Western Europe, and even the Eastern US.
Remember, Chernobyl was a single reactor. Japan is dealing with the potential for multiple reactor failures.
What most people should be concerned with are Cesium 137, Strontium 90, and Iodine 131.
Cesium 137 is released by reactor accidents and presents a significant health risk in that it distributes itself through the soft tissues and is a strong source of ionizing radiation. Ionizing radiation can destroy your DNA and disrupt the body's cellular functions. Half life is 30 years, and the primary path into the body is ingestion and inhalation.
Strontium 90 is not likely to be released by a reactor accident, BUT it can be. Strontium 90 mimics calcium and is readily taken up by the body. Half life is approximately 30 years and the primary path into the body is ingestion and inhalation.
Iodine 131 is readily absorbed by the thyroid gland as it mimics the non-radioactive form of iodine which is needed for the production of certain hormones. Half life is 8 DAYS, not years, so that is a sort of a blessing. Primary path into the body is ingestion.
Three simple steps to protect yourself from ingesting these elements:
Wash all produce thoroughly with clean running water.
Wash all cans of food prior to opening them to avoid potential contamination from radioactive dust that may have settled on the cans. (Remember your pets, too!)
Avoid drinking from open water sources (streams, ponds, etc.).
Much has been said about purchasing Potassium Iodine (Iodate) in order to flood your thyroid with the needed element to prevent the uptake of the radioactive form of Iodine. Apparently, there are rumors of panic buying.
If you find yourself unable to locate iodine supplements, there are natural sources that are readily available.
Laver (Nori in Japan. It's that greenish/black paper-like wrap around makizushi )
Seafood (fish and shellfish)
Another strategy is eating peanuts, soybeans (and related like Tofu), canola oil, cassava, strawberries, pine nuts, millet, pears, peaches, spinach, bamboo shoots, sweet potatoes, and anything in the Brassica family. These are known to inhibit the absorption of iodine by the thyroid.
This last suggestion is a stop gap measure only to be considered if you do not have access to a source of iodine.