Readers ask: Will radiation from the Japan quake and tsunami affect the Hawaiian Islands by May 2011? Should we cancel trips to Hawaii for our families?
Science answers: You don't need to cancel your trip to Hawaii. Any released material must travel over 6000 kilometers to reach the Hawaiian Islands. The prevailing winds are indeed heading east over the Pacific from Japan, but the vast majority of radioactive material will rain down into the ocean within a few hundred kilometers of the nuclear plant.
Which isn't to say that radiation won't be detectable in Hawaii. After all, this is what makes radioisotopes so useful for biological research: They are detectable in even the most minuscule (and safe) amounts. A trace amount of radioactive xenon-133 has already arrived in California at a level one-millionth the dose received from natural sources like bricks.
Only gases such as xenon are likely to make it that far, and only at such highly dilute concentrations. For the less volatile radioisotopes to travel, they must ride on particles that are heavier than air. Gravity will take care of those.
In an address from the White House, President Barack Obama reassured residents of Hawaii and the U.S. west coast that no precautions are needed. But there's no harm in keeping an eye on the radiation info page maintained by the Centers for Disease Control and Prevention.