2 days after a Typhoon hit Japan, and TEPCO admitted large radiation releases due to the storm, radiation levels spike in Hawaii.
Keep in mind, this will travel to mainland USA and cross over in a day to 4 days.
Another storm is headed to Fukushima for a 1 -2 punch. This will extend the danger time frame.
Basic good radiation practice here:
1) Stay out of the rain
2) Dose up with anti-oxidants
3) Run your multiple HEPA filters all the time
4) Get a Geiger and learn how to use it
Here is my chart showing relative danger levels of radiation, 150 is pretty bad. That is where Hawaii is now.