The international agency that monitors atomic radiation says that the Western United States and Canada could see some increased levels as the radiation cloud emitted in North Korea passes north of Hawaii and towards the Aleutian islands.
But some of the highest levels from the still-secretive incident are being measured in Asia.
Melissa Fleming, spokeswoman for the International Atomic Energy Agency said that radiation levels in Japan after a nuclear leak in North Korea have measured at 200 times normal background radiation and though they are dropping, levels on surfaces remain at an increased measurement.
In Japan, levels of 120-150 time normal background radiation have been measured, also with surfaces retaining precipitation.
Fleming said that as the cloud travels, it will move past Hawaii and toward the Aleutians, affecting the Western United States and Canada.