Can nuclear fallout reach the US?

Yes. Nuclear fallout from a detonation or major reactor accident overseas can reach the U.S. if radioactive particles get carried high into the atmosphere by global winds, especially the jet stream.

What matters most: by the time it crosses an ocean, it is usually very diluted and much of the short-lived radiation has decayed. In past events like Fukushima and Chernobyl, trace amounts were detected in the U.S., but typically at levels far below public health limits.

Bottom line:

• A single foreign incident: fallout can arrive, but usually not as a dangerous health threat in the U.S.
• A large nuclear war: fallout could be part of a much bigger global crisis, with severe climate and food-supply impacts.

The U.S. tracks airborne radiation through EPA RadNet and related monitoring systems.