Survivors of the blast need to take protective measures against the radioactive fallout. Fallout, as you have learned, is radioactive material. Radioactive material deposited in undesired locations is called radioactive contamination.

The difference between contamination and radiation is important to understand. You can be exposed to radiation without becoming contaminated.

When you are exposed to radiation, the radiation does its damage, expends all its energy, and is gone.

If you carry contamination on your clothes or body, the material continues to emit radiation as long as it is radioactive.