The intentional or accidental release of radioactive material which poses a threat to human health and safety. The most likely scenario involves what is commonly referred to as a "dirty bomb" or "radiological dispersion device (RDD)." An RDD is the use of common explosives to spread radioactive materials over a targeted area. It is not a nuclear blast. The force of the explosion and radioactive contamination will be more localized. While the blast will be immediately obvious, the presence of radiation will not be clearly defined until trained personnel with specialized equipment are on the scene. Radiation may also be released through an accident or spill involving radioactive materials used in medical or industrial applications. Depending upon atmospheric conditions and wind direction, a large release of radiation from the Indian Point Nuclear Power Plant has the potential to affect NYC and surrounding areas.

The primary concern in an emergency involving the release of radiation is limiting exposure through distance or shielding.