The type of radiation that can only travel a short distance (a few feet) in air is alpha radiation.

Here's why:

* Alpha particles are relatively large and heavy, consisting of two protons and two neutrons. This makes them interact strongly with matter, including air molecules.

* These interactions cause alpha particles to lose energy quickly, limiting their range to only a few centimeters in air.

While other types of radiation like beta and gamma can travel further, alpha radiation is the least penetrating and poses the greatest risk if ingested or inhaled.