Dalek smoke

Dalek smoke was, according to some sources, what Daleks used to exterminate their enemies. The smoke would emerge from their gunstick. (TV: Dr. Who and the Daleks, Daleks' Invasion Earth 2150 A.D., et al.) The smoke was once described as a radioactive gas that would "[disintegrate] nervous cells upon mere contact." (COMIC: Daleks, invasión a la Tierra año 2150)

Many other sources suggested that gunsticks would instead shoot energy blasts (TV: Dalek, et. al) which would scramble the victim's insides. (TV: Remembrance of the Daleks) On one occasion, Dalek casings built on Earth used riot gas that resembled gun smoke. (TV: Revolution of the Daleks)