Tear gas is used both by police for crowd control and by individuals for self-defense. There are three main forms of tear gas:

  • CN (chloroacetophenone)
  • CS (chlorobenzylidenemalononitrile)
  • OC (pepper spray, Oleoresin capsicum)


  • Contain any doorway exit of the affected area with 4-6 mill plastic.
  • Do not let people enter the affected areas, as the contamination is easily spread.
  • If affected areas are served by HVAC, shut down immediately. (Any HVAC units servicing the area should be shut down at the beginning of Police Activity.)
  • If an elevator is in the immediate area, shut it down.
  • If multiple canisters have been fired into a unit that has a common hallway, expect secondary contamination in the hallway and adjoining spaces.
  • Apply PurAyr treatment to effected area and HVAC system, no further decontamination steps are necessary.