Related Rule
Israel
Practice Relating to Rule 75. Riot Control Agents
Israel’s Manual on the Rules of Warfare (2006) states:
Tear gas. Apparently, even the tear gas used by the police to disperse demonstrations is a chemical weapon and thus prohibited under the Protocol, despite its relatively minor effect. An absurd situation results in which demonstrators are “endangered” by tear gas whereas fighters going out to battle are protected from it. 
Israel, Rules of Warfare on the Battlefield, Military Advocate-General’s Corps Command, IDF School of Military Law, Second Edition, 2006, p. 19.
The Manual on the Rules of Warfare (2006) is a second edition of the Manual on the Laws of War (1998).