Related Rule
Practice Relating to Rule 75. Riot Control Agents
Belgium’s Law of War Manual (1983) states that “it is uncertain whether … chemical products that do not cause widespread, long-term and severe damage to the environment” are covered by the prohibition on the use of asphyxiating and other analogous gases. 
Belgium, Droit Pénal et Disciplinaire Militaire et Droit de la Guerre, Deuxième Partie, Droit de la Guerre, Ecole Royale Militaire, par J. Maes, Chargé de cours, Avocat-général près la Cour Militaire, D/1983/1187/029, 1983, p. 38.