(A) “Gas mask” means any self-contained oxygen breathing apparatus using oxygen or air in suitable containers that enable their wearers to live in atmospheres containing less than sixteen per cent oxygen and poisonous gases in excess of two per cent by volume and having been approved by the United States bureau of mines for use in irrespirable atmospheres.

(B) Every political subdivision which operates a fire department shall provide at least two gas masks for each fire station and shall further provide that the chief of the fire department give adequate instructions to each member of the fire department in the use of such gas masks.