(19.9 in × 18.9 in) canvas hood treated with chlorine-absorbing chemicals, and fitted with a transparent mica eyepiece. macpherson presented his idea to the british war office anti-gas department on may 10, 1915; prototypes were developed soon after. the design was adopted by the british army and introduced as the british smoke hood in june 1915; macpherson was appointed to the war office committee for protection against poisonous gases. more elaborate sorbent compounds were added later to further iterations of his helmet (ph helmet), to defeat other respiratory poison gases used such as phosgene, diphosgene and chloropicrin. in summer and autumn 1915, edward harrison, bertram lambert and john sadd developed the large box respirator. this canister gas mask had a tin can containing the absorbent materials by a hose and began to be issued in february 1916. a compact version, the small box respirator, was made a universal issue from august 1916. in the first gas masks of world war i, it was initially found that wood charcoal was a good absorbent of poison gases. around 1918, it was found that charcoals made from the shells and seeds of various fruits and nuts such as coconuts, chestnuts, horse-chestnuts, and peach stones performed much better than wood charcoal. these waste materials were collected from the public in recycling programs to assist the war effort. the first effective filtering activated charcoal gas mask in the world was invented in 1915 by russian chemist nikolay zelinsky. gas mask for horses 1916, russian soldiers also in world war i, since dogs were frequently used on the front lines, a special type of gas mask was developed that dogs were trained to wear. other gas masks were developed during world war i and the time following for horses in the various mounted units that operated near the front lines. in america, thousands of gas masks were produced for american as well as allied troops. mine safety appliances was a chief producer. this mask was later used widely in industry. second world war a british couple wearing gas masks in their home in 1941 the british respirator, anti-gas (light) was developed in 1943 by the british. it was made of plastic and rubber-like material that greatly reduced the weight and bulk compared to world war i gas masks, and fitted the user's face more snugly and comfortably. the main improvement was replacing the separate filter canister connected with a hose by an easily replaceable filter canister screwed on the side of the gas mask. also, it had replaceable plastic lenses. modern mask gas mask development since has mirrored the development of chemical agents in warfare, filling the need to protect against ever more deadly threats, biological weapons, and radioactive dust in the nuclear era. however, for agents that cause harm through contact or penetration of the skin, such as blister agent or nerve agent, a gas mask alone is not sufficient protection, and full protective clothing must be worn in addition to protect from contact with the atmosphere. for reasons of civil defence and personal protection, individuals often buy gas masks since they believe that they protect against the harmful effects of an attack with nuclear, biological, or chemical (nbc) agents, which is only partially true, as gas masks protect only against respiratory absorption. most military gas masks are designed to be capable of protecting against all nbc agents, but they can have filter canisters proof against those agents (heavier) or only against riot control agents and smoke (lighter and often used for training purposes). there are lightweight masks solely for protection against riot-control agents and not for nbc situations. although thorough training and the availability of gas masks and other protective equipment can nullify the casualty-causing effects of an attack by chemical agents, troops who are forced to operate in full protective gear are less efficient in completing tasks, tire easily, and may be affected psychologically by the threat of attack by those weapons. during the cold war, it was seen as inevitable that there would be a constant nbc threat on the battlefield and so troops needed protection in which they could remain fully functional; thus, protective gear and especially gas masks have evolved to incorporate innovations in terms of increasing user comfort and compatibility with other equipment (from drinking devices to artificial respiration tubes, to communications systems etc.). iranian soldier wearing a us m17 protective mask on the frontline of the iran–iraq war during the iran–iraq war (1980–88), iraq developed its chemical weapons program with the help of european countries such as germany and france and used them in a large scale against iranians and iraqi kurds. iran was unprepared for chemical warfare. in 1984, iran received gas masks from the republic of korea and east germany, but the korean masks were not suited for the faces of non-east asian people, the filter lasted for only 15 minutes, and the 5,000 masks bought from east germany proved to be not gas masks but spray-painting goggles. as late as 1986, iranian diplomats still travelled in europe to buy active charcoal and models of filters to produce defensive gear domestically. in april 1988, iran started domestic production of gas masks by the iran yasa factories. in schools pioneers in gas masks. ussr, 1937 many civilians learned how to use gas masks through the civil defense department, but children received most gas mask education in school drills. schools would implement gas mask education and training after the outbreak of a war. schools would harshly enforce the compulsory carrying of gas masks at all times. gas mask and air raid drills were closely related and children would be made to wear gas masks in everyday activities, including gymnastics. the wearing of gas masks in the classrooms were especially difficult for teachers as they had trouble distinguishing one child from another. the gas masks became as uniform as the students' uniforms. other civilians learned the use of a gas mask through posters, pamphlets, and radio lectures, but children learned through cartoons and rhymes such as "coughs and sneezes spread diseases".