Gas mask - gas mask

A mask worn on the face to protect the respiratory system from air contaminated by toxic gases and smoke. It is also called a gas mask or gas mask. It consists of a face mask, usually made of rubber, that fits tightly against the face, and an absorption canister that absorbs and decomposes toxic substances. There are two types: a direct-connect type in which the face mask and the absorption canister are integrated, and an isolated type in which the two are connected by a rubber tube. Poisonous gases with high boiling points, such as yperite and lewisite, can be removed by activated carbon adsorption, but gases with low boiling points, such as phosgene and hydrogen cyanide, are removed by chemical decomposition by packing activated carbon with decomposing agents such as copper salts, zinc salts, and silver salts adsorbed in the absorption canister. Aerosols and fine powders are removed by a cotton or paper filter. Disaster prevention gas masks are classified according to their use, and the absorption canisters are assigned symbols and colors according to the toxic substances to be removed. Except in cases such as oxygen inhalation, a face mask that covers the entire face except the eyes is usually used.

[Iwamoto Shinbu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

有毒ガス、煙などで汚染された空気から呼吸器を防護するために、顔面に装着するマスク。防毒面、防毒マスクともよばれる。顔面に密着する主としてゴム製の面と、有毒成分を吸着、分解する吸収缶からなるが、面と吸収缶が一体となっている直結式と、両者をゴム管で連結する隔離式とがある。イペリット、ルイサイトのような沸点の高い毒ガスは活性炭吸着によって除去できるが、ホスゲン、シアン化水素のような低沸点のガスは、活性炭に銅塩、亜鉛塩、銀塩などの分解剤を吸着させたものを吸収缶に詰め、化学的分解によって除く。エーロゾルや微粒粉は、綿あるいは紙製の濾過(ろか)器によって除く。防災用防毒マスクは用途に応じて分類されており、吸収缶には除去される有毒物に応じた記号と色が定められている。酸素吸入のような場合を除き、目のほか顔面全体を覆う面を用いるのが普通である。

［岩本振武］

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