Gas mask

A gas mask ismask worn onfaceprotectbody from airborne pollutantstoxins. The mask may covereyesother vulnerable soft tissues offace,will always formsealed cover overnosemouth.

Toxins may be gaseous (for examplechlorine usedWWI), or particulate (such as many biological agents developedweapons). Many gas masks include protection from both typestoxin. The advantage ofgas mask over other breathing devicesthatdoes not requireusercarry an air supply (as inusescuba gear). However, this means thatuserdependent onair inatmosphere,very mediumwhich toxins may be present. Thus,mask must removetoxins,relay cleaned air touser.

Therethree main waysachieving this:

Tablecontents

1 Filtration 2 Absorptionadsorption 3 Reactionexchange 4 HistoryDevelopement ofGas Mask

Filtration

This obviously lends itselfparticulate toxins. A filter works by having holes thatsmaller thanparticlesbe removed. As many pollutant moleculesparticlesmuch bigger than air molecules (mostly O₂N₂) this worksmany applications. However,smallergap through whichair haspass,greaterpressure that must be exerteddrawair through. Asuser's lungs provide this pressure there islimit ashow small these passages may be. Thusextract many gaseous toxins, other methods must be used.

Absorptionadsorption

Absorption isprocessbeing drawn into(usually larger) body, or substrate,adsorption isprocessdeposition uponsurface. This can be usedremove both particulategaseous toxins. Although some formreaction may take place, itnot necessary,principle may work by attractive charges (for example iftarget toxinpositively charged, usenegatively charged substrate). Examplessubstrates include activated carbon,zeolites. this effect can be very simplehighly effective,example usingdamp clothcovermouthnose whilst escapingfire. Most ofharmful vapourssmoke will be dissolved inwater oncloth, giving you vital extra secondsescape.

Reactionexchange

This principle relies uponfact that substances that can do harmhumansusually more reactive than air. This methodseparation will use some formgenerally reactive substance (for example an acid) coating or supported by some solid material. An excellent exampleresins. These can be createddifferent groupsatoms (usually called functional groups) that exhibit different properties. Thusresin can be tailored toparticular grouptoxins. Whentoxin comes into contact withreactive substance,will bondit, removingfromair stream. It may also exchange withmore harmless substance at this site.

Theretwo main difficultiesgas-mask design:

The user may be exposedmany different typestoxins. Thisespecially true ofmasks thatmilitary use,may literally have anything thrown at them. However ifmaskforparticular use (such asremoval ofspecific typetoxin infactory), thendesign can be much simpler andcost lower.

The protection will wear off over time. Filters will clog-up, substratesabsorption will fill-up,reactive filters will run outreactive substance. This means thatuser only has protectionso long,thenmust either replacefilter device inmask, or usenew mask.

HistoryDevelopement ofGas Mask

The gas mask began as"Safety HoodSmoke Protector" invented by African-American inventor, Garrett A. Morgan1912,patented1914. Despite relentless racial discrimination, Morgan won acclaimhis device when1916 he, his brother,two volunteers used his devicerescue numerous men fromgassmoke-filled tunnels beneath Lake Erie, inCleveland Waterworks.

Morgan receivedCarnegie Medal andMedalBravery fromcityCleveland. The International AssociationFire Engineers made Garrett A. Morgan an honorary member. Some ordersMorgan's mask were cancelled oncewas discovered thatdevices were inventedmanufactured byBlack man. Nevertheless, fire fighters camerely upon Morgan's Safety Hood, andinvention eventually helped save thousands upon thousands from chlorine gas during World War I.