How Long Does A Gas Mask Filter Last

Protection from inhaling airborne pollutants and toxic gases

A World War I British P Helmet c. 1915

Indian muleteers and mule wearing gas masks, France, February 21, 1940

A Shine MUA gas mask, used in the 1970s and 1980s

A gas mask is a mask used to protect the wearer from inhaling airborne pollutants and toxic gases. The mask forms a sealed comprehend over the nose and oral cavity, simply may also cover the eyes and other vulnerable soft tissues of the face. Most gas masks are also respirators, though the word gas mask is often used to refer to military equipment (such every bit a field protective mask), the scope used in this commodity. The gas mask only protects the user from digesting, inhaling, and contact through the eyes (many agents impact through middle contact). Most combined gas mask filters will last around 8 hours in a biological or chemical situation. Filters against specific chemical agents can terminal upward to xx hours.

Airborne toxic materials may be gaseous (for instance, chlorine or mustard gas), or particulates (such equally biological agents). Many filters provide protection from both types.

The kickoff gas masks mostly used round lenses made of glass, mica or cellulose acetate to allow vision. Glass and mica were quite brittle and needed frequent replacement. The later Triplex lens style (a cellulose acetate lens sandwiched between glass ones)^[1] became more than popular, and alongside plain cellulose acetate they became the standard into the 1930s. Panoramic lenses were not pop until the 1930s, simply there are some examples of those existence used even during the war (Austro-Hungarian 15M). Later, stronger polycarbonate came into use.

Some masks have one or two compact air filter containers screwed onto inlets, while others have a large air filtration container connected to the gas mask via a hose that is sometimes confused with an air-supplied respirator in which an alternate supply of fresh air (oxygen tanks) is delivered.

Principles of structure [edit]

Assimilation is the process of beingness fatigued into a (usually larger) body or substrate, and adsorption is the process of degradation upon a surface. This tin can be used to remove both particulate and gaseous hazards. Although some grade of reaction may have place, it is not necessary; the method may piece of work by attractive charges. For example, if the target particles are positively charged, a negatively charged substrate may be used. Examples of substrates include activated carbon, and zeolites. This effect tin be very elementary and highly constructive, for example using a damp cloth to comprehend the mouth and nose while escaping a fire. While this method can be effective at trapping particulates produced by combustion, it does not filter out harmful gases which may be toxic or which readapt the oxygen required for survival.

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  US Navy MCU-two/P gas mask arrangement.

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  Gas mask used by the French military. The filter cartridge is connected via a flexible hose.

Rubber of old gas masks [edit]

Gas masks have a useful lifespan limited by the absorbent chapters of the filter. Filters finish to provide protection when saturated with hazardous chemicals, and degrade over fourth dimension even if sealed. Most gas masks take sealing caps over the air intake and are stored in vacuum-sealed numberless to foreclose the filter from degrading due to exposure to humidity and pollutants in normal air. Unused gas mask filters from World War 2 may not protect the wearer at all, and could exist harmful if worn due to long-term changes in the chemic composition of the filter.^{[ citation needed ]}

An asbestos-containing Russian GP-5 filter and a safety modern one in comparison.

Some World War Two or Soviet Cold War gas masks independent chrysotile asbestos or crocidolite asbestos in their filters,^{[2] [three] [4]} not known to be harmful at the time. It is non reliably known for how long the materials were used in filters. Breathing blue asbestos in the factories resulted in the death of 10 pct of the workforce due to pleural and peritoneal mesothelioma, between 2.v and 3.2 times the normal incidence of lung or respiratory cancers.^[5]

Many stories have circulated about various Russian gas masks mutual in surplus stores and their filters; the GP-5 is often idea to have an asbestos filter. In normal employ the asbestos is independent inside the filter, just could be breathed in if the filter is damaged.^{[ citation needed ]} Modern gas masks do non use asbestos.

Typically, masks using 40 mm connections are a more than recent design. Rubber degrades with time, and so boxed unused "modern type" masks can exist cracked and leak. The US C2 canister (black) contains hexavalent chromium; studies past the U.S. Army Chemical Corps found that the level in the filter was acceptable, merely suggest caution when using, as information technology is a carcinogen.^[six]

Modern filter classification [edit]

The filter is selected according to the toxic compound.^[seven] Each filter type protects against a particular adventure and is color-coded:

Filter types

European union Class, colour	U.s. color[8]	Take chances
AX, brown	black	Depression-boiling (≤65 °C) organic compounds
A, chocolate-brown		High-boiling (>65 °C) organic compounds
B, grey	(many)	Inorganic gases (hydrogen sulfide, chlorine, hydrogen cyanide)
E, yellow	white	Acidic gases (Sulfur dioxide and hydrogen chloride)
K, green	greenish	Ammonia and amines
CO, black	blue	Carbon monoxide
Hg, scarlet	N/A	Mercury vapor
Reactor, orangish	magenta	Radioactive (iodine and methyl iodide)
P, white	purple, orange, or teal	particles

Particle filters are often included, because in many cases the hazardous materials are in the form of mist, which tin can be captured by the particle filter before entering the chemical adsorber. In Europe and jurisdictions with similar rules such as Russia and Australia, filter types are given suffix numbers to point their capacity. For not-particle hazards, the level "1" is assumed and a number "2" is used to bespeak a better level. For particles (P), three levels are e'er given with the number.^[7] In the US, only the particle part is further classified by NIOSH air filtration ratings.^[viii]

A filter type that can protect against multiple hazards is notated with the European symbols concatenated with each other. Examples include ABEK, ABEK-P3, and ABEK-HgP3.^[vii] A2B2E2K2-P3 is the highest rating of filter bachelor.^{[ when? ]} An entirely dissimilar "multi/CBRN" filter class with an olive color is used in the Us.^[8]

Filtration may exist aided with an air pump to improve wearer comfort. Filtration of air is only possible if at that place is sufficient oxygen in the first place. Thus, when handling asphyxiants, or when ventilation is poor or the hazards are unknown, filtration is not possible and air must be supplied (with a SCBA system) from a pressurized bottle as in scuba diving.

Use [edit]

A 1939 Second World War-era baby'southward gas mask in Monmouth Regimental Museum. This blueprint covered the whole of the baby except for its legs.

A worker in a found nursery wears a respirator to protect against the insecticides sprayed in the greenhouses, 1930.

A modern mask typically is constructed of an elastic polymer in various sizes. It is fitted with various adjustable straps which may exist tightened to secure a good fit. Crucially, it is continued to a filter cartridge most the mouth either directly, or via a flexible hose. Some models contain drinking tubes which may be connected to a water canteen. Corrective lens inserts are also available for users who crave them.

Masks are typically tested for fit before use. After a mask is fitted, it is frequently tested past diverse challenge agents. Isoamyl acetate, a synthetic banana flavourant, and camphor are ofttimes used as innocuous claiming agents. In the military, teargases such as CN, CS, and stannic chloride in a chamber may exist used to give the users confidence in the efficacy of the mask.^[nine]

Shortcomings [edit]

The protection of a gas mask comes with some disadvantages. The wearer of a typical gas mask must exert extra endeavor to breathe, and some of the exhaled air is re-inhaled due to the dead space betwixt the facepiece and the user's confront. The exposure to carbon dioxide may exceed its OELs (0.5% past volume/nine grammes per cubic metre for an eight-hour shift; i.4%/27 grammes per m³ for 15 minutes' exposure)^[10] by a cistron of many times: for gas masks and elastomeric respirators, up to 2.6%^[eleven]);^[12] and in case of long-term utilize, headache,^[13] dermatitis and acne^[fourteen] may announced. The UK HSE textbook recommends limiting the use of respirators without air supply (that is, not PAPR) to one hr.^[15]

Reaction and exchange [edit]

This principle relies on substances harmful to humans existence unremarkably more reactive than air. This method of separation volition use some form of more often than not reactive substance (for example an acid) coating or supported by some solid material. An example is synthetic resins. These tin can be created with different groups of atoms (ordinarily called functional groups) that have unlike properties. Thus a resin tin can be tailored to a particular toxic group. When the reactive substance comes in contact with the resin, it will bail to it, removing it from the air stream. It may as well exchange with a less harmful substance at this site.

Though it was crude, the hypo helmet was a stopgap measure for British troops in the trenches that offered at least some protection during a gas assail. Equally the months passed and toxicant gas was used more often, more sophisticated gas masks were developed and introduced. In that location are two main difficulties with gas mask design:

• The user may be exposed to many types of toxic material. Armed forces personnel are especially decumbent to beingness exposed to a diverse range of toxic gases. Notwithstanding, if the mask is for a particular utilize (such as the protection from a specific toxic cloth in a manufactory), then the design can be much simpler and the cost lower.
• The protection will wear off over time. Filters will clog up, substrates for assimilation will fill up, and reactive filters will run out of reactive substances. Thus the user only has protection for a limited fourth dimension, and then they must either replace the filter device in the mask, or use a new mask.

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  A primitive respirator was designed by Alexander von Humboldt in 1799 for undercover mining

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  Finnish civilian gas mask from 1939. These masks were distributed during World War 2

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  Mother and baby with gas masks, 1941

History and development [edit]

Early breathing devices [edit]

According to Popular Mechanics, "The common sponge was used in aboriginal Greece every bit a gas mask..."^[16] In 1785, Jean-François Pilâtre de Rozier invented a respirator.

Primitive respirator examples were used past miners and introduced by Alexander von Humboldt in 1799, when he worked as a mining engineer in Prussia.^[17] The forerunner to the modern gas mask was invented in 1847 by Lewis P. Haslett, a device that independent elements that allowed breathing through a nose and mouthpiece, inhalation of air through a seedling-shaped filter, and a vent to exhale air dorsum into the atmosphere.^[18] Beginning Facts states that a "gas mask resembling the modernistic type" was patented by Lewis Phectic Haslett of Louisville, Kentucky, who received a patent on June 12, 1849.^[19] U.S. patent #six,529^[20] issued to Haslett, described the starting time "Inhaler or Lung Protector" that filtered grit from the air.

Early on versions were constructed by the Scottish pharmacist John Stenhouse in 1854^[21] and the physicist John Tyndall in the 1870s.^[22] Some other early pattern was the "Prophylactic Hood and Fume Protector" invented past Garrett Morgan in 1912, and patented in 1914. It was a uncomplicated device consisting of a cotton hood with two hoses which hung downwardly to the floor, allowing the wearer to breathe the safer air plant at that place. In addition, moist sponges were inserted at the end of the hoses in guild to better filter the air. This was later modified to include its own air supply, leading to World War I era gas masks.^{[23] [24] [25] [26]}

Offset World State of war [edit]

High german soldiers with gas masks, 1916

The Beginning Earth War brought about the first demand for mass-produced gas masks on both sides because of all-encompassing use of chemical weapons. The High german army successfully used poison gas for the first time against Centrolineal troops at the 2d Boxing of Ypres, Belgium on Apr 22, 1915.^[27] An immediate response was cotton wool wrapped in muslin, issued to the troops by May ane. This was followed by the Black Veil Respirator, invented by John Scott Haldane, which was a cotton pad soaked in an absorptive solution which was secured over the oral fissure using black cotton veiling.^[28]

Seeking to meliorate on the Black Veil respirator, Cluny MacPherson created a mask fabricated of chemical-absorbing fabric which fitted over the entire head.^[29] A 50.5 cm × 48 cm (19.nine in × 18.nine in) canvas hood treated with chlorine-absorbing chemicals, and fitted with a transparent mica eyepiece.^[xxx] Macpherson presented his idea to the British War Function Anti-Gas Department on May 10, 1915; prototypes were adult shortly afterwards.^[31] The pattern was adopted past the British Army and introduced every bit the British Fume Hood in June 1915; Macpherson was appointed to the State of war Role Committee for Protection confronting Poisonous Gases.^[32] More elaborate sorbent compounds were added later to further iterations of his helmet (PH helmet), to defeat other respiratory poisonous substance gases used such as phosgene, diphosgene and chloropicrin. In summer and autumn 1915, Edward Harrison, Bertram Lambert and John Sadd adult the Big Box Respirator.^[33] This canister gas mask had a tin can containing the absorbent materials by a hose and began to exist issued in February 1916. A compact version, the Small Box Respirator, was fabricated a universal upshot from August 1916.

In the kickoff gas masks of Earth State of 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 basics such every bit coconuts, chestnuts, equus caballus-chestnuts, and peach stones performed much better than woods charcoal. These waste materials were collected from the public in recycling programs to help the war effort.^[34]

The first effective filtering activated charcoal gas mask in the world was invented in 1915 by Russian chemist Nikolay Zelinsky.^[35]

Also in Earth War I, since dogs were frequently used on the front end lines, a special blazon of gas mask was developed that dogs were trained to habiliment.^[36] Other gas masks were developed during World State of war I and the time following for horses in the various mounted units that operated near the front lines.^[37] In America, thousands of gas masks were produced for American as well equally Allied troops. Mine Prophylactic Appliances was a chief producer. This mask was afterwards used widely in industry.^[38]

Second World State of war [edit]

A British couple wearing gas masks in their home in 1941

The British Respirator, Anti-Gas (Calorie-free) was developed in 1943 past the British.^[39] Information technology was made of plastic and prophylactic-like material that profoundly reduced the weight and bulk compared to World State of 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. Too, information technology had replaceable plastic lenses.

Modern mask [edit]

Gas mask development since has mirrored the development of chemic agents in warfare, filling the need to protect against ever more deadly threats, biological weapons, and radioactive dust in the nuclear era. All the same, for agents that cause damage through contact or penetration of the skin, such as blister agent or nerve agent, a gas mask alone is not sufficient protection, and total protective habiliment must be worn in addition to protect from contact with the temper. For reasons of civil defence and personal protection, individuals often buy gas masks since they believe that they protect against the harmful furnishings of an attack with nuclear, biological, or chemical (NBC) agents, which is merely partially truthful, as gas masks protect but against respiratory absorption. Nigh war machine gas masks are designed to be capable of protecting confronting all NBC agents, but they tin have filter canisters proof against those agents (heavier) or merely confronting riot command agents and fume (lighter and oft used for training purposes). There are lightweight masks solely for protection against riot-control agents and not for NBC situations.^{[ citation needed ]}

Although thorough training and the availability of gas masks and other protective equipment can nullify the casualty-causing effects of an attack past chemic agents, troops who are forced to operate in total protective gear are less efficient in completing tasks, tire easily, and may exist affected psychologically by the threat of attack by those weapons. During the Cold War, information technology was seen as inevitable that there would exist a constant NBC threat on the battlefield and and then troops needed protection in which they could remain fully functional; thus, protective gear and especially gas masks take evolved to contain innovations in terms of increasing user condolement and compatibility with other equipment (from drinking devices to artificial respiration tubes, to communications systems etc.).

Iranian soldier wearing a U.s.a. M17 protective mask on the frontline of the Iran–Iraq War

During the Iran–Iraq War (1980–88), Iraq adult its chemical weapons program with the help of European countries such as Federal republic of germany and France^[xl] and used them in a large scale confronting Iranians and Iraqi Kurds. Islamic republic of iran was unprepared for chemical warfare. In 1984, Iran received gas masks from the Republic of korea and East Federal republic of germany, but the Korean masks were not suited for the faces of not-East Asian people, the filter lasted for only 15 minutes, and the five,000 masks bought from Eastward Federal republic of germany proved to exist not gas masks only spray-painting goggles. As late every bit 1986, Iranian diplomats withal 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.^[41]

In schools [edit]

Many civilians learned how to use gas masks through the ceremonious defense department, just children received nearly gas mask education in school drills. Schools would implement gas mask teaching and training afterward 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 equally they had trouble distinguishing i kid from another. The gas masks became as uniform as the students' uniforms. Other civilians learned the utilize of a gas mask through posters, pamphlets, and radio lectures, but children learned through cartoons and rhymes such as "coughs and sneezes spread diseases".^{[ commendation needed ]}

See likewise [edit]

• Assigned Protection Factors
• Cartridges and canisters of air-purifying respirators
• GP-five gas mask
• Hopcalite
• M2 Gas Mask
• M40 Field Protective Mask
• M50 articulation service general purpose mask
• C-four Protective Mask
• NBC suit
• PH helmet
• Plague doctor's outfit
• Respirator
• Respirator fit test
• Respirators testing in the workplaces
• Respirator assigned protection factors
• Smoke hood

Notes [edit]

1. ^ Rumpf, Hans. Gasschutz.
2. ^ "Porton Downwardly report on the presence of asbestos in Earth War II respirator canisters" (PDF). p. 2 (summary).
3. ^ Burns, Judith (May 13, 2014). "Ban wartime gas masks, schools told". BBC News . Retrieved Baronial 21, 2018.
4. ^ Dail, David H.; Hammar, Samuel P.; Colby, Thomas V. (December six, 2012). Pulmonary Pathology — Tumors. Springer Science & Business Media. ISBN978-1-4612-2496-ix.
5. ^ Acheson, E D; Gardner, 1000 J; Pippard, E C; Crud, 50 P (1982). "Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up". Occupational and Environmental Medicine. 39 (four): 344–8. doi:10.1136/oem.39.4.344. PMC1009064. PMID 6291580.
6. ^ "Wayback Automobile" (PDF). Archived from the original (PDF) on 2016-04-29. Retrieved 2022-02-05 .
7. ^ ^{a b c} "Guide for selection and utilize of filtering devices" (PDF). draeger.com. Archived from the original (PDF) on May 26, 2012. Retrieved February 22, 2013.
8. ^ ^{a b c} "OSHA Message: General Respiratory Protection Guidance for Employers and Workers". Occupational Safety and Health Administration.
9. ^ "Archived copy" (PDF). Archived from the original (PDF) on Oct xx, 2012. Retrieved July nine, 2010. {{cite web}}: CS1 maint: archived re-create as championship (link)
10. ^ Popova, Anna, ed. (2018). "Substance #2138 Carbon dioxide". Aseptic standard 2.2.5.3532-18.Occupational exposure limits for toxic substances in workplace air [ГН 2.2.5.3532-xviii Предельно допустимые концентрации (ПДК) вредных веществ в воздухе рабочей зоны] (in Russian). Moscow: Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. p. 170.
11. ^ Mean values for several models; some models may provide a stronger exposure to carbon dioxide.
12. ^ Sinkule E., Turner Due north., Hota Due south. (2003). "Automatic breathing and metabolic simulator (ABMS) CO₂ test for powered and non-powered air-purifying respirators, airline respirators, and gas mask". American Industrial Hygiene Conference and Exposition, May ten-15, 2003. Dallas, Texas: American Industrial Hygiene Association. p. 54. {{cite volume}}: CS1 maint: multiple names: authors list (link) copy
13. ^ E.C.H. Lim, R.C.S. Seet, K.‐H. Lee, E.P.V. Wilder‐Smith, B.Y.Due south. Chuah, B.K.C. Ong (2006). "Headaches and the N95 face-mask amongst healthcare providers". Acta Neurologica Scandinavica. John Wiley & Sons. 113 (3): 199–202. doi:10.1111/j.1600-0404.2005.00560.ten. ISSN 0001-6314. PMC7159726. PMID 16441251. {{cite journal}}: CS1 maint: multiple names: authors list (link)
14. ^ Chris C.I. Foo, Anthony T.J. Goon, Yung-Hian Leow, Chee-Leok Goh (2006). "Adverse skin reactions to personal protective equipment against severe astute respiratory syndrome – a descriptive study in Singapore". Contact Dermatitis. John Wiley & Sons. 55 (5): 291–294. doi:10.1111/j.1600-0536.2006.00953.x. ISSN 0105-1873. PMC7162267. PMID 17026695. {{cite journal}}: CS1 maint: multiple names: authors list (link)
15. ^ The Health and Safety Executive (2013). Respiratory protective equipment at piece of work. A applied guide. HSG53 (4 ed.). Crown. p. 59. ISBN978-0-71766-454-2 . Retrieved June ten, 2018.
16. ^ "Popular Mechanics". January 1984. p. 163
17. ^ Von Humboldt, Alexander (1799). Ueber dice unterirdischen Gasarten und die Mittel, ihren Nachtheil zu vermindern: Ein Beytrag zur Physik der praktischen Bergbaukunde. Braunschweig, Friedrich Vieweg.
18. ^ "The invention of the gas mask". Ian Taggart. Archived from the original on May two, 2013.
19. ^ Drobnicki, John A.; Asaro, Richard (2001). "Historical Fabrications on the Internet". In Su, Di (ed.). Evolution in Reference and Data Services: The Bear upon of the Cyberspace. Binghamton, New York: Haworth Information Press. p. 144. ISBN978-0-7890-1723-9.
20. ^ Us 6529A, Haslett, Lewis P., "Lung Protector", issued 1849-06-12
21. ^ Alvin Yard. Benson (2010). Inventors and inventions. Salem Printing. ISBN978-1-58765-526-5.
22. ^ The Environment and Its Effect Upon Human being: Symposium Held at Harvard School of Public Health, August 24-August 29, 1936, as Part of Harvard University Tercentenary Celebration, 1636-1936. Harvard School of Public Health. 1937.
23. ^ Jr, Henry Louis Gates; Higginbotham, Evelyn Brooks (Apr 29, 2004). African American Lives. Oxford Academy Press. ISBN9780199882861. By World War I, Morgan had modified the mask to acquit its own air supply, creating the first gas mask, which by 1917 was standard equipment for the U.Due south. Army.
24. ^ "Garrett Augustus Morgan". PBS Who Made America?. He sold the hoods to the U.S. Navy, and the Army used them in Earth State of war I.
25. ^ "Morgan, Garrett 1877–1963". Encyclopedia.com Gimmicky Blackness Biography. Morgan would later perfect his "breathing device" into a gas mask that was used extensively in Globe War I.
26. ^ "Garrett Morgan Biography". Biography.com People. Morgan's animate device became the prototype and precursor for the gas masks used during World War I, protecting soldiers from toxic gas used in warfare.
27. ^ "Second Battle of Ypres Begins". history.com . Retrieved April 22, 2018.
28. ^ Wetherell & Mathers 2007, p. 157.
29. ^ Victor Lefebure (1923). The Riddle of the Rhine: Chemical Strategy in Peace and War . The Chemical Foundation Inc. ISBN0-585-23269-5.
30. ^ "Macpherson Gas Hood . Accession #980.222". The Rooms Provincial Museum Athenaeum (St. John'due south, NL). Retrieved August 5, 2017.
31. ^ Mayer-Maguire & Baker 2015.
32. ^ "Biographical entry Macpherson, Cluny (1879 - 1966)". livesonline.rcseng.air conditioning.uk . Retrieved April 22, 2018.
33. ^ "The UK". The Gas Mask Database.
34. ^ In one case Worthless Things that take Of a sudden Become of Value, Popular Science monthly, Dec 1918, page eighty, scanned by Google Books
35. ^ Kozhevnikov, A B (2004). Stalin's keen science: the times and adventures of Soviet physicists (illustrated, reprint ed.). Purple College Printing. pp. 10–11. ISBN978-1-86094-419-2 . Retrieved April 28, 2009.
36. ^ "Gas-Masks for Dogs / Dumb Heroes of the Fighting Front", Popular Scientific discipline monthly, December 1918, folio 75, Scanned by Google Books
37. ^ "Gas Masks to Baby-sit Horses and Dogs in State of war" Popular Mechanics, July 1934, bottom pg. 75
38. ^ Pittsburgh Post-Gazette, November xxx, 1960
39. ^ "Respirator, Anti-Gas (Light) MKII: With Haversack Carrier & contents".
40. ^ "Iraqi Scientist Reports on German, Other Help for Iraq Chemic Weapons Program". fas.org . Retrieved 2021-06-28 .
41. ^ Zanders, Jean Pascal (March 7, 2001). "Iranian Utilize of Chemic Weapons: A Critical Assay of Past Allegations". CNS Briefings. James Martin Center for Nonproliferation Studies. Archived from the original on March twenty, 2015. Retrieved March 27, 2016.

Bibliography [edit]

• Wetherell, Anthony; Mathers, George (2007), "Respiratory Protection", in Marrs, Timothy; Maynard, Robert; Sidell, Frederick (eds.), Chemic Warfare Agents: Toxicology and Handling, New York: Wiley, pp. 157–174, ISBN978-0470013595
• Mayer-Maguire, Thomas; Baker, Brian (2015), British Military Respirators and Anti-Gas Equipment of the Two World Wars, Crowood

External links [edit]

Wikimedia Commons has media related to Gas mask.

• How Stuff Works - Gas Masks Scientific discipline.com
• The History of Gas Masks inventors.nearly.com, Nigh, Inc. updated August half dozen, 2016
• Respirator Fact Sheet
• CBRN SCBA NIOSH Canonical Respirators List of NIOSH Approved CBRN SCBA respirators

How Long Does A Gas Mask Filter Last,

Source: https://en.wikipedia.org/wiki/Gas_mask#:~:text=Most%20combined%20gas%20mask%20filters,(such%20as%20biological%20agents).

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