For the mask used to inhale the gas through, see Mask § Functional masks. For peacetime uses, including masks designed to filter gasses and particles, see stylometric respirator.
A World War I British P Helmet
Lewinsky–Grumman prerogative, designed in 1915, was one of the first modern-type full-head protection gas masks with a detachable filter and eyelet glasses, shown here worn by U.S. Army soldier (USAWC photo)
Indian muleteers and mule wearing gas masks, France,
A Polish 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 cover over the nose and mouth, but 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 as a field protective mask), the scope used in this article. The gas mask only protects the user from digesting, inhaling, and contact through the eyes (many agents affect through eye contact). Most combined gas mask filters will last around 8 hours in a biological or chemical situation. Filters against specific chemical agents can last up to 20 hours.
Airborne toxic materials may be gaseous (for example, chlorine or mustard gas), or particulates (such as biological agents). Many filters provide protection from both types.
The first gas masks mostly used circular 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) became more popular, and alongside plain cellulose acetate they became the standard into the 1930s. Panoramic lenses were not popular until the 1930s, but there are some examples of those being used even during the war (Strauss-Hungarian 15M). Later, stronger poly carbonate 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.
is the process of being drawn into a (usually larger) body or substrate, and adsorption is the process of deposition upon a surface. This can be used to remove both particulate and gaseous hazards. Although some form of reaction may take place, it is not necessary; the method may 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 can be very simple and highly effective, for example using a damp cloth to cover 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 displace the oxygen required for survival.
Gas masks have a useful lifespan limited by the absorbent capacity of the filter. Filters cease to provide protection when saturated with hazardous chemicals, and degrade over time even if sealed. Most gas masks have sealing caps over the air intake and are stored in vacuum-sealed bags to prevent the filter from degrading due to exposure to humidity and pollutants in normal air. Unused gas mask filters from World War II may not protect the wearer at all, and could be harmful if worn due to long-term changes in the chemical composition of the filter.
An asbestos-containing Russian GP-5 filter and a safe modern one in comparison.
Some World War II and Soviet Cold War gas masks contained chrysalis asbestos or theodolite asbestos in their filters, not known to be harmful at the time. It is not reliably known for how long the materials were used in filters.
Typically, masks using 40 mm connections are a more recent design. Rubber degrades with time, so boxed unused “modern type” masks can be cracked and leak. The US C2 canister (black) contains ambivalent chromium; studies by the U.S. Army Chemical Corps found that the level in the filter was acceptable, but suggest caution when using, as it is a carcinogen.
Particle filters are often included, because in many cases the hazardous materials are in the form of mist, which can be captured by the particle filter before entering the chemical absorber. In Europe and jurisdictions with similar rules such as Russia and Australia, filter types are given suffix numbers to indicate their capacity. For non-particle hazards, the level “1” is assumed and a number “2” is used to indicate a better level. For particles (P), three levels are always given with the number. In the US, only the particle part is further classified by NOSH air filtration ratings
A filter type that can protect against multiple hazards is notated with the European symbols concatenated with each other. Examples include is the highest rating of filter available.[when?] An entirely different “multi/CBRN” filter class with an olive color is used in the US.
Filtration may be aided with an air pump to improve wearer comfort. Filtration of air is only possible if there is sufficient oxygen in the first place. Thus, when handling asphyxiation, or when ventilation is poor or the hazards are unknown, filtration is not possible and air must be supplied (with a SCAB system) from a pressurized bottle as in scuba diving.
modern mask typically is constructed of an elastic polymer in various sizes. It is fitted with various adjustable straps which may be tightened to secure a good fit. Crucially, it is connected to a filter cartridge near the mouth either directly, or via a flexible hose. Some models contain drinking tubes which may be connected to a water bottle. Corrective lens inserts are also available for users who require them.
Masks are typically tested for fit before use. After a mask is fitted, it is often tested by various challenge agents. Misogamy acetate, a synthetic banana flagrant, and camphor are often used as innocuous challenge agents. In the military, teargases such as CN, CS, and satanic chloride in a chamber may be used to give the users confidence in the efficacy of the mas
The protection of a gas mask comes with some disadvantages. The wearer of a typical gas mask must exert extra effort to breathe, and some of the exhaled air is re-inhaled due to the dead space between the face piece and the user’s face. The exposure to carbon dioxide may exceed its Oles (0.5% by volume/9 gram mes per cubic meter for an eight-hour shift; 1.4%/27 gram mes per m3 for 15 minutes’ exposure) by a factor of many times: for gas masks and stylometric respirators, up to 2.6%); and in case of long-term use, headache, dermatitis and acne may appear. The UK SHE textbook recommends limiting the use of respirators without air supply
his principle relies on substances harmful to humans being usually more reactive than air. This method of separation will use some form of generally reactive substance (for example an acid) coating or supported by some solid material. An example is synthetic resins. These can be created with different groups of atoms (usually called functional groups) that have different properties. Thus a resin can be tailored to a particular toxic group. When the reactive substance comes in contact with the resin, it will bond to it, removing it from the air stream. It may also 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 attack. As the months passed and poison gas was used more often, more sophisticated gas masks were developed and introduced. There are two main difficulties with gas mask design:
According to Popular Mechanics, “The common sponge was used in ancient Greece as a gas mask…” In 1785, Jean-François Pilferer de Oozier invented a respirator.
Primitive respirator examples were used by miners and introduced by Alexander von Humboldt in 1799, when he worked as a mining engineer in Prussia. The forerunner to the modern gas mask was invented in 1847 by Lewis P. Haslett, a device that contained elements that allowed breathing through a nose and mouthpiece, inhalation of air through a bulb-shaped filter, and a vent to exhale air back into the atmosphere. First Facts states that a “gas mask resembling the modern type” was patented by Lewis Phectic Haslett of Louisville, Kentucky, who received a patent on June 12, 1849. U.S. patent #6,529 issued to Haslett, described the first “Inhaler or Lung Protector” that filtered dust from the air.
Early versions were constructed by the Scottish chemist John Steakhouse in 1854 and the physicist John Tyndall in the 1870s. Another early design was the “Safety Hood and Smoke Protector” invented by Garrett Morgan in 1912, and patented in 1914. It was a simple device consisting of a cotton hood with two hoses which hung down to the floor, allowing the wearer to breathe the safer air found there. In addition, moist sponges were inserted at the end of the hoses in order to better filter the air. This was later modified to include its own air supply, leading to World War I era gas masks
he First World War brought about the first need for mass-produced gas masks on both sides because of extensive use of chemical weapons. The German army successfully used poison gas for the first time against Allied troops at the Second Battle of Ypres, Belgium on April 22, 1915. An immediate response was cotton wool wrapped in muslin, issued to the troops by May 1. This was followed by the Black Veil Respirator, invented by John Scott Haldane, which was a cotton pad soaked in an absorbent solution which was secured over the mouth using black cotton veiling.
Seeking to improve on the Black Veil respirator, Clunky McPherson created a mask made of chemical-absorbing fabric which fitted over the entire head canvas hood treated with chlorine-absorbing chemicals, and fitted with a transparent mica eyepiece. McPherson 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; McPherson was appointed to the War Office Committee for Protection against Poisonous Gases. More elaborate sorbet compounds were added later to further iterations of his helmet (PH helmet), to defeat other respiratory poison gases used such as phosphine, phosphine and chlorination. In summer and autumn 1915, Edward Harrison, Bertram Lambert and John Add 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
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
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 defense 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
What You Should Know in Deciding Whether to Buy Escape Hoods, Gas Masks, or Other Respirators for Preparedness at Home and Work
Some employers and consumers are considering purchasing escape hoods or other respirators to protect themselves against potential terrorist threats, including biological and chemical substances. This guidance will provide information on what respirators are, how they work, and what is needed for a respirator to provide protection.
Is buying an escape hood or other type of respirator the best way to protect myself, my family, and/or my employees?
If available and used correctly, a respirator can selectively reduce the exposure you might otherwise receive. Respirators have been used for many years in the workplace, where employers have programs to make sure the proper masks are selected and that the respirator fits. When consumers use respirators, they don’t have such support, so this fact sheet includes lots of background information to help consumers understand the limitations and cautions that need to be considered. The goal is to avoid unintended problems that might occur through lack of understanding or a false sense of security.
As a first step, plan how to respond if an emergency happens. A respirator is only one small part of that plan. There may be situations in which it’s simply best to stay where you are and avoid any uncertainty outside, a process known as “shelter-in-place,” as a means of survival. Use available information to assess the situation. If you see large amounts of debris in the air, or if local authorities say the air is badly contaminated, you may want to take this kind of action. The US Department of Homeland Security offers information on shelter-in-place and other emergency planning recommendationsexternal icon on its Internet site, and through a toll-free number, 1-800-BE-READY.
Respiratory protection is effective only if:
Each type of respirator can come in several varieties, each with its own set of cautions, limitations, and restrictions of use. Some respirators require testing to ensure a tight fit to the face, and should not be used with facial hair. Others use a nose clip and mouthpiece, which is clenched between your teeth, similar to a snorkel. Some respirators prevent the user from talking while others have speaking capabilities. Every respirator contaminated with hazardous chemicals should be decontaminated and disposed of properly.
All respirators require training to be properly used. Sometimes you can practice using your own respirator. Some escape respirators come in a package that must remain sealed until use, so you need to be trained using a special “practice” version. Training is extremely important in regard to the storage, maintenance, use, and discarding of the respirator. This information is provided by the supplier of the respirator (i.e. seller, distributor, or manufacturer).
If you do not use a respirator correctly, it is very likely that it will not protect you-and may even hurt you. The following information will help you understand what a respirator is, and how it should be used.
What is a respirator?
A respirator is a device to protect you from inhaling dangerous substances, such as chemicals and infectious particles. There are several different types of respirators, as described below.
Escape respirators are designed to be used only in an emergency, and only to escape from a dangerous area to a safe area. There are several escape respirators on the market. Many of them use a hood with a neck seal instead of a face piece. They are typically designed for one-time use for a short period, typically 15 minutes to 1 hour. They may be available in a variety of sizes and will fit most adults. Individuals with small or very large neck sizes may not be able to use some escape hood designs-check the supplier product information before purchasing.
Particulate respirators are the simplest, least expensive, and least protective of the respirator types available. These respirators only protect against particles. They do not protect against chemicals, gases, or vapors, and are intended only for low hazard levels. The commonly known “N-95” filtering facepiece respirator is one type of particulate respirator, often used in hospital to protect against infectious agents. Particulate respirators are “air-purifying respirators” because they clean particles out of the air as you breathe. Even if you can’t see the particles, there may be too many in the air for this respirator to provide adequate protection.
Chemical Cartridge/Gas Mask Respirator
Gas Mask Respirator
Gas masks are also known as “air-purifying respirators” because they filter or clean chemical gases and possibly particles out of the air as you breathe. This respirator includes a face piece or mask, and a filter/cartridge (if the filter is in a metal shell it is called a “canister”). Straps secure the face piece to the head. The cartridge may have a filter to remove particles (such as a biological weapon), charcoal (to remove certain chemicals), both, or other parts. When the user inhales, air is pulled through the filter.
Gas Masks are effective only if used with the correct cartridge or filter (these terms are often used interchangeably) for a particular biological or chemical substance. Selecting the proper filter can be a complicated process. There are cartridges available that protect against more than one hazard, but there is no “all-in-one” filter that protects against all substances. You need to know what hazards you will face in order to be certain you are choosing the right filters.
Powered Air Purifying Respirator
Powered Air-Purifying Respirator
Powered air-purifying respirators use a fan to blow air through the filter to the user. They are easier to breathe through and they need a fully charged battery to work properly. They use the same filters as gas masks, so you need to know what the hazard is, and how much of it is in the air.
Self-Contained Breathing Apparatus
Self-Contained Breathing Apparatus
Self-Contained Breathing Apparatus is the respirator commonly used by firefighters. These use their own air tank to supply clean air, so you don’t need to worry about filters. They also protect against higher concentrations of dangerous chemicals. However, they are very heavy (30 pounds or more), and require very special training to use and to maintain them. Also, the air tanks typically last an hour or less depending upon their rating and how hard you are breathing.
The following questions and answers provide additional information for use in selecting and using gas mask and escape respirators.
At the end of this Fact Sheet, you will find a list of questions you should ask before purchasing a Gas Mask or Escape Respirator.
Can I buy any Gas Mask or Escape Respirator and expect it to protect me from anything that might happen?
These respirators must be selected for protection against a specific hazard.
The cautions, limitations and restriction of use provided with the respirator must be strictly followed. If your mask does not make a tight seal all the way around your face when you inhale, you may breathe contaminated air that leaks around the edges of the face seal. Anything that prevents the face mask from fitting tightly against your face, such as a beard or long sideburns, may cause leakage. Some respirators come in different styles and sizes, and fit different people differently because people’s faces have different shapes. You also need training to know how to correctly put the mask on and wear it correctly. This information should be provided by the supplier of the respirator.
If I have the right cartridges/filters for a certain hazard, and my mask fits, will they always protect me against that hazard?
Gas Masks and Escape Respirators reduce exposure to the hazard, but if the exposure is such that it goes beyond what the filter is capable of handling (either because the amount of toxic gas or particles is more than what the filter is designed to handle, or because the exposure lasts longer than what the filter is designed to handle), the filter may not be effective in providing required protection. Also, there may be a small amount of leakage even if the fit of the respirator has been tested. If so, and if there is large amount of a toxic chemical in the outside air, even that small leakage can be dangerous.
Can anyone wear a respirator mask?
Breathing through a respirator is harder than breathing in open air. People with lung diseases such as asthma or emphysema, elderly people, and others may have trouble breathing. Some people with claustrophobia may not be able to wear a mask or hooded respirator. Some people with vision problems may have trouble seeing while wearing a mask or hood (there are special masks for people who need glasses).
Will a gas mask protect children?
There are a variety of problems with fit and use of respirators for children, especially small children and infants. For example, currently available masks are unlikely to fit the faces of small children and infants. As with respirator use by anybody, fit-testing, training, and proper use and maintenance are essential.
Will my cartridge/filter and respirator mask protect forever?
Cartridges, filters, and masks get old. Cartridges can have a limited life. If the filter cartridges that attach to the mask are outdated, have been open to the air or are damaged, you are not protected. Cartridges that contain charcoal or other chemicals for filtering the air should be in air-tight packages. If cartridges are open or not packed in air-tight packaging, they should not be used. Even cartridges in original packaging have expiration dates that should be checked before purchase. Also, over time your mask can get old and break down. Keep your mask in a clean, dry place, away from extreme heat or cold. Inspect it according to the manufacturers instructions.
If I wear a Gas Mask correctly, am I completely safe?
The filter cartridges protect against only certain inhaled airborne substances. Some dangerous chemicals are absorbed through the skin. Properly selected and worn gas masks and escape respirators must be combined with protective clothing to completely prevent injury from these chemicals.
Will a Gas Mask protect me if there is not enough oxygen in the air?
Gas Masks do not provide oxygen. If used in an environment with low oxygen levels, such as a fire, you are in danger of suffocation.
Will a Gas Mask protect me if there is a fire?
It’s important to read the manufacturer’s information if your main concern is to be able to escape from a smoke-filled building. Smoke particles can rapidly clog gas mask filters, and filters with special chemicals are needed to protect against carbon monoxide and other gases that may occur in a fire. Not all gas masks and escape respirators protect against these hazards. Some components, including hoods and face pieces, of many of the gas masks and escape respirators may melt if exposed to a fire.
Once I put on my Gas Mask or Escape Respirator, how long will it last?
That depends on how much filtering capacity the respirator has and the amount of hazard in the air – the more chemical or biological hazard in the air (higher concentration), the shorter the time your filter will last. There is no absolute time limit, and it will vary by each respirator model’s capacities. That’s why your emergency plan must include some idea of how to get to a safe area before the filtering capabilities of the mask runs out.
How do I know a respirator will protect me against the hazards it claims to protect against?
No agency in the U.S. tests and certifies respirators for use by the general public, however, the National Institute for Occupational Safety and Health part of the Centers for Disease Control and Prevention (CDC), tests and certifies respirators for use by workers to protect against workplace hazards. Respirators certified by NOSH will say “NOSH Approved” and may have a certification number. However, NOSH only certifies respirators against specific hazards. Just because a respirator is certified does not mean it will protect against ALL hazards. NOSH-certified respirators are supplied with Approval Labels that identify the hazards that the respirator is approved to protect against. If you are buying a respirator, you should check the Approval Label to be sure that it has been certified against the hazards you want protection against.