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Gas masks - the most important mean of respiratory protection.

2022-05-12
Gas masks - the most important mean of respiratory protection.

Gas masks, the basis of personal NBC protection

Artificially biological and chemical threats burdening humanity have been known for centuries. In ancient times, besieged cities were intentionally infected with carrion, and in the Middle Ages, Mongolian troops used smoke screens during their invasions, in order to camouflage their movements and shock the enemy with suffocating agents at the same time. Even before the First World War, the ban on the use of chemical warfare agents (CWA) was discussed in the international arena, by introducing appropriate provisions in The Hague Conventions of 1899 and 1907.

Despite earlier attempts, after the outbreak of World War I, the parties to the conflict quickly began to use chemicals widely in order to break the opponent's resistance at specific points and break out of the frontal stalemate. It was only then, with the massive use of chemical warfare agents on the front lines of the Great War, that the issue of respiratory protection was seriously raised.

How gas masks were created, and how did they develop?

The earliest gas masks were simple devices focused only on isolating the user from harmful vapors. They took the form of airtight bags, designed to be worn on the head, made of a textile material soaked in reagents, known to bind specific poisonous gases, with a visor and an exhalation valve. The research and experiments of Nikolay Zielinsky, a professor of organic chemistry from the Russian Empire, resulted in the development of a filter that allowed for easier flow and more thorough cleaning of the air. Those were simple systems, based on the usage of carbon inserts, but at least they made it easier for the soldier to breathe.

World War I era gas masks allowed soldiers for only a short stay in the contaminated area and for basic movement in order to leave it. Visibility from them was too low to effectively operate the weapon, communication was hampered by the lack of voice-conducting systems, and the question of thirst-quenching while in the mask was non-existing at all. An interesting fact is, that special masks for frontline animals were quickly developed. Especially important were horses and mules, which were the basic means of front-line transport, or dogs, commonly used as messengers, as sentries, for the location of the wounded, and as an anti-rat means.

In the interwar period, there was a boom in the development of protection against CWA. As a result of the trauma caused by their use at the front lines, there was a fear of a chemical attack on the home front and civilian targets. Therefore, many paramilitary organizations were created, focused on training in contamination removal and education of the civilian population. In the armed forces, each soldier received his own gas mask, and those became more and more sophisticated: those intended for communications personnel had more efficient voice transmission systems, those for chemical troops had greater resistance, and even special masks were created, designed to be used for the casualties with head wounds. Special civilian models were developed, with simplified structures, but easier construction and lower production costs, and even special masks and suits for children, including those as small as babies.

The Second World War, however, did not turn out to be a chemical conflict, but it left behind another threat - the threat of nuclear weapons and the radiation that accompanied them. PPE had to be adapted to it. The extension of the range of weapons of mass destruction to include nuclear weapons shaped the threat category, that exists today: NBC - Nuclear-Biological-Chemical. It was with this in mind that subsequent generations of gas masks and combined filters were developed, from the Cold War era up to the present day.

With the continuous development of the level of protection, ergonomics have also been improved. After 1945, the masks, which previously allowed for moderately effective weapon handling and communication, were replaced by new generations, more comfortable for long-term use. The quality of the material, the ways of wearing it, and the clarity of the voice were improved, but also the systems of administration of fluids and ambidextrous filter assembly became widespread. Hearing protectors and communication systems could also be worn at the same time. As a result, combat operations in protective clothing became easier and the soldier's effectiveness increased.

"The Elephant and the Polish Question" - case of a slang word for the gas mask

In the Polish language, gas masks are known as "słoń" (or "słonik"), which means "elephant". It is a slang word originating from the communist-era military and is derived from the gas masks of soviet origin, mainly models from the ShM41 family, characterized by closed headpieces and rubber hoses (the "elephant's trunk") connecting them with combined filters. The quality of the voice and the sounds of breathing in those masks were also a factor, being compared to the sounds made by these majestic animals. "Elephant" masks were the most widespread mean of individual respiratory protection throughout the period of the People's Republic of Poland, both in the military and civil sectors.

The basic and correct name, however, remains the "gas mask".

What are the types of gas masks we distinguish in terms of operating principles?

In terms of the operating principles, there are insulating and filter gas masks.

Insulating gas masks operate in a closed circuit. They recycle the exhaled air. Carbon dioxide and water vapor are converted into oxygen in the so-called regenerative canisters, through an exothermic reaction caused by contact with selected chemical compounds. The oxygen is then collected in the breathing bag, from where it is delivered to the user's lungs. Regenerative canisters are disposable and operate continuously after activation. Some insulating gas masks are combined with an oxygen cylinder. Then the regenerative canister serves to maximize the protection time. Insulating masks are highly specialized devices, characterized by great protective properties and duration of operation, but nevertheless a complex structure, high weight, and high price. They are typically found in the use of emergency services such as the fire brigade or mine rescue.

Filter gas masks are the most common type. They are based on filtering the air inhaled from the outside. They consist of a facepiece and a combined filter. Filters have many types, adapted to specific threats and the required level of protection. Due to their easy assembly two-part design, simplicity of usage and transport, and adequate level of protection for most applications at the same, they are the most widespread gas masks in the military, Civil Defense, and civilian use. It is very important to know that filter masks, as devices using an external air source, should not be used when the oxygen content in the air goes below 17%.

Among the filter masks, one more type can be distinguished, i.e. the escape hood. It is a lightweight, disposable device that provides short-term protection for the time required for an escape from the danger zone. It takes the form of a hood, made of thin and impermeable material, with a visor and permanently attached combined filter.

What types of gas masks do we distinguish in terms of size?

In terms of the size of the protected area, half-masks and full-face masks are distinguished.

Half-masks cover the nose and mouth. In order to fully protect the face, they require the simultaneous use of a visor, and it can be selected according to the needs. They have one or two threaded sockets for the installation of a filter or combined absorber. Such masks are intended mainly for use in the case of operation in dust and aerosols, especially during paintwork or sandblasting. However, with an appropriate combined filter and in conjunction with adequate eye protection, which best should be safety goggles, they have a level of protection that allows them to be used as an intermediate protective measure, between improvised respiratory protection and full-scale gas masks.

Full-face masks protect the entire face, and the mouth, nose, and eyes cover to form a coherent whole. They can have one or two filter slots. They can also be connected to the combined filter with a flexible hose. Eye protection in such masks consists of a panoramic visor or separate glasses made of transparent, high-strength material. The flexibility of the use of full-face masks lies in the choice of combined filters available. They can be universal or specialized against a particular threat. They have different levels of protection, depending on the concentration and the required maximum protection period.

Full-face gas masks are the best compromise between size and readiness to put on immediately. In addition to the military use as the basic means of individual NBC protection, they are also used by rescue services as escape devices and means of protection for short-term operations in the danger zone. They can also be used as a face and respiratory protection in the work environment associated with the risk of contact with chemical vapors, aerosols, and dust.

What elements does a modern gas mask consist of?

A modern filter gas mask consists of a facepiece with a headband, a liquid delivery system, and a combined filter. A carrying bag and a canteen are also included.

The facepiece, the main structural element and the base of the mask, has a half-mask with a valve and thread for connecting a combined filter, a voice chamber for conducting and amplifying the voice, an exhaust system to drain the exhaust air, a panoramic visor or glasses, a liquid delivery system consisting of a sealed valve and a rubber supply hose (often compatible with existing water containers standards such as Camelbak), and straps to tighten and hold the mask on the head.

Each model of a gas mask has several sizes, based on the specific dimensions that need to be measured in order to find the best-fitting version. In the case of masks with a band head-harness, more precise fitting regulation is possible.

The mask usually has one or two slots for mounting external combined filters. The two-point versions allow the installation of a single filter while sealing the opposite opening, to allow the right- or left-hand usage of the weapons, or the installation of two combined filters of the same type to achieve a longer protection time.

Modern combined filters take the form of cylindrical containers made of thin sheet metal or plastic, with a threaded montage. The most popular montage standard is 40 mm STANAG 4155 / EN 148-1.

What is a combined filter?

Modern gas masks are designed to protect against many threats. The basis, however, is to use them with appropriate combined filters. They consist of two components: a filter and an absorber.

Filters are designed to protect against dust particles and liquid aerosols. The protection value is expressed in relation to the toxicity level of a specific agent and its Maximum Allowable Concentration (MAC). In terms of the level of protection, there are 3 categories:

  • P1 - Class 1 - Non-toxic and low-toxic dust at concentrations ≥2 mg / m3 MAC - filtration efficiency at the level of 80%
  • P2 - Class 2 - Non-toxic, low- and medium-toxic dusts and aerosols at concentrations ≥0.05 mg / m3 MAC - filtration efficiency at the level of 94%
  • P3 - Class 3 - highly toxic dusts and aerosols, in concentrations ≤0.05 mg / m3 MAC - filtration efficiency at the level of 99.95%

Filters can be used alone and as part of a combined filter. On the casing of the combined filters, the filters are marked in white color and marking of their class. Depending on the category, they differ in internal design. The layers of fibrous material are responsible for filtration. In the past, it used to be asbestos, and today it is glass microfiber.

Absorbers are designed to retain harmful gaseous compounds. They are designed to protect against specific gas families. The most common absorbent material used today is active carbon dosed with various reagents. The absorbers have code and color markings.

  • A - Brown - Organic gases and vapors with a boiling point above 65°C
  • AX - Brown - Organic gases and vapors with a boiling point below 65°C
  • B - Gray - Inorganic gases and vapors, except for carbon monoxide, e.g. chlorine, hydrogen sulphide
  • E - Yellow - Acid gases and vapors, e.g. sulfur dioxide
  • K - Green - Ammonia and organic ammonia derivatives
  • SX - Purple - Substances specified by the manufacturer, the so-called special absorber
  • NO - Blue - Nitrogen oxides
  • Hg - Red - Mercury vapors

In terms of the level of protection, absorbers are divided into 3 classes.

  • Class 1 - Up to a maximum concentration of a toxic gas of 0.1% / 1000 ppm
  • Class 2 - Up to a maximum toxic gas concentration of 0.5% / 5000 ppm
  • Class 3 - Up to a maximum toxic gas concentration of 1% / 10,000 ppm

Marking on the combined filter unit casing consists of the appropriate color, code, and numbering of the protection level class.

What are the civilian uses for gas masks?

Masks, in addition to their main protective function in the event of contact with CWA, can also serve to protect the respiratory system in work environments associated with chemical fumes or the presence of suspended dust, such as varnishing, sandblasting, chimney sweeping, industry related to toxic substances in the form of vapors and aerosols.

The health and safety standards in Poland define 3 cases when it is necessary to work in a gas mask:

  • When the oxygen level in the inhaled air is less than 17% - An insulating gas mask must be used.
  • When work takes place at high temperatures
  • When the amount of dust or hazardous substances in the inhaled air exceeds the relevant standards in this regard

Gas masks are also used in the case of rescue operations, in the case of smoke, carbon monoxide, or other harmful gases, in the case of failures of heating systems, insulating masks are used when the oxygen content in the air is low, and some of them can be used underwater at a depth of up to several meters.

The gas masks themselves are intended for long-term storage, of course under the appropriate conditions, specified by the manufacturers in the user manuals. Being small items, they are a necessary security measure against various threats. However, if you have a gas mask in case of crisis, take care of the service life of the combined filters.

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