A respirator (commonly known as gas mask , the breathing mask , in the military and civil protection area CBRN -Schutzmaske or NBC protective mask , in the NVA force protection mask ) is a face partially or completely covering protective mask . It serves to protect the wearer from airborne pollutants ( respiratory toxins ) or pathogens . The various devices are divided into full face masks (standardized according to EN 136) and half and quarter masks (EN 140). Among the particle-filtering half masks include FFP masks ( English : filtering facepiece , be filtered facepiece). Such respiratory protection systems are required where it is necessary to prevent substances that are hazardous to health from entering the airways ; For example, in rescue services, fire brigades , technical relief organizations , fire detection and workplaces where respiratory toxins (chemical substances, microorganisms, dusts) can occur, e.g. As in cleaning of tanks .
The breathing mask can be made of rubber , silicone rubber or a plastic . In the past, leather or fabric , sometimes with a rubber cover, were also used. It is to be distinguished from a medical mouth and nose protection (MNS, also called "surgical mask" or "mouth protection") and self-made everyday masks (an overview can be found under protective mask ).
Respiratory protection masks can be used in conjunction with compressed air breathing systems independently of the ambient air or with respiratory protection filters depending on the ambient air. With the circulating air-dependent version, the respiratory protection filter can either be attached directly to the mask or connected to it via a hose. Multiple filters or a blower can also be attached for ease. A distinction is made between normal pressure masks and positive pressure masks . In the meantime, a respirator with integrated data glasses has also been developed to enable navigation in smoky rooms. The system is based on room localization electronics.
The beak-shaped, herb-filled masks of the medieval plague doctors can be seen as the first forerunners of the respiratory masks .
The French Jean-François Pilâtre de Rozier did pioneering work in the field of respiratory protection when he presented the construction of the first suction hose respirator with a respirator in 1785.
Gas masks were introduced by all warring parties during the First World War as part of the development and use of chemical warfare agents to combat ground forces. Worth mentioning are the American inventor Garrett Morgan and the Canadian doctor Cluny MacPherson . The airways and eyes in particular should be protected by the gas mask. Respirators and simple breathing masks, which mainly protect the wearer from dust, were already in use before, mainly in mining. The first gas mask with a carbon filter was invented in 1915 by the Russian scientist Nikolai Dmitrijewitsch Selinsky .
Models from the First World War were made of impregnated fabric and often had no filter or were only equipped with a cotton filter. In the further course of the war, chemical-absorbing materials were used. In addition, special masks were developed for horses , which still played an important role in the warfare of the time.
Before the Second World War , various states developed so-called people's gas masks to protect the civilian population. Since the Second World War there have also been special gas masks and protective gas hoods for children.
Full face mask
Full masks usually consist of the mask body made of silicone or rubber, one or two viewing panes in a sealing frame, the exhalation valve, sometimes the strap, the harness (spider), an inner mask or air ducts, a speech membrane and the connector for a regulator ( regulator ) or Breathing filter.
Two separate viewing panes are mainly used in the military sector to make it easier to transport the mask.
The harness can - especially in embodiments for firefighters - also consist of a system, the mask and helmet together braced ( H ELM M asken- K ombination). In the military sector, flexible hoods made of rubber are sometimes used instead of straps.
A strap is attached to some masks so that the mask can be hung around the neck; Especially in aviation, a bracket made of plastic or metal can also be attached in order to be able to hang up the mask.
The inner mask is used to reduce functional dead space . Breathing air is brought into the mask body via control valves, which brushes over the lens and thus prevents fogging. If an inner mask is not used, air ducts are installed instead, in which the air can also sweep along the windows.
In the past, so-called clear panes were used to prevent fogging . These were thin celluloid discs that were coated on the inside with a moisture-absorbing gelatin layer. The clear disks were fastened in front of the eye disks by means of a retaining ring (snap ring ) .
A distinction is made between rigid and semi-rigid (flexible) masks. A special variant of the full face mask is the hood, as it is offered for escape and work purposes (sandblasting). It offers extended protection and comfort and leads over to the helmet and full protective suit .
A half mask covers the nose and mouth. The eye area is left out here, so that it cannot be used without protective goggles in an ambient atmosphere with pollutants that can cause irritation or damage to the eyes. In contrast to the full face mask, the sealing line here runs over the nose area, which is difficult to seal. The basic structure corresponds to that of the full face mask, but the half face mask has no window and no inner mask. Areas of application are, for example, dust protection masks for grinding work in the trade or on construction sites, for silo inspections, in mining or against aerosols , e.g. B. when applying paint (only water-based paints!) With a spray gun or airbrush . Furthermore, certain particle-filtering half masks are assigned the property of protecting themselves against various pathogens, such as B. SARS-CoV-2 , at least partially to protect. Particle-filtering half-masks usually consist entirely of the filter material.
Particle-filtering half mask ( English filtering face piece , FFP , dust mask , dust mask or respirator filter ) protect depending on the design of inhalation of particles and aqueous or oily aerosols . They do not offer any protection against gases and vapors, even if they are provided with an inlay made of activated carbon . This insert serves to protect against unpleasant but harmless organic odors (e.g. for handling slaughterhouse waste, in animal breeding or waste disposal). Protection against gases can only be achieved with special gas filters. Filtering half masks are mostly made entirely of non-woven material with elastic bands and a malleable nose clip to optimize the adaptation to the face.
When used properly, the masks with test certification provide reliable protection against respirable dusts and liquid mists within their respective area of application. In addition to the supporting filter material, they have layers made of an electrostatic material ( electret , see also electret filter ). Small dust particles and drops of liquid are bound by electrostatic forces. However, the electrostatic effect decreases after some time due to the accumulation of dust, and the deposits also lead to a noticeable increase in breathing resistance.
Unless otherwise stated by the manufacturer, FFP masks are generally intended for one-time use within a work shift of a maximum of eight hours for reasons of hygiene. In the case of reusable masks, the filter fleece or the particle filter must also be replaced after eight hours and the mask body disinfected. In Germany, the occupational safety committees at the Federal Ministry of Labor and Social Affairs (BMAS) recommend wearing a protective mask with a breathing valve for a maximum of 120 minutes, without a breathing valve for a maximum of 75 minutes; Allow 30 minutes to recover before using it again.
Classification in Europe
A classification is made according to the European standards (EN 149) in three classes. The overall leakage of a mask, which is made up of the leakage points on the face, the leakage on the exhalation valve (if present) and the actual filter passage, is used for assessment.
|class||Total leakage||Protection against particle sizes (max. 0.6 μm) and area of application|
|FFP-1||maximum 25%, mean values not greater than 22%||for non-toxic and non-fibrogenic dusts; maximum concentration up to 4 times the maximum workplace concentration|
|FFP-2||at most 11%, mean values not greater than 8%||Protective effect at least 95%; for harmful dust, mist and smoke; Filters for solid and liquid particles; against harmful substances, the concentration of which is up to 10 times the maximum workplace concentration.|
|FFP-3||maximum 5%, mean values not greater than 2%||at least 99%; Protection against toxic substances as well as against droplet aerosols, carcinogenic or radioactive substances, enzymes, microorganisms (viruses, bacteria, fungi and their spores); against harmful substances whose concentration is up to 30 times the maximum workplace concentration.|
The following additions are also possible:
|S (solid)||solid aerosols and particles|
|SL||aqueous and oily aerosols and particles|
|V||with exhalation valve to reduce breathing resistance|
The additional designations S and SL were omitted with EN 149 from 2001 (EN 149: 2001). Products tested according to this standard protect against both fine dust (S) and liquid aerosols (SL), so that there is no differentiation between S and SL.
According to EN 149: 2001 + A1: 2009, additional letters are added to the designation FFP X (X: 1, 2, or 3):
- D: Successful dolomite dust storage test: The test consists of exposing the particle-filtering half-mask to a sinusoidal breathing simulation while the sample is surrounded by a known concentration of dolomite dust in air. Following the exposure, the breathing resistance and the filter permeability of the sample of the particle-filtering half-mask are measured. The packaging of those particle-filtering half masks that have passed the storage test with dolomite must also be marked with the letter "D". This letter follows the class designation after a single space.
- R and NR ( reusable / reusable and not reusable / for single use ): If the manufacturer also fulfills the condition that disinfection of the FFP mask is possible and described, he can mark it with "R" for reusable . An “NR”, on the other hand, means that use is limited to the duration of one shift.
Part of the test according to EN 149 is heating the masks in a dry atmosphere to 70 (± 3) ° C for 24 hours.
In direct care of patients with confirmed or probable COVID-19, FFP2 masks should preferably be worn (protection from aerosols and droplets). If FFP2 masks are not available, MNS should be worn (protection against droplets). Respiratory protection masks (FFP3) should be worn for all activities that involve high levels of aerosol production (e.g. intubation or bronchoscopy).
Simple designs without standard Prüfstempelung (the former name coarse dust mask is no longer allowed; instead, they are now often under the name mouth guard or face mask to find commercially) protect through their pore size only against liquid droplets and coarse dust, which in any case not until the lung advance. So at best they offer protection against a droplet infection in the case of colds or other diseases that can be transmitted in this way. In the event of dust accumulation, they only protect against grinding your teeth; They do not protect against the health consequences of dust exposure, but rather increase the risk through their collecting effect.
Marking of marketable masks from the USA, Canada, Australia, New Zealand and Japan
In the United States, the National Institute for Occupational Safety and Health (NIOSH) issued the standard 42 CFR Part 84, which specifies the permitted protective masks ( NIOSH-approved particulate filtering facepiece respirators ) in seven classification levels (N95, Surgical N95, N99, N100, R95, P95, P99 and P100) (United States NIOSH-42CFR84). The letter N means that the mask marked with it is not oil-resistant, while an R indicates partial and P a strong oil resistance. The numbers stand for the respective filter performance of airborne particles; so filter z. B. Masks with the code 95 at least 95%; For masks with the code number 100, at least 99.97% filter performance must be proven.
The masks that correspond to this standard must also be provided with additional labels, e.g. B. the logo or the name of the NIOSH and the model number. According to the Federal Institute for Occupational Safety and Health (BAuA), the mask of the "N95" standard " essentially corresponds to the requirements for FFP2 masks."
The NIOSH certified masks are also used in Canada. The standard Z94.4-11 Selection, Use and Care of Respirators of the Canadian Standards Association (CSA) was also published there.
In Australia and New Zealand, the standards organizations Standards Australia and Standards New Zealand issued a common standard, the AS / NZS 1716-2012 Respiratory protective devices . Corresponding masks or their packaging must be marked with AS / NZS 1716. Masks of the P2 standard correspond “essentially to the requirements for FFP2 masks”.
In Japan, according to JMHLW notification 214 (2018), the DS marking is one of several standards for dust masks; The DS2 standard “essentially corresponds to the N95 standard in the USA”. Before they can be placed on the market, manufacturers or importers must have the national Japanese type approval for the respective products.
Defective Products Database
Information on defective products can be found on the website of the Federal Institute for Occupational Safety and Health. The Federal Institute for Occupational Safety and Health (BAuA) publishes product recalls, product warnings, prohibition orders and other information on individual dangerous products that may be used in Germany in its "Dangerous Products" database. a. are regulated by the Product Safety Act (ProdSG).
Use of FFP masks
FFP masks are used as part of personal protective equipment in the context of occupational safety in areas in which there are harmful substances in the air. Masks without a valve filter both the inhaled air and the exhaled air and are therefore suitable for personal and external protection. A mask with an exhalation valve only filters the inhaled air, which is why it is only used for self-protection. FFP2 and FFP3 masks are used primarily in intensive care units to protect employees from infection.
Since incorrectly putting on and taking off personal protective equipment (PPE) can lead to undesired contamination, a special procedure is indicated in each case, including when handling protective masks. In connection with the COVID-19 pandemic, the Robert Koch Institute issued recommendations, including instructions for specialist staff on how to safely put on and take off a respirator and protective goggles .
Reusability of FFP masks
Reusable masks of type FFP 2 or 3 are marked with the letter "R" for reusable and are CE-certified; they meet the EN standards 136, 140, 143, 149, 1827, 12941 or 12942. The manufacturer must provide test documents, instructions for handling and disinfection . In addition, appropriate disinfectants and replacement particle filters must be available, as the latter have to be replaced after being soaked or worn for a long time.
In some clinics, in order to counteract a deficiency, FFP3 masks that are mechanically in order are also reprocessed, sterilized and reused. However, they are also sometimes downgraded one level from FFP3 to FFP2 for security reasons. For certain reprocessing processes of comparable single-use N95 masks, a working group from the Centers for Disease Control and Prevention (CDC) was able to show a reduction in the filter effect of up to 40%, while other processes largely retained the filter effect. Based on existing research results on the reprocessing of N95 protective masks, the CDC has published recommendations for the American healthcare system to implement a limited reprocessing. As part of the COVID-19 pandemic, an interdisciplinary research consortium was formed with N95DECON , which deals scientifically with the decontamination and reusability of masks and regularly publishes the resulting findings.
Exemption for Germany in the Covid 19 pandemic
In March 2020, the Robert Koch Institute (RKI) issued an option for action, which is provisionally valid until August 31, 2020, to address the increasing shortage of mouth and nose protection (MNS) and FFP2 masks in connection with the COVID-19 pandemic to meet. This regulates the resource-saving use of mouth and nose protection (MNS) and FFP masks in health care facilities in the event of delivery bottlenecks. The recommendation was drawn up in coordination with the ad hoc working group on SARS-CoV-2 of the Committee for Biological Agents (ABAS) and in cooperation with the Federal Ministry of Labor and Social Affairs.
This describes the possibility of re-using MNS and FFP masks in "declared emergency situations" under certain conditions. What is necessary in advance is a "competent risk assessment or risk assessment by the employer on site, taking into account the local conditions, including the hygiene staff, the company medical service and, if necessary, in consultation with the responsible health department." Safe handling is necessary to avoid the risk of infection for To keep employees low. Since the outside of the used mask potentially contains pathogens, contamination of the wearer must be avoided when it is put on again.
According to the submission of the BMAS and the Federal Ministry of Health (BMG) for the federal government's crisis team of March 31, 2020, the exemption regulations for reuse were limited to a maximum of six months.
The BMAS and the BMG temporarily recommended a process for heat inactivation using dry heat at 65 to 70 ° C for 30 minutes. In May, the Federal Ministry of Health's respiratory protection team declared that the procedure described could no longer be recommended. A higher temperature and a longer time may be necessary.
Expedited examination due to COVID-19
In response to Recommendation (EU) 2020/403 of the European Commission in mid-March 2020, the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) and DEKRA Testing and Certification GmbH developed a rapid test for respiratory masks: This is how the acute shortage of European approved Products with so-called pandemic respiratory protection are limited for a short time. In this way, it is possible for the authorities of the EU member states to also buy respiratory masks without CE marking in an organized manner and to provide them for a limited period of time. The prerequisite is that the respirators guarantee an appropriate level of health and safety. In addition, in the event of an acute shortage, the masks should only be available to medical and nursing specialists for the duration of the health threat posed by the COVID-19 pandemic . The approval of respiratory masks based on these principles is no longer valid after twelve months. There is the option of offering the product as regular respiratory protection in the European Union after this period has expired, if it has been subjected to a full test according to EN 149 and a conformity assessment according to the Regulation on Personal Protective Equipment (EU) 2016/425 by a designated person Place is done.
Normal pressure mask
The pressure inside the mask corresponds exactly to the ambient pressure - this is also the difference to the overpressure mask . The pressure inside is controlled and adjusted by the regulator. With normal pressure masks, the connection for the regulator is usually marked in blue or black.
A disadvantage of this system is that in the event of a slight leak in the mask, pollutants from the atmosphere can get into the mask when inhaled, as there is briefly a slight negative pressure until the regulator compensates this again; however, if there is a leak, there cannot be a major loss of air - possibly unnoticed - (see ÜD mask).
In contrast to the normal pressure mask, the regulator ensures an overpressure in the breathing mask. The overpressure in the mask is around 4 mbar.
This is also the main advantage of the positive pressure mask : the wearer of breathing apparatus can breathe in more easily. In the event of slipping or a slight leak, no combustion gases or other gaseous pollutants (use of dangerous goods) can get inside the mask. Blowing off the breathing air through the leak is also the disadvantage: the air consumption in the event of a leak can increase significantly compared to a normal pressure device and thus considerably reduce the operating time, which has already led to incidents in the past. Regulations for the use of respiratory protection (fire brigades: FWDV 7) require, among other things, regular checking of the air supply. Respiratory protection monitoring (regular pressure queries, time monitoring) and a security team provide additional security for the fire brigades.
Use with regulator
When the person wearing the respirator begins to breathe, he creates a negative pressure in a tight-fitting respirator. Via the regulator ( breath- controlled metering device), the pressure reducer via the regulator then feeds the appropriate amount of air into the mask. Depending on the device type, this mean pressure is between 4.5 and 8.0 bar. The breathing air enters the mask body via the inhalation valve and flows past the lens. This effect prevents the lens from fogging up. The breathing air now enters the inner mask via the control valves and is breathed in. When you exhale, the inhalation valve closes and the exhaled air flows out through the exhalation valve. In the case of the overpressure mask, there is also an overpressure of 3.9 mbar in the mask due to a spring-loaded exhalation valve. This means that if the mask leaks, no respiratory toxins can get into the mask. The inhalation resistance is lower in contrast to the normal pressure mask. But the exhalation resistance is slightly increased by the spring-loaded exhalation valve.
Use with respiratory protection filter
When breathing protection filters are used, the inhalation resistance has a negative impact because the person wearing the breathing apparatus has to bridge this resistance with his breathing. If he only inhales and exhales very shallowly, an increased proportion of carbon dioxide can collect in the mask and lead to unconsciousness after a while, the so-called airtrapping. The same danger exists with rebreather devices with pendulum breathing. Half masks may only be used with respiratory protection filters.
Breathing connections for normal and positive pressure air masks
Differences in the connections of normal pressure and positive pressure masks:
- Normal pressure mask
- Round thread connection according to EN 148-1 (Rd 40 mm × 1/7 "), unloaded exhalation valve
- Overpressure mask
- Pointed thread connection according to EN 148-3 (M 45 mm × 3 mm), spring-loaded exhalation valve, red marking of the connection piece
- Overpressure mask
- ESA (standard plug connection) according to DIN 58600
There is also the option of using the plug connection.
There are always difficulties for those who wear glasses . Ordinary glasses with the temples that lead to the ears cannot be worn in this case, as the mask would otherwise leak at this point. So-called " gas mask goggles " are also not permitted for use by fire fighters. Instead of the temples, these have elastic bands that run over the ears in the same way as glasses. These rubber bands also impair the sealing line of the respirator. Today's constructions are clamped into the mask using a wire frame. The lenses (in the case of two-eyed masks) are rarely exchanged for suitable optical glasses.
Leaks are also caused by beards or whiskers, a shave in the area of the sealing lips of the respirator is necessary for safety reasons. A leak can be detected metrologically just a few hours after shaving. Therefore, beards are sometimes not approved for use with breathing apparatus.
Modern masks, which not only protect against gases but also against dust-like ABC warfare agents or CBRN warfare agents , are called ABC protective masks or CBRN protective masks . The name implies a (limited) protective effect in a Tomaren, b iologischen and c hemischen attacks. In the Austrian Armed Forces, the joke name "Zuzz" is used for the NBC protective mask, which aims at the similarity of the filter to a pacifier . Suitable filters are available for the various gases and pollutants.
Historically, horses were still used during the First World War. The development of respiratory protection for these ran from sack-shaped masks around the mouth to those with two tampons that penetrated the nostrils in a conical shape.
German gas mask from the Auergesellschaft with a carrying rifle, around 1941
An AEF- American soldier demonstrates the gas masks for man and horse, around 1918
GP-5 gas mask : Soviet protective mask manufactured between 1962 and 1989
- Everyday mask
- Mouth and nose protection (medicine)
- Particle filter classes
- Manufacture of protective equipment and medical devices in the COVID-19 pandemic
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