Surgical mask
Surgical mask | |
---|---|
Other names | Procedure mask, medical mask, isolation mask, laser mask, fluid-resistant masks, face mask |
A surgical mask, also known by other names such as a medical face mask or procedure mask, is a
Although the material of which surgical masks are made will filter out some viruses and bacteria by trapping the aerosol suspended in breathed air, they only provide partial protection from airborne diseases because of the typically loose fit between the mask edges and the wearer's face.[2][3][4] Surgical masks are distinct from filtering respirators, such as those made to the American N95 standard, which are more airtight and purposefully designed to protect against finer airborne particles.
Evidence from randomized controlled trials that surgical masks reduce infection from diseases such as influenza is weak.[5][6][7] Although a recent very large (over 300,000 people) study found some evidence that they reduced transmission in the community,[8] surgical masks can vary greatly in quality which may make these studies less useful.[3] The effect of surgical masks is partially attributed to filtering out some of aerosol particles that are how airborne diseases are transmitted. Surgical masks are highly variable[3] but the material of which they are made typically filter out more aerosol particles than do cloth masks but much less than does the material of which N95, FFP2 and similar masks, are made.[9] This combined with the poor fit suggests that surgical masks offer some protection to airborne diseases such as COVID-19 but less than do N95, FFP2 and similar masks.
There are standards for the materials masks are made from. For example, the European EN 14683 Type II standard requires the material of the mask to filter particles (mean diameter close to 3 micrometres) containing the bacterium Staphylococcus aureus.[10][11] The bacterial filtration efficiency of the mask material is the fractional reduction in the number of colony-forming units (CFUs) when the aerosol is passed through the material. For a Type II mask under this standard, the material must filter enough of the aerosol particles containing the bacteria to achieve a CFU reduction of at least 98%.
Surgical masks are made of a
In some East Asian countries, masks have often customarily been worn by people who are sick in order to avoid spreading it, to protect against air pollution or allergens, as a fashion statement, or to deter social interaction.[17][18][19] The use of surgical masks during the COVID-19 pandemic was a subject of debate,[20] as mask shortage was a central issue.[21][22]
Function
A surgical mask serves as a mechanical barrier that interferes with direct airflow in and out of respiratory orifices (i.e.
A surgical mask is a
A surgical mask is not to be confused with a
Modern surgical masks are made from paper or other non-woven material and should be discarded after each use.[28]
Physical form
Parameter | Typical unit |
---|---|
Pressure differential, ∆P | cm of H2O / cm2 |
Filtration and exposure | % |
Liquid penetration resistance | mbar
|
Air permeability |
ml/s⋅cm2 at 100 Pa |
Water vapor permeability | g/24 hr⋅cm2 |
Water repellency | grade |
The design of the surgical masks depends on the intended usages. Usually, the masks are
A different type of mask, known as "duckbill" masks, uses a
Small strips of foam or thickened fabric are often sewn along the top edge of the mask to help better seal away exhaled water vapors (which can fog up eyewears and faceshields) and soak up excess perspiration dripping from above. Small bendable metal strips are frequently added to the top edge to better fit over the nasal bridge. Occasionally adhesive tapes can also be added to secure the seal and prevent the mask from slipping up and down.
The masks are typically fastened to the head with
Filter material in the middle layer may be made of
Physical properties and quality
Performance of surgical masks is evaluated based on such parameters as filtration (mask capture of exhaled aerosols), exposure (transfer of aerosols from outside), mask airflow resistance (pressure difference during breathing, ΔP, also known as breathability),[38] liquid penetration resistance, air and water vapor permeability, water repellency (for outer and inner surfaces).[39]
Filtration and exposure is typically measured in
History
Face masks for use in surgery were developed in Europe by several physicians, including
Modern surgical masks began to be used in the 1960s. Their adoption caused
COVID-19 pandemic
During the COVID-19 pandemic, face masks or coverings, including N95, FFP2, surgical, and cloth masks, have been employed as public and personal health control measures against the spread of SARS-CoV-2, the virus that causes COVID-19.
In community and healthcare settings, the use of face masks is intended as source control to limit transmission of the virus and for personal protection to prevent infection.[45] Properly worn masks both limit the respiratory droplets and aerosols spread by infected individuals and help protect healthy individuals from infection.[46][47]
Reviews of various kinds of scientific studies have concluded that masking is effective in protecting the individual against COVID-19.[46][48][49] Various case-control and population-based studies have also shown that increased levels of masking in a community reduces the spread of SARS-CoV-2,[48][49] though there is a paucity of evidence from randomized controlled trials (RCTs).[50][51] Masks vary in how well they work, with N95 and surgical masks outperforming cloth masks,[52] but even cloth masks, with their variability in fabric type and mask fit, provide wearers with substantial protection from particles carrying COVID-19.[53]As the pandemic raged on, healthcare workers were required to continue wearing surgical masks for 12 or more hours a day. This caused the ear loops of the masks to chafe the back of their ears. Ear savers, plastic straps and hooks that go around wearer's heads, were invented to move the ear loops away from the wearer's ears. They could be made on demand by using 3D printing process.[54]
Use
Healthcare workers
A surgical mask is intended to be worn by health professionals during surgery and certain health care procedures[55] to catch microorganisms shed in liquid droplets and aerosols from the wearer's mouth and nose.[28] Evidence supports the effectiveness of surgical masks in reducing the risk of infection among other healthcare workers and in the community.[56] However, a Cochrane review found that there is no clear evidence that disposable face masks worn by members of the surgical team would reduce the risk of wound infections after clean surgical procedures. However, the review cautioned that the studies examined are of low quality and that the result should not be generalized.[7]
Healthcare workers are trained in how to put on, handle, remove, and dispose of surgical masks. For healthcare workers, safety guidelines recommend the wearing of a face-fit tested
General public
In community and home settings, the use of facemasks and respirators generally are not recommended, with other measures preferred such as avoiding close contact, maintaining good hand hygiene,[28] and wearing cloth face coverings.[61]
In Japan and Taiwan, surgical masks have commonly been worn in winter months during the
More recently, due to the rising issue of smog in South and Southeast Asia, surgical masks and air filtering face masks are now frequently used in major cities in India, Nepal and Thailand when air quality deteriorates to toxic levels.[65][66][67] Additionally, face masks are used in Indonesia, Malaysia and Singapore during the Southeast Asian haze season.[68][69] Air filtering surgical-style masks are quite popular across Asia and as a result, many companies have released masks that not only prevent the breathing in of airborne dust particles but are also fashionable.[70][71] In Japan, some use masks as fashion statements, at times as a result of influence from K-pop stars.[18][19]
Surgical masks may also be worn to conceal identity. In the United States banks, convenience stores, etc. have banned their use as a result of criminals repeatedly doing so, but allowed facemasks due to the
Research carried out during the COVID-19 pandemic found that surgical masks increase the attractiveness of the wearer[74][75] and this is more so than other types of masks.[76]
Research and development
Researchers are developing face-masks which may help reduce viral spread better than existing ones and/or have possibly useful properties such as
There also is an experimental face mask with an embedded biosensor that can detect a pathogenic signature (such as one of SARS-CoV-2)[84] and face masks that glow under ultraviolet light if they contain SARS-CoV-2 when the filter is taken out and sprayed with a fluorescent dye that contains antibodies from ostrich eggs.[85]
Other research investigated environmental pollution associated with face mask waste management[86][87][88] and weak spots of masks with product designs of the widely applied FFP standards, in particular variants with exhalation valves.[89]
Regulation
In the United States, surgical masks are cleared for marketing by the U.S. Food and Drug Administration. In the European Economic Area (EEA), surgical masks have to be certified through the CE marking process in order to be commercialized. CE marking of surgical masks involves the respect of many obligations indicated in the Medical Device Regulation (Council Regulation 2017/745 of 5 April 2017 concerning medical devices, OJ No L 117/1 of 2017-05-05).
Surgical masks for use in the US and the EEA conform to
In China, two types of masks are common: surgical masks that conform to YY 0469 standard (BFE ≥ 95%, PFE ≥ 30%, splash resistance) and single-use medical masks that conform to YY/T 0969 standard (BFE ≥ 95%).[40][91] Daily protective masks conforming to GB/T 32610 standard[92] is yet another type of masks that can have similar appearance to surgical masks.
Sensorized Surgical Masks
in 2014, Firat Güder while he was a research fellow at Harvard University, together with Professor George Whitesides, invented a wireless surgical face mask that can monitor breathing of the individual wearing the mask. Their technology relied on disposal paper-based printed sensors which could be integrated into the mask.[93] The technology, which was first published in 2016, led to the formation of a start-up (Spyras Ltd) company to commercialize it which was later acquired.
See also
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Experimental and epidemiologic data support community masking to reduce the spread of SARS-CoV-2, including alpha and delta variants, among adults and children. [...] Mask use has been found to be safe and is not associated with clinically significant impacts on respiration or gas exchange under most circumstances, except for intense exercise. The limited available data indicate no clear evidence that masking impairs emotional or language development in children. [I]n combination with other contextual cues, masks are unlikely to produce serious impairments of children's social interactions. A study of 2-year-old children concluded that they were able to recognize familiar words presented without a mask and when hearing words through opaque masks. Among children with autism spectrum disorders (ASD), interventions including positive reinforcement and coaching caregivers to teach mask-wearing have improved participants' ability to wear a face mask. These findings suggest that even children who may have difficulty wearing a mask can do so effectively through targeted interventions.
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External links
- Filtering out confusion. Frequently Asked Questions about Respiratory Protection – National Institute for Occupational Safety and Health
- Juwarkar CS (September 2013). "Cleaning and sterilisation of anaesthetic equipment". Indian Journal of Anaesthesia. 57 (5): 541–550. PMID 24249888.
- Coronavirus disease (COVID-19) advice for the public: When and how to use masks