Surgical mask

A surgical mask, also known as a face mask, is intended to be worn by health professionals during healthcare procedures.[1][2] It is designed to prevent infections in patients and treating personnel by catching bacteria shed in liquid droplets and aerosols from the wearer's mouth and nose.[3][4][5] They are not designed to protect the wearer from breathing in airborne bacteria or viruses whose particles are smaller. With respect to some infections like influenza they appear as effective as respirators, such as N95 or FFP masks;[6] though the latter provide better protection in laboratory experiments due to their material, shape and tight seal.[7][8]

Surgical mask
A surgical mask
Other namesProcedure mask, medical mask, isolation mask, laser mask, fluid-resistant masks, face mask

Surgical masks vary by quality and levels of protection. Despite their name, not all surgical masks are appropriate to be used during surgery. Surgical masks may be labeled as surgical, isolation, dental, or medical procedure masks.[9] Chinese health officials distinguish between medical (non-surgical) and surgical masks.[10]

Surgical masks are made of a nonwoven fabric created using a melt blowing process. They came into use in the 1960s and largely replaced cloth facemasks in developed countries. The use of surgical masks during the COVID-19 pandemic has been a subject of debate,[11] as shortages of surgical masks is a central issue.[12][13] Surgical masks are popularly worn by the general public all year round in East Asian countries like China, Japan and South Korea to reduce the chance of spreading airborne diseases to others, and to prevent the breathing in of airborne dust particles created by air pollution.[14] Additionally, surgical masks have become a fashion statement, particularly in contemporary East Asian culture bolstered by its popularity in Japanese and Korean pop culture which have a big impact on East Asian youth culture.[15][16]

Usage

Health care workers
A medical professional wearing a surgical mask during an operation

A surgical mask is intended to be worn by health professionals during surgery and certain health care procedures[17] to catch microorganisms shed in liquid droplets and aerosols from the wearer's mouth and nose.[18]

Evidence supports the effectiveness of surgical masks in reducing the risk of infection among other healthcare workers and in the community.[19] 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.[20]

For healthcare workers, safety guidelines recommend the wearing of a face-fit tested N95 or FFP3 respirator mask instead of a surgical mask in the vicinity of pandemic-flu patients, to reduce the exposure of the wearer to potentially infectious aerosols and airborne liquid droplets.[21][22][23]

General public
People wearing surgical masks during the COVID-19 pandemic in Hong Kong.

In community and home settings, the use of facemasks and respirators generally are not recommended, with other measures preferred such as avoiding close contact and maintaining good hand hygiene.[18]

Surgical masks are popularly worn by the general public all year round in East Asian countries like China, Japan, South Korea and Taiwan to reduce the chance of spreading airborne diseases to others, and to prevent the breathing in of airborne dust particles created by air pollution.[14]

In Japan and Taiwan, it is common to see these masks worn during the flu season, as a show of consideration for others and social responsibility.[24][25][26] Surgical masks provide some protection against the spread of diseases, and improvised masks provide about half as much protection.[27]

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.[28][29][30] Additionally, face masks are used in Indonesia, Malaysia and Singapore during the Southeast Asian haze season.[31][32] 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.[33][34]

Additionally, surgical masks have become a fashion statement, particularly in contemporary East Asian culture bolstered by its popularity in Japanese and Korean pop culture which have a big impact on East Asian youth culture.[15][16]

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. In the 2019–20 Hong Kong protests, some protestors wore surgical masks amongst other types of mask to avoid recognition, and the government tried to ban such use.[35]

Function
Surgical masks retain some of the respiratory droplets released from the wearer through talking, coughing, or sneezing. Thus they reduce the spread of pathogens.[36]

A surgical mask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. If worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain viruses and bacteria, keeping it from reaching the wearer's mouth and nose.[38] Surgical masks are effective barriers for retaining large droplets released from the mouth and nose by the wearer in public.[36] Surgical masks help reduce exposure of the wearer's saliva and respiratory secretions to others[38] that could otherwise travel up to 26 feet.[39] Surgical mask also remind wearers not to touch their mouth or nose, which could otherwise transfer viruses and bacteria after having touched a contaminated surface.[37]

A surgical mask, by design, does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. Surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the face mask and the face.[38]

A surgical mask is not to be confused with a respirator and is not certified as such. Surgical masks are not designed to protect the wearer from inhaling airborne bacteria or virus particles and are less effective than respirators, which are designed for this purpose.[36] Collection efficiency of surgical mask filters can range from less than 10% to nearly 90% for different manufacturers’ masks when measured using the test parameters for NIOSH certification. However, a study found that even for surgical masks with "good" filters, 80–100% of subjects failed an OSHA-accepted qualitative fit test, and a quantitative test showed 12–25% leakage.[40]

Modern surgical masks are made from paper or other non-woven material and should be discarded after each use.[18]

Physical form

The design of the surgical masks depends on the mode; usually, the masks are three-ply (three layers). This three-ply material is made up of a melt-blown polymer, most commonly polypropylene, placed between non-woven fabric.[41] The melt-blown material acts as the filter that stops microbes from entering or exiting the mask.[41] Pleats are commonly used to allow the user to expand the mask such that it covers the area from the nose to the chin. The masks are secured to the head with ear loops, head ties, or elastic straps.[42]

Physical properties and quality
Physical properties of surgical masks
ParameterTypical unit
Pressure differential, ∆Pcm of H2O / cm²
Filtration and exposure%
Liquid penetration resistancembar
Air permeabilityml/s⋅cm² at 100 Pa
Water vapor permeabilityg/24 hr⋅cm²
Water repellencygrade

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),[43] liquid penetration resistance, air and water vapor permeability, water repellency (for outer and inner surfaces).[44]

Filtration and exposure is typically measured in bacterial filtration efficiency (BFE) and particulate filtration efficiency (PFE).[45]

History
Taiwan instituted a mask rationing system during the COVID-19 pandemic. With population of 24 million, Taiwan has been producing more than 13 million medical masks per day since March 2020.

Modern surgical masks began to be used in the 1960s. Their adoption caused cloth facemasks, which had been used since the late 19th century, to completely fall out of use in the developed world.[46][47] However, cloth masks and surgical masks both continued to be used in developing countries.[48]

COVID-19 pandemic

During the COVID-19 pandemic, some jurisdictions banned the practise of selling surgical masks to other nations due to a limited supply; however, Taiwan made refinements to those rules by permitting them to be mailed to first and second-degree relatives.[49]

Regulation
Single-use medical masks (YY/T 0969) produced by BYD Electronic.

In the United States, surgical masks are cleared for marketing by the U.S. Food and Drug Administration. As of 2009, manufacturers of surgical masks must demonstrate that their product is at least as good as a mask already on the market to obtain “clearance” for marketing. Manufacturers may choose from filter tests using a biological organism aerosol, or an aerosol of 0.1 µm latex spheres.[40]

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 ASTM F2100 and EN 14683 respectively. In both standards, a mask must have a Bacterial Filtration Efficiency (BFE) of more than 95%, simulated with particles of size 3.0 μm.[50]

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%).[45][51] Daily protective masks conforming to GB/T 32610 standard[52] is yet another type of masks that can have similar appearance to surgical masks.

See also

References
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  18. "Interim Recommendations for Facemask and Respirator Use to Reduce Novel Influenza A (H1N1) Virus Transmission". Centers for Disease Control and Prevention. May 27, 2009. Unless otherwise specified, the term "facemasks" refers to disposable facemasks cleared by the U.S. Food and Drug Administration (FDA) for use as medical devices. This includes facemasks labeled as surgical, dental, medical procedure, isolation, or laser masks... Facemasks should be used once and then thrown away in the trash.
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  20. Vincent, Marina; Edwards, Peggy (26 April 2016). "Disposable surgical face masks for preventing surgical wound infection in clean surgery" (PDF). Cochrane Database of Systematic Reviews. 4: CD002929. doi:10.1002/14651858.cd002929.pub3. PMC 7138271. PMID 27115326.
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  51. 中华人民共和国医药行业标准：YY/T 0969–2013 一次性使用医用口罩（Single-use medical face mask） (in Chinese)
  52. GB/T 32610–2016 Technical specification of daily protective mask
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