Source control (respiratory disease)

File:Droplet transmission ranges for speaking, intubation, and coughing or sneezing.jpg

Infections in general may spread by direct contact (for example, shaking hands or kissing), by inhaling infectious droplets in the air (droplet transmission), by inhaling long-lasting aerosols with tiny particles (airborne transmission), and by touching objects with infectious material on their surfaces (fomites). Different diseases spread in different ways; some spread by only some of these routes. For instance, fomite transmission of COVID-19 is thought to be rare while aerosol, droplet and contact transmission appear to be the primary transmission modes, {{as of|lc=yes|April 2021}}.{{cite journal | vauthors = Carbone M, Lednicky J, Xiao SY, Venditti M, Bucci E | title = Coronavirus 2019 Infectious Disease Epidemic: Where We Are, What Can Be Done and Hope For | journal = Journal of Thoracic Oncology | volume = 16 | issue = 4 | pages = 546–571 | date = April 2021 | pmid = 33422679 | pmc = 7832772 | doi = 10.1016/j.jtho.2020.12.014 }}

Coughs and sneezes can spread airborne droplets up to ~{{convert|8|meters|feet}}. Speaking can spread droplets up to ~{{convert|2|meters|feet}}.{{cite journal | vauthors = Sommerstein R, Fux CA, Vuichard-Gysin D, Abbas M, Marschall J, Balmelli C, Troillet N, Harbarth S, Schlegel M, Widmer A | title = Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19 | journal = Antimicrobial Resistance and Infection Control | volume = 9 | issue = 1 | pages = 100 | date = July 2020 | pmid = 32631450 | pmc = 7336106 | doi = 10.1186/s13756-020-00763-0 | doi-access = free }}

Masking any person who may be a source of infectious droplets (or aerosols) thus reduces the unsafe range of physical distances. If a person can be infectious before they are symptomatic and diagnosed, then people who do not yet know if they are infectious may also be a source of infection.

For pathogens transmitted through the air, strategies to block cough air jets and to capture aerosols, e.g. the "Shield & Sink" approach, can be highly effective in minimizing exposure to respiratory secretions.{{Cite medRxiv | vauthors = Hunziker P |date=2020-12-16 |title=Minimizing exposure to respiratory droplets, 'jet riders' and aerosols in air-conditioned hospital rooms by a 'Shield-and-Sink' strategy |language=en |medrxiv=10.1101/2020.12.08.20233056v1}}

Outside of respiratory source control, handwashing helps to protect people against contact transmission, and against indirect droplet transmission. Handwashing removes infectious droplets that their mask caught (from either side) and which transferred to their hands when they touched their mask.

In the past, suggestions have been made that covering the mouth and nose, like with an elbow, tissue, or hand, would be a viable measure towards reducing the transmissions of airborne diseases. This method of source control was suggested, but not empirically tested, in the "Control of Airborne Infection" section of a 1974 publication of Riley's Airborne Infection.{{cite journal | url=https://doi.org/10.1016/0002-9343(74)90140-5 | doi=10.1016/0002-9343(74)90140-5 | title=Airborne infection | date=1974 | journal=The American Journal of Medicine | volume=57 | issue=3 | pages=466–475 | pmid=4212915 | vauthors = Riley RL }} NIOSH also noted that the use of a tissue as source control, in their guidelines for TB, had not been tested as of 1992.{{Cite book |url=https://books.google.com/books?id=UJ78QaLuSxIC |title=NIOSH Recommended Guidelines for Personal Respiratory Protection of Workers in Health-care Facilities Potentially Exposed to Tuberculosis|date=1992|publisher=U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health|page=12}}

In 2013, Gustavo et al. looked into the effectiveness of various methods of source control, including via the arm, via a tissue, via bare hands, and via a surgical mask. They concluded that simply covering a cough was not an effective method of stopping transmission, and a surgical mask was not effective at reducing the amount of displaced droplets detected compared to the other rudimentary forms of source control.{{cite journal | doi=10.1186/1471-2458-13-811 | doi-access=free | title=Effectiveness of cough etiquette maneuvers in disrupting the chain of transmission of infectious respiratory diseases | date=2013 | journal=BMC Public Health | volume=13 | page=811 | pmid=24010919 | pmc=3846148 | vauthors = Zayas G, Chiang MC, Wong E, MacDonald F, Lange CF, Senthilselvan A, King M }} Another paper noted that the fit of a face mask matters in its source control performance.{{cite journal | url=https://doi.org/10.1080/02786826.2021.1933377 | doi=10.1080/02786826.2021.1933377 | title=A comparison of performance metrics for cloth masks as source control devices for simulated cough and exhalation aerosols | date=2021 | journal=Aerosol Science and Technology | volume=55 | issue=10 | pages=1125–1142 | pmid=35923216 | pmc=9345405 | bibcode=2021AerST..55.1125L | vauthors = Lindsley WG, Blachere FM, Beezhold DH, Law BF, Derk RC, Hettick JM, Woodfork K, Goldsmith WT, Harris JR, Duling MG, Boutin B, Nurkiewicz T, Boots T, Coyle J, Noti JD }} (However, note that OSHA 29 CFR 1910.134 does not cover the fit of face masks other than NIOSH-approved respirators.{{cite web|url=https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134|title=1910.134 - Respiratory Protection|publisher=OSHA|access-date=2024-07-18}})

== Contrast with personal protective equipment ==

File:Atemluftfilter Einwegmaske.jpg

While source control protects others from transmission arising from the wearer, personal protective equipment protects the wearer themselves.{{Cite web|title=Meat and Poultry Processing Workers and Employers: Interim Guidance from CDC and the Occupational Safety and Health Administration (OSHA)|url=https://www.cdc.gov/coronavirus/2019-ncov/community/organizations/meat-poultry-processing-workers-employers.html|date=2020-05-12|website=Centers for Disease Control and Prevention|at=At section "Cloth face coverings in meat and poultry processing facilities"|language=en-us|access-date=2020-05-24}} Cloth face masks can be used for source control (as a last resort) but are not considered personal protective equipment{{Cite web|title=FAQs on the Emergency Use Authorization for Face Masks (Non-Surgical)|url=https://www.fda.gov/medical-devices/emergency-situations-medical-devices/faqs-emergency-use-authorization-face-masks-non-surgical|date=2020-04-26|website=U.S. Food and Drug Administration|language=en|access-date=2020-05-21}} as they have low filter efficiency (generally varying between 2–60%), although they are easy to obtain and reusable after washing.{{cite journal | vauthors = Rengasamy S, Eimer B, Shaffer RE | title = Simple respiratory protection--evaluation of the filtration performance of cloth masks and common fabric materials against 20-1000 nm size particles | journal = The Annals of Occupational Hygiene | volume = 54 | issue = 7 | pages = 789–798 | date = October 2010 | pmid = 20584862 | pmc = 7314261 | doi = 10.1093/annhyg/meq044 | publisher = Oxford University Press | quote = The results showed that cloth masks and other fabric materials tested in the study had 40–90% instantaneous penetration levels against polydisperse NaCl aerosols employed in the National Institute for Occupational Safety and Health particulate respirator test protocol at 5.5 cm s⁻¹. | doi-access = free }} There are no standards or regulation for self-made cloth face masks,{{cite web|url=https://www.cdc.gov/niosh/topics/publicppe/community-ppe.html|title=Community Respirators and Masks|date=21 June 2023 |publisher=NIOSH|access-date=2024-06-22}} and source control on a well-fitted cloth mask is worse than a surgical mask.{{cite journal | title=Outward and inward protection efficiencies of different mask designs for different respiratory activities | date= February 2022 | vauthors = Koh XQ, Sng A, Chee JY, Sadovoy A, Luo P, Daniel D | journal=Journal of Aerosol Science | volume=160 | bibcode=2022JAerS.16005905K | doi=10.1016/j.jaerosci.2021.105905 }}

Surgical masks are designed to protect against splashes and sprays,{{Cite web|title=Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in Healthcare Settings|url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html|date=2020-05-18|website=U.S. Centers for Disease Control and Prevention|language=en-us|access-date=2020-05-21}} but do not provide complete respiratory protection from germs and other contaminants because of the loose fit between the surface of the face mask and the face.{{Cite web|title=N95 Respirators and Surgical Masks (Face Masks)|url=http://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-and-surgical-masks-face-masks|date=2020-04-05|website=U.S. Food and Drug Administration|language=en|access-date=2020-05-23}} Surgical masks are regulated by various national standards to have high bacterial filtration efficiency (BFE).{{cite web |title=Comparison of Mask Standards, Ratings, and Filtration Effectiveness|url=https://smartairfilters.com/en/blog/comparison-mask-standards-rating-effectiveness/| vauthors = Robertson P |date=15 March 2020|website=Smart Air Filters}}[https://max.book118.com/html/2020/0409/8133012113002105.shtm 中华人民共和国医药行业标准：YY 0469–2011 医用外科口罩 (Surgical mask)] (in Chinese)[https://max.book118.com/html/2018/0406/160266636.shtm 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)] {{Webarchive|url=https://web.archive.org/web/20210225125421/https://max.book118.com/html/2018/0406/160266636.shtm |date=2021-02-25 }} (in Chinese) N95/N99/N100 masks and other filtering facepiece respirators can provide source control in addition to respiratory protection, but respirators with an unfiltered exhalation valve may not provide source control and require additional measures to filter exhalation air when source control is required.

=== Exhalation source control with respirators ===

File:TB Respiratory Protection - Administrators Review.webm detailing the use of various types of respirators for the prevention of TB{{break}}(Script on Wikisource)]]

Some masks have exhalation valve that let the exhaled air go out unfiltered. The certification grade of the mask (such as N95) is about the mask itself and it does not warrant any safety about the air that is expelled by the wearer through the valve. A mask with valve mainly increases the comfort of the wearer.

Unfiltered exhalation of air is found on both filtering facepiece and elastomeric respirators with exhalation valves.{{cite web |title=Coronavirus Disease 2019 (COVID-19) |url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/elastomeric-respirators-strategy/index.html |website=Centers for Disease Control and Prevention |language=en-us |date=11 February 2020|archive-url=https://web.archive.org/web/20200505142849/https://www.cdc.gov/coronavirus/2019-ncov/hcp/elastomeric-respirators-strategy/index.html|archive-date=2020-05-05}} Unfiltered air is also found on powered air-purifying respirators, which cannot ever filter exhaled air.{{Cite book |last=Institute of Medicine |title=The Use and Effectiveness of Powered Air Purifying Respirators in Health Care: Workshop Summary |date=2015 |publisher=National Academies Press |isbn=978-0-309-31595-1 |location=Washington, D.C. |chapter=Defining PAPRs and Current Standards |doi=10.17226/18990 |pmid=25996018 |author-link=National Academy of Medicine |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK294223/}} During the COVID-19 pandemic, masks with unfiltered-exhalation valves ran counter to the requirements of some mandatory mask orders.{{cite news |last1=Wilson |first1=Mark |date=April 28, 2020 |title=What is a mask valve, and why are cities banning them? |work=MSN |url=https://www.msn.com/en-us/health/medical/what-is-a-mask-valve-and-why-are-cities-banning-them/ar-BB13jGNN}}{{cite news |last1=Webeck |first1=Evan |date=22 April 2020 |title=Coronavirus: Bay Area mask order takes effect Wednesday. Here's what you need to know. |work=The Mercury News |url=https://www.mercurynews.com/2020/04/22/coronavirus-bay-area-mask-order-takes-effect-wednesday-heres-what-you-need-to-know/}} Despite the aforementioned belief, a 2020 research by the NIOSH and CDC shows that an uncovered exhalation valve already provides source control on a level similar to, or even better than, surgical masks.{{Cite journal |vauthors=Portnoff L, Schall J, Brannen J, Suhon N, Strickland K, Meyers J |date=2020 |title=Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control |url=https://www.cdc.gov/niosh/docs/2021-107/default.html |journal=DHHS (NIOSH) Publication No. 2021-107 |language=en-us |publisher=National Institute for Occupational Safety and Health |doi=10.26616/NIOSHPUB2021107|doi-access=free }}

It is possible to seal some unfiltered exhalation valves{{cite tech report |date=30 June 2021 |title=Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control |url=https://www.cdc.gov/niosh/docs/2021-107/default.html |language=en-us |doi=10.26616/NIOSHPUB2021107 |s2cid=235456824 |doi-access=free}} or to cover it with an additional surgical mask; this might be done where mask shortages make it necessary.{{cite journal |last1=Liu |first1=DCY |last2=Koo |first2=TH |last3=Wong |first3=JKK |last4=Wong |first4=YH |last5=Fung |first5=KSC |last6=Chan |first6=Y |last7=Lim |first7=HS |date=August 2020 |title=Adapting re-usable elastomeric respirators to utilise anaesthesia circuit filters using a 3D-printed adaptor - a potential alternative to address N95 shortages during the COVID-19 pandemic. |journal=Anaesthesia |volume=75 |issue=8 |pages=1022–1027 |doi=10.1111/anae.15108 |pmc=7267584 |pmid=32348561 |doi-access=free}}{{cite web |title=San Antonio hospital could have an answer to the PPE crisis-- elastomeric masks |url=https://www.kens5.com/article/news/health/san-antonio-hospital-could-have-an-answer-to-the-ppe-crisis-elastomeric-masks/273-882e7ea3-e377-4776-906c-33ce89e193cc |website=kens5.com |date=May 1, 2020|quote=But she added you can easily cover the mask with a surgical mask or shield.}} However, so long as there are no shortages, respirators without exhalation valves should still be preferred in situations where source control is necessary.

{{clear}}

{{Globalize|section|date=June 2024}}

{{see also|N95 respirator#History|Hierarchy of hazard controls}}

File:N95 stop.svg administrative rule: No Admittance Without Wearing a Type N95 or More Protective Respirator{{cite web|url=https://www.osha.gov/laws-regs/federalregister/1997-10-17|title=DEPARTMENT OF LABOR Occupational Safety and Health Administration 29 CFR Part 1910 [Docket No. H-371] RIN 1218-AB46 Occupational Exposure to Tuberculosis}}]]

File:NIOSH’s “Hierarchy of Controls infographic” as SVG.svg's Hierarchy of Hazard Controls, multiple controls are used for source control of TB]]

File:Niosh tb guidelines.pdf under the old 30 CFR 11, replaced in 1995 (On Wikisource)]]

HIV was a noted co-infection in around 35% of those affected by TB in some regions of the US,{{cite book|title=Tuberculosis in the Workplace.|chapter=Introduction |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK222466/|publisher=National Academies Press (US)|date=2001}} despite extended close contact being a requisite factor for infection. Respirable particles are noted to be created by handling TB-infected tissue, or by coughing by those actively infected. Once in the air, droplet nuclei can persist in unventilated spaces. Most people infected with TB are asymptomatic, unless the immune system is weakened by some other factor, like HIV/AIDS, which can turn an infected person's latent TB into active TB source.{{cite book|title=Tuberculosis in the Workplace.|chapter=Basics of Tuberculosis. |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK222453/|publisher=National Academies Press (US)|date=2001}}

1994 CDC guidelines brought three methods of source control for the prevention of TB: administrative controls, engineering controls, and personal protective equipment, particularly with the use of fit-checked respirators.{{cite book|title=Tuberculosis in the Workplace.|chapter=Comparison of CDC Guidelines and Proposed OSHA Rule |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK222454/|publisher=National Academies Press (US)|date=2001}}

Administrative controls mainly involve people and areas in hospital responsible for TB controls, including training, skin-testing, and regulatory compliance, as well as those responsible for quantifying the amount of TB present in the hospital's community and in-hospital, like staff. To assist with this, OSHA proposed TB guidelines in 1997, but withdrew them in 2003 following the decline of TB.{{cite web|url=https://www.osha.gov/laws-regs/federalregister/2003-12-31-0|title=Part III DEPARTMENT OF LABOR Occupational Safety and Health Administration 29 CFR Part 1910 [Docket No. H-371] RIN 1218-AB46 Occupational Exposure to Tuberculosis}}

Engineering controls mainly involve ventilation and planning isolation rooms, but can also involve environmental controls, like negative pressure, ultraviolet germicidal radiation, and the use of HEPA filters.{{cite journal | vauthors = Lee JY | title = Tuberculosis Infection Control in Health-Care Facilities: Environmental Control and Personal Protection | journal = Tuberculosis and Respiratory Diseases | volume = 79 | issue = 4 | pages = 234–240 | date = October 2016 | pmid = 27790274 | pmc = 5077726 | doi = 10.4046/trd.2016.79.4.234 }}

The use of personal protective equipment, in this system of TB controls, requires the use of respirators whenever personnel are in contact with someone suspected of having TB, including during transport. This includes anyone near the infected person, all of whom must be provided with some sort of personal protective equipment, to avoid contracting TB. If PPE cannot be provided in time, the infected patient should be delayed from being moved through an area not controlled by PPE until the controls are in place, unless the care of the infected patient is compromised by an administrative delay.

During TB outbreaks in the 1990s, multiple hospitals upgraded their controls and policies to attenuate the spread of TB.{{cite book|title=Tuberculosis in the Workplace.|chapter=Implementation and Effects of CDC Guidelines |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK222468/|publisher=National Academies Press (US)|date=2001}}

File:2007 Guidelines for Isolation Precautions.pdf procedures. (PDF, 225 pages)]]

==== Pre-COVID ====

In 2007, the CDC HICPAC published a set of guidelines, called the 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings, suggesting that use of "barrier precautions", defined as "masks, gowns, [and] gloves", would not be required, so long as it was limited to "routine entry", patients were not confirmed to be infected, and no aerosol-generating procedures were being done. "Standard precautions" requiring the use of masks, face shields, and/or eye protection, would be needed if there was potential for the spraying of bodily fluids, like during intubation.{{cite web|url=https://www.osha.gov/Publications/OSHA3767.pdf|archive-url=https://web.archive.org/web/20180428195345/https://www.osha.gov/Publications/OSHA3767.pdf|date=May 2015|archive-date=2018-04-28|title=Hospital Respiratory Protection Program Toolkit|publisher=OSHA}}

The guidelines are the same regardless of the type of pathogen, but the guidelines also note that, based on the experience of SARS-CoV in Toronto, that "N95 or higher respirators may offer additional protection to those exposed to aerosol-generating procedures and high risk activities".

Separate from "barrier precautions" and "standard precautions" are "airborne precautions", a protocol for "infectious agents transmitted by the airborne route", like with SARS-CoV and tuberculosis, requiring 12 air changes per hour for new facilities, and use of fitted N95 respirators. These measures are used whenever someone is suspected of harboring an "infectious agent".{{cite web|url=https://stacks.cdc.gov/view/cdc/6878/cdc_6878_DS1.pdf|title=2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings}}

During the COVID-19 pandemic, cloth face masks for source control had been recommended by the U.S. Centers for Disease Control and Prevention (CDC) for members of the public who left their homes, and health care facilities were recommended to consider requiring face masks for all people who enter a facility. Health care personnel and patients with COVID-19 symptoms were recommended to use surgical masks if available, as they are more protective.{{Cite web|title=Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in Healthcare Settings|url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html|date=2020-05-18|website=U.S. Centers for Disease Control and Prevention|language=en-us|access-date=2020-05-21}} Masking patients reduces the personal protective equipment recommended by CDC for health care personnel under crisis shortage conditions.{{Cite web|title=Strategies for Optimizing the Supply of N95 Respirators|url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirators-strategy/index.html|date=2020-04-02|website=U.S. Centers for Disease Control and Prevention|at=At section "Prioritize the use of N95 respirators and facemasks by activity type"|language=en-us|access-date=2020-05-21}}

==== Post-2023 ====

By 2023, The New York Times noted that the CDC had dropped mandates for masks in hospitals during COVID, limiting the COVID policies to an advisory role. Use of masks for source control is still recommended in times of high viral activity, but the CDC did not provide numbers for benchmarks. The new policies are thought, according to the New York Times, based on various citations to medical literature, to increase mortality among vulnerable patients, especially those with cancer.{{cite web |url=https://www.nytimes.com/2023/09/23/health/hospitals-masking-mandates.html|work=New York Times|date=2023-09-23|access-date=2024-06-27| vauthors = Mandavilli A |title=In Hospitals, Viruses Are Everywhere. Masks Are Not.}}

The New York Times article cites a paper published in 2023, that suggests the high mortality of cancer patients following the Omicron wave may have been due to relaxing of policies preventing COVID-19 transmission{{cite journal | vauthors = Potter AL, Vaddaraju V, Venkateswaran S, Mansur A, Bajaj SS, Kiang MV, Jena AB, Yang CJ | title = Deaths Due to COVID-19 in Patients With Cancer During Different Waves of the Pandemic in the US | journal = JAMA Oncology | volume = 9 | issue = 10 | pages = 1417–1422 | date = October 2023 | pmid = 37651113 | doi = 10.1001/jamaoncol.2023.3066 }} (like source control policies). The 2023 paper also cites a research letter published in 2022, that suggests that the surge of COVID-19 cases in hospitals may have been due to the high contagiousness of Omicron,{{cite journal | vauthors = Klompas M, Pandolfi MC, Nisar AB, Baker MA, Rhee C | title = Association of Omicron vs Wild-type SARS-CoV-2 Variants With Hospital-Onset SARS-CoV-2 Infections in a US Regional Hospital System | journal = Jama | volume = 328 | issue = 3 | pages = 296–298 | date = July 2022 | pmid = 35704347 | pmc = 9201738 | doi = 10.1001/jama.2022.9609 }} an article which suggested a high secondary attack rate relative to Delta,{{cite journal | vauthors = Lyngse FP, Mortensen LH, Denwood MJ, Christiansen LE, Møller CH, Skov RL, Spiess K, Fomsgaard A, Lassaunière R, Rasmussen M, Stegger M, Nielsen C, Sieber RN, Cohen AS, Møller FT, Overvad M, Mølbak K, Krause TG, Kirkeby CT | title = Household transmission of the SARS-CoV-2 Omicron variant in Denmark | journal = Nature Communications | volume = 13 | issue = 1 | pages = 5573 | date = September 2022 | pmid = 36151099 | doi = 10.1038/s41467-022-33328-3 | bibcode = 2022NatCo..13.5573L }} and papers finding increased mortality of cancer patients due to higher rates of breakthrough infections.{{cite journal | vauthors = Gong IY, Vijenthira A, Powis M, Calzavara A, Patrikar A, Sutradhar R, Hicks LK, Wilton D, Singh S, Krzyzanowska MK, Cheung MC | title = Association of COVID-19 Vaccination With Breakthrough Infections and Complications in Patients With Cancer | journal = JAMA Oncology | volume = 9 | issue = 3 | pages = 386–394 | date = March 2023 | pmid = 36580318 | pmc = 10020872 | doi = 10.1001/jamaoncol.2022.6815 }}{{cite journal | vauthors = Potter AL, Vaddaraju V, Venkateswaran S, Mansur A, Bajaj SS, Kiang MV, Jena AB, Yang CJ | title = Deaths Due to COVID-19 in Patients With Cancer During Different Waves of the Pandemic in the US | journal = JAMA Oncology | volume = 9 | issue = 10 | pages = 1417–1422 | date = October 2023 | pmid = 37651113 | doi = 10.1001/jamaoncol.2023.3066 }}

Also in 2023, new draft guidelines were proposed by the CDC HICPAC, to update the pre-COVID 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings.{{efn|See Source control (respiratory disease)#Pre-COVID}} The proposed updates were met with disapproval by the National Nurses United union, as they felt the changes did not go far enough. Changes included clarifying by adding "source control" as a qualification for the use of "barrier precautions".{{cite web|url=https://www.cdc.gov/hicpac/pdf/2023-June-PE-508.pdf|title=Proposed Update to Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings (2007), 'Protective Environment' Recommendation|url-status=dead|archive-url=https://web.archive.org/web/20230822230457/https://www.cdc.gov/hicpac/pdf/2023-June-PE-508.pdf|archive-date=2023-08-22}}

A paper in the Journal of Hospital Infection, published in 2024, focusing on hospitals in the UK, found that the removal of mandates, based around surgical masks, in hospitals was not associated with an increase in SARS-CoV-2 infections from weeks between December 4, 2021 to December 10, 2022. However, the authors noted that the end of mask mandates also coincided with an increase in Omicron infections, and that more data would be needed despite evidence for removal of mask mandates from 2022-2023.{{cite journal | url=https://doi.org/10.1016/j.jhin.2023.12.004 | doi=10.1016/j.jhin.2023.12.004 | title=Impact of removing the healthcare mask mandate on hospital-acquired COVID-19 rates | date=2024 | journal=Journal of Hospital Infection | volume=145 | pages=59–64 | pmid=38141666 | vauthors = Mehra R, Patterson B, Riley P, Planche T, Breathnach A }}

• Face masks during the COVID-19 pandemic
• N95 respirator
• Respirator assigned protection factors
• Permissible exposure limit
• Workplace hazard controls for COVID-19

{{notelist}}

{{Reflist}}

{{Wikisource-multi|NIOSH Recommended Guidelines for Personal Respiratory Protection of Workers in Health-Care Facilities Potentially Exposed to Tuberculosis|NIOSH Change Will Save Health Care Industry Millions|t1=NIOSH TB guide}}

{{refbegin}}

• {{cite journal | url=https://doi.org/10.1016/S0196-6553(05)80143-9 | doi=10.1016/S0196-6553(05)80143-9 | title=Aerosol penetration through surgical masks | date=1992 | last1=Chen | first1=Chih-Chieh | last2=Willeke | first2=Klaus | journal=American Journal of Infection Control | volume=20 | issue=4 | pages=177–184 | pmid=1524265 }}
• {{cite journal | url=https://doi.org/10.1080/00028899908984440 | doi=10.1080/00028899908984440 | title=Compliance with OSHA's Respiratory Protection Standard in Hospitals | date=1999 | last1=Krishnan | first1=Usha | last2=Janicak | first2=Christopher A. | journal=American Industrial Hygiene Association Journal | volume=60 | issue=2 | pages=228–234 | pmid=10222573 }}

{{refend}}

{{Concepts in infectious disease}}

{{Occupational safety and health}}

Category:Respiratory diseases

Category:Occupational safety and health