Efficacy of universal masking for source control and personal protection from simulated cough and exhaled aerosols in a room

Lindsley, William G.; Beezhold, Donald H.; Coyle, Jayme P.; Derk, Raymond C.; Blachère, Françoise M.; Boots, Theresa; Reynolds, Jeffrey; McKinney, Walter; Sinsel, Erik W.; Noti, John D.

doi:10.1080/15459624.2021.1939879

Cited by 21 publications

(39 citation statements)

References 42 publications

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“…In contrast to other studies, Lindsley and colleagues (2021), in addition to evaluating the masks in an automated system, also evaluated the fit of the ones to the face of individuals. Despite presenting similar results to the others, regarding filtering and blocking, it was observed that these factors can be affected when related the fit of the masks to the face of the individual is taken into consideration [ 31 ]. The hypothesis of facial fit and incorrect handling of the mask may possibly answer and be related to the fact that some masks (7/24, 29.1%) in our study presented positive inner sides.…”

Section: Discussionmentioning

confidence: 85%

Effectiveness of face masks in blocking the transmission of SARS-CoV-2: A preliminary evaluation of masks used by SARS-CoV-2-infected individuals

et al. 2022

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In 2019, a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is transmitted via the airborne route, caused a new pandemic namely, “coronavirus disease 2019” (COVID-19). Although the effectiveness of face masks to prevent the transmission of SARS-CoV-2 is debated, no study has evaluated the virus-blocking efficacy of masks used by patients. We aimed to evaluate this efficacy of masks used by SARS-CoV-2-infected individuals. Data, masks used, and nasopharyngeal swab samples were obtained from these patients. Forty-five paired samples of nasopharyngeal swabs and masks were obtained and processed; the majority of masks were woven. Viral RNAs were amplified using quantitative reverse‐transcription polymerase chain reaction and detected only on the inner parts of masks. Median viral load (VL) values of swabs and masks were 1.954x106 and 2,51x103, respectively. Statistically, there was a difference of approximately 1000 RNA copies/mL between swabs and masks and no significant difference in VL values among different types of masks. There were statistically significant differences in VL values between men and women and between symptomatic and asymptomatic patients. Our findings suggest the blocking of virus transmission by different types of masks and reinforce the use of masks by both infected and non-infected individuals.

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Section: Discussionmentioning

confidence: 85%

Effectiveness of face masks in blocking the transmission of SARS-CoV-2: A preliminary evaluation of masks used by SARS-CoV-2-infected individuals

et al. 2022

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“…Respiratory exposure studies were performed using a simulator that expels a test aerosol (the source) and a breathing simulator (the recipient) inside an experimental chamber as previously described. 9 , 18 Briefly, a medical face mask or cloth mask (with or without fit modification) was placed on the source simulator situated 6 feet from the recipient simulator. An optical particle counter (Grimm 1.108; Aerosol Technik Ainring GmbH & Co. KG; Ainring, Germany) was used to measure the aerosol concentration at the mouth of an unmasked recipient simulator.…”

Section: Methodsmentioning

confidence: 99%

Face mask fit modifications that improve source control performance

Blachère

Lemons

Coyle

et al. 2022

American Journal of Infection Control

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Background During the COVID-19 pandemic, face masks are used as source control devices to reduce the expulsion of respiratory aerosols from infected people. Modifications such as mask braces, earloop straps, knotting and tucking, and double masking have been proposed to improve mask fit however the data on source control are limited. Methods The effectiveness of mask fit modifications was determined by conducting fit tests on human subjects and simulator manikins and by performing simulated coughs and exhalations using a source control measurement system. Results Medical masks without modification blocked ≥56% of cough aerosols and ≥42% of exhaled aerosols. Modifying fit by crossing the earloops or placing a bracket under the mask did not increase performance, while using earloop toggles, an earloop strap, and knotting and tucking the mask increased performance. The most effective modifications for improving source control performance were double masking and using a mask brace. Placing a cloth mask over a medical mask blocked ≥85% of cough aerosols and ≥91% of exhaled aerosols. Placing a brace over a medical mask blocked ≥95% of cough aerosols and ≥99% of exhaled aerosols. Conclusions Fit modifications can greatly improve the performance of face masks as source control devices for respiratory aerosols.

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“…These findings suggest that portable HEPA air cleaners can reduce exposure to SARS-CoV-2 aerosols in indoor environments, with greater reductions in exposure occurring when used in combination with universal masking.A breathing aerosol source simulator was used to mimic a meeting participant exhaling infectious particles (source), and three breathing simulators were used to mimic a speaker and two participants exposed to these aerosol particles (receivers) (Figure 1). The methods used were similar to those used in previous studies of aerosol dispersion and transport in indoor spaces (3,4,6). The simulators were placed in a 584-ft 2 (54-m 2 ) * HEPA air cleaners consist of a filter capable of removing ≥99.97% of particles from the air and a fan or blower to draw air through the filter.…”

mentioning

confidence: 99%

Efficacy of Portable Air Cleaners and Masking for Reducing Indoor Exposure to Simulated Exhaled SARS-CoV-2 Aerosols — United States, 2021

Lindsley¹,

Derk²,

Coyle³

et al. 2021

MMWR Morb. Mortal. Wkly. Rep.

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Release on the MMWR website (https://www.cdc.gov/mmwr).SARS-CoV-2, the virus that causes COVID-19, can be spread by exposure to droplets and aerosols of respiratory fluids that are released by infected persons when they cough, sing, talk, or exhale. To reduce indoor transmission of SARS-CoV-2 between persons, CDC recommends measures including physical distancing, universal masking (the use of face masks in public places by everyone who is not fully vaccinated), and increased room ventilation (1). Ventilation systems can be supplemented with portable high efficiency particulate air (HEPA) cleaners* to reduce the number of infectious particles in the air and provide enhanced protection from transmission between persons (2); two recent reports found that HEPA air cleaners in classrooms could reduce overall aerosol particle concentrations by ≥80% within 30 minutes (3,4). To investigate the effectiveness of portable HEPA air cleaners and universal masking at reducing exposure to exhaled aerosol particles, the investigation team used respiratory simulators to mimic a person with COVID-19 and other, uninfected persons in a conference room. The addition of two HEPA air cleaners that met the Environmental Protection Agency (EPA)-recommended clean air delivery rate (CADR) (5) reduced overall exposure to simulated exhaled aerosol particles by up to 65% without universal masking. Without the HEPA air cleaners, universal masking reduced the combined mean aerosol concentration by 72%. The combination of the two HEPA air cleaners and universal masking reduced overall exposure by up to 90%. The HEPA air cleaners were most effective when they were close to the aerosol source. These findings suggest that portable HEPA air cleaners can reduce exposure to SARS-CoV-2 aerosols in indoor environments, with greater reductions in exposure occurring when used in combination with universal masking.A breathing aerosol source simulator was used to mimic a meeting participant exhaling infectious particles (source), and three breathing simulators were used to mimic a speaker and two participants exposed to these aerosol particles (receivers) (Figure 1). The methods used were similar to those used in previous studies of aerosol dispersion and transport in indoor spaces (3,4,6). The simulators were placed in a 584-ft 2 (54-m 2 ) * HEPA air cleaners consist of a filter capable of removing ≥99.97% of particles from the air and a fan or blower to draw air through the filter. HEPA air cleaners are commercially available, relatively inexpensive, and easy to use.

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Efficacy of universal masking for source control and personal protection from simulated cough and exhaled aerosols in a room

Abstract: doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

Cited by 21 publications

References 42 publications

Effectiveness of face masks in blocking the transmission of SARS-CoV-2: A preliminary evaluation of masks used by SARS-CoV-2-infected individuals

Effectiveness of face masks in blocking the transmission of SARS-CoV-2: A preliminary evaluation of masks used by SARS-CoV-2-infected individuals

Face mask fit modifications that improve source control performance

Efficacy of Portable Air Cleaners and Masking for Reducing Indoor Exposure to Simulated Exhaled SARS-CoV-2 Aerosols — United States, 2021

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