Combined Effects of Masking and Distance on Aerosol Exposure Potential

Tomshine, Jonathan R.; Dennis, Kendall D.; Bruhnke, Russell E.; Christensen, James H.; Halvorsen, T.G.; Hogan, Christopher J.; O’Horo, John C.; Breeher, Laura E.; Callstrom, Matthew R.; Wehde, Mark

doi:10.1016/j.mayocp.2021.05.007

Cited by 13 publications

(22 citation statements)

References 28 publications

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“…No one strategy is sufficient to prevent transmission, and multiple interventions should be used concurrently to reduce the spread of disease ( 6 ). Proven effective strategies against SARS-CoV-2 transmission, beyond vaccination, include using masks consistently and correctly ( 7 , 8 ), maximizing ventilation both through dilution ( 9 , 10 ) and filtration ( 11 ) of air, and maintaining physical distance and avoiding crowds ( 12 , 13 ). Basic public health measures such as staying home when sick, handwashing, and regular cleaning of high-touch surfaces should also be encouraged.…”

mentioning

confidence: 99%

Guidance for Implementing COVID-19 Prevention Strategies in the Context of Varying Community Transmission Levels and Vaccination Coverage

Christie

Brooks

Hicks

et al. 2021

MMWR Morb. Mortal. Wkly. Rep.

134

111

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this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).COVID-19 vaccination remains the most effective means to achieve control of the pandemic. In the United States, COVID-19 cases and deaths have markedly declined since their peak in early January 2021, due in part to increased vaccination coverage (1). However, during June 19-July 23, 2021, COVID-19 cases increased approximately 300% nationally, followed by increases in hospitalizations and deaths, driven by the highly transmissible B.1.617.2 (Delta) variant* of SARS-CoV-2, the virus that causes COVID-19. Available data indicate that the vaccines authorized in the United States (Pfizer-BioNTech, Moderna, and Janssen [Johnson & Johnson]) offer high levels of protection against severe illness and death from infection with the Delta variant and other currently circulating variants of the virus (2). Despite widespread availability, vaccine uptake has slowed nationally with wide variation in coverage by state (range = 33.9%-67.2%) and by county (range = 8.8%-89.0%). † Unvaccinated persons, as well as persons with certain immunocompromising conditions (3), remain at substantial risk for infection, severe illness, and death, especially in areas where the level of SARS-CoV-2 community transmission is high. The Delta variant is more than two times as transmissible as the original strains circulating at the start of the pandemic and is causing large, rapid increases in infections, which could compromise the capacity of some local and regional health care systems to provide medical care for the communities they serve. Until vaccination coverage is high and community transmission is low, public health practitioners, as well as schools, businesses, and institutions (organizations) need to regularly assess the need for prevention strategies to avoid stressing health care capacity and imperiling adequate care for both COVID-19 and other non-COVID-19 conditions. CDC recommends five critical factors be considered to inform local decisionmaking: 1) level of SARS-CoV-2 community transmission; 2) health system capacity; 3) COVID-19 vaccination coverage; 4) capacity for early detection of increases in COVID-19 cases; * Point-in-time information is available from CDC COVID Data Tracker. https:// covid.cdc.gov/covid-data-tracker/#variant-proportions † Persons are considered fully vaccinated if ≥2 weeks have elapsed following receipt of the second dose in a 2-dose series of Moderna or Pfizer-BioNTech mRNA COVID-19 vaccine, or ≥2 weeks following receipt of 1-dose of Janssen (Johnson & Johnson) vaccine. Data are available from CDC COVID Data Tracker. https://covid.cdc.gov/covid-data-tracker

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mentioning

confidence: 99%

Guidance for Implementing COVID-19 Prevention Strategies in the Context of Varying Community Transmission Levels and Vaccination Coverage

Christie

Brooks

Hicks

et al. 2021

MMWR Morb. Mortal. Wkly. Rep.

134

111

View full text Add to dashboard Cite

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“…This was an a priori choice given the high number of studies that have been completed on mask effectiveness. 76 (5) We did not investigate the presence of other occupants within the classroom. This decision was also made a priori to concentrate fully on the impact of PAF units on localized and whole-room deposition and concentration within the classroom.…”

Section: Conclusion and Limitationsmentioning

confidence: 99%

Localized and Whole-Room Effects of Portable Air Filtration Units on Aerosol Particle Deposition and Concentration in a Classroom Environment

Kong

Eilts

et al. 2022

ACS EST Eng.

Self Cite

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In indoor environments with limited ventilation, recirculating portable air filtration (PAF) units may reduce COVID-19 infection risk via not only the direct aerosol route (i.e., inhalation) but also via an indirect aerosol route (i.e., contact with the surface where aerosol particles deposited). We systematically investigated the impact of PAF units in a mock classroom, as a supplement to background ventilation, on localized and whole-room surface deposition and particle concentration. Fluorescently tagged particles with a volumetric mean diameter near 2 μm were continuously introduced into the classroom environment via a breathing simulator with a prescribed inhalation–exhalation waveform. Deposition velocities were inferred on >50 horizontal and vertical surfaces throughout the classroom, while aerosol concentrations were spatially monitored via optical particle spectrometry. Results revealed a particle decay rate consistent with expectations based upon the reported clean air delivery rates of the PAF units. Additionally, the PAF units reduced peak concentrations by a factor of around 2.5 compared to the highest concentrations observed and led to a statistically significant reduction in deposition velocities for horizontal surfaces >2.5 m from the aerosol source. Our results not only confirm that PAF units can reduce particle concentrations but also demonstrate that they may lead to reduced particle deposition throughout an indoor environment when properly positioned with respect to the location of the particle source(s) within the room (e.g., where the largest group of students sit) and the predominant air distribution profile of the room.

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“…A 1-metre distance between students should be aimed for when distancing is required, provided students are masked. 22,113,115 If space in the classroom does not allow for adequate distancing, attention should be paid to other mitigation measures such as ventilation and filtration rather than a return to adaptive models.…”

Section: Physical Distancingmentioning

confidence: 99%

School Operation for the 2021-2022 Academic Year in the Context of the COVID-19 Pandemic

Science¹,

Thampi²,

Bitnun³

et al. 2021

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In-person learning is essential for the learning and overall well-being of children and youth. Therefore, barring catastrophic circumstances, schools should remain open for in-person learning.The level of community COVID-19 burden should inform the degree of school-based measures: the provided framework should be implemented at the regional level by public health units, considering local vaccination coverage rate and metrics of COVID-19 disease severity and to a lesser extent, SARS-CoV-2 transmission rate.Permanent measures that support the ongoing operation of schools, irrespective of the COVID-19 pandemic, include vaccination of all eligible individuals, exclusion of sick students and staff, hand hygiene, adequate ventilation, and environmental cleaning.Temporary measures (e.g., masking, physical distancing, cohorting) implemented in response to changes in COVID-19 disease burden should take into consideration student age, grade, and vaccination status.Re-initiation and maintenance of extracurricular activities (e.g., music, sports, clubs) is an important component of return-to-school plans.

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Combined Effects of Masking and Distance on Aerosol Exposure Potential

Cited by 13 publications

References 28 publications

Guidance for Implementing COVID-19 Prevention Strategies in the Context of Varying Community Transmission Levels and Vaccination Coverage

Guidance for Implementing COVID-19 Prevention Strategies in the Context of Varying Community Transmission Levels and Vaccination Coverage

Localized and Whole-Room Effects of Portable Air Filtration Units on Aerosol Particle Deposition and Concentration in a Classroom Environment

School Operation for the 2021-2022 Academic Year in the Context of the COVID-19 Pandemic

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