Comparison of the Filtration Efficiency of Different Face Masks Against Aerosols

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic can spread through virus-containing aerosols ( ≤ 5 μm) and larger airborne droplets. Quantifying filtration efficiency of different kinds of masks and linings for aerosols that fall within the most penetrating particle size (80-400 nm) is critical to limiting viral transmission. The objective of our experiment was to compare the “real-world” filtering efficiency of different face masks for fine aerosols (350 nm) in laboratory simulations.Methods: We performed a simulated bench test that measured the filtering efficiency of N95 vs. N99 masks with elastomeric lining in relation to baseline (“background”) aerosol generation. A mannequin head was placed within a chamber and was attached to an artificial lung simulator. Particles of known size (350 ± 6 nm aerodynamic diameter) were aerosolized into the chamber while simulating breathing at physiological settings of tidal volume, respiratory rate, and airflow. Particle counts were measured between the mannequin head and the lung simulator at the tracheal airway location.Results: Baseline particle counts without a filter (background) were 2,935 ± 555 (SD) cm−3, while the N95 (1348 ± 92 cm−3) and N99 mask with elastomeric lining (279 ± 164 cm−3; p <0.0001) exhibit lower counts due to filtration.Conclusion: The filtration efficiency of the N95 (54.1%) and N99 (90.5%) masks were lower than the filtration efficiency rating. N99 masks with elastomeric lining exhibit greater filtration efficiency than N95 masks without elastomeric lining and may be preferred to contain the spread of SARS-CoV-2 infection.

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Aerosol generation during surgical tracheostomy in a patient with COVID-19

Critical Care and Resuscitation ◽

10.51893/2020.4.rl2r ◽

2020 ◽

Vol 23 (4) ◽

pp. 391-393

Author(s):

Forbes McGain ◽

◽

Ruhi S Humphries ◽

Juan Carlos Mora ◽

Patrick Timms ◽

...

Keyword(s):

Health Care ◽

Severe Acute Respiratory Syndrome ◽

Health Care Workers ◽

Viral Transmission ◽

Surgical Tracheostomy ◽

Aerosol Generation ◽

Care Workers

Significant concern exists regarding the risk of transmission of severe acute respiratory syndrome coronavirus 2 (SARSCov-2) to health care workers during aerosol generating procedures.The risk of viral transmission to health care workers during tracheostomy insertion is unknown.

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SARS-CoV-2 aerosol generation during respiratory equipment reprocessing

Antimicrobial Resistance and Infection Control ◽

10.1186/s13756-021-00955-2 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Camila Quartim de Moraes Bruna ◽

Caroline Lopes Ciofi-Silva ◽

Anderson Vicente de Paula ◽

Lucy Santos Villas Boas ◽

Noely Evangelista Ferreira ◽

...

Keyword(s):

Intensive Care ◽

Severe Acute Respiratory Syndrome ◽

Intensive Care Units ◽

Medical Devices ◽

Aerosol Generation ◽

Surface Samples ◽

Tertiary Hospitals ◽

Air Sample ◽

Sterile Processing

AbstractAerosolization may occur during reprocessing of medical devices. With the current coronavirus disease 2019 pandemic, it is important to understand the necessity of using respirators in the cleaning area of the sterile processing department. To evaluate the presence of severe acute respiratory syndrome coronavirus (SARS-CoV-2) in the air of the sterile processing department during the reprocessing of contaminated medical devices. Air and surface samples were collected from the sterile processing department of two teaching tertiary hospitals during the reprocessing of respiratory equipment used in patients diagnosed with coronavirus disease 2019 and from intensive care units during treatment of these patients. SARS-CoV-2 was detected only in 1 air sample before the beginning of decontamination process. Viable severe acute respiratory syndrome coronavirus 2 RNA was not detected in any sample collected from around symptomatic patients or in sterile processing department samples. The cleaning of respiratory equipment does not cause aerosolization of SARS-CoV-2. We believe that the use of medical masks is sufficient while reprocessing medical devices during the coronavirus disease 2019 pandemic.

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Influence of particle size and operating parameters on virus ultrafiltration efficiency

Water Science & Technology Water Supply ◽

10.2166/ws.2011.005 ◽

2011 ◽

Vol 11 (1) ◽

pp. 31-38

Author(s):

Angayar K. Pavanasam ◽

Ali Abbas ◽

Vicki Chen

Keyword(s):

Particle Size ◽

Filtration Efficiency ◽

Transmembrane Pressure ◽

Operating Parameters ◽

Particle Removal ◽

Major Step ◽

Virus Removal ◽

Virus Particles ◽

Key Factor ◽

Effect Of Particle Size

In water treatment, virus removal using ultrafiltration is a major step towards better water quality. In this paper, we study virus filtration efficiency using surrogate virus particles and via statistical surface-response approach. We focus on the effect of particle size (20–100 nm range) as a key factor along with the effects of transmembrane pressure (20–60 kPa range) and feed flowrate (0.3–1.0 L/F;min range) on the filtration virus removal efficiency (LRV). The particle size is shown to impart a great deal of influence on surrogate particle removal. The effect of particle-to-pore-size ratio is reported for comparison of membrane molecular weight cut off (MWCO) performance. It was shown experimentally and through the developed empirical regression model that transmembrane pressure plays a major role in controlling the filtration efficiency along with flowrate. In the studied experimental range, higher LRV values are obtained at lower transmembrane pressure (20 kPa) and at higher feed flowrate (1 L/F;min). Further the effect on LRV of the interaction between transmembrane pressure and particle size seems to be more significant than that of the interaction of flowrate with particle size.

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Inward and outward effectiveness of cloth masks, a surgical mask, and a face shield

10.1101/2020.11.18.20233353 ◽

2020 ◽

Author(s):

Jin Pan ◽

Charbel Harb ◽

Weinan Leng ◽

Linsey C. Marr

Keyword(s):

Particle Size ◽

Respiratory Tract ◽

Filtration Efficiency ◽

The Other ◽

Woven Fabric ◽

Protection Efficiency ◽

Overall Efficiency

AbstractWe evaluated the effectiveness of 11 face coverings for material filtration efficiency, inward protection efficiency on a manikin, and outward protection efficiency on a manikin. At the most penetrating particle size, the vacuum bag, microfiber cloth, and surgical mask had material filtration efficiencies >50%, while the other materials had much lower filtration efficiencies. However, these efficiencies increased rapidly with particle size, and many materials had efficiencies >50% at 2 μm and >75% at 5 μm. The vacuum bag performed best, with efficiencies of 54-96% for all three metrics, depending on particle size. The thin acrylic and face shield performed worst. Inward protection efficiency and outward protection efficiency were similar for many masks; the two efficiencies diverged for stiffer materials and those worn more loosely (e.g., bandana) or more tightly (e.g., wrapped around the head) compared to a standard earloop mask. Discrepancies between material filtration efficiency and inward/outward protection efficiency indicated that the fit of the mask was important. We calculated that the particle size most likely to deposit in the respiratory tract when wearing a mask is ∼2 μm. Based on these findings, we recommend a three-layer mask consisting of outer layers of a flexible, tightly woven fabric and an inner layer consisting of a material designed to filter out particles. This combination should produce an overall efficiency of >70% at the most penetrating particle size and >90% for particles 1 μm and larger if the mask fits well.

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Why COVID-19 Transmission Is More Efficient and Aggressive Than Viral Transmission in Previous Coronavirus Epidemics?

Biomolecules ◽

10.3390/biom10091312 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1312 ◽

Cited By ~ 2

Author(s):

Fatma Elrashdy ◽

Elrashdy M. Redwan ◽

Vladimir N. Uversky

Keyword(s):

Middle East ◽

Environmental Factors ◽

Severe Acute Respiratory Syndrome ◽

Human Population ◽

Viral Transmission ◽

Host Factors ◽

The Past ◽

Viral Structure ◽

The World ◽

Human Host Factors

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing a pandemic of coronavirus disease 2019 (COVID-19). The worldwide transmission of COVID-19 from human to human is spreading like wildfire, affecting almost every country in the world. In the past 100 years, the globe did not face a microbial pandemic similar in scale to COVID-19. Taken together, both previous outbreaks of other members of the coronavirus family (severe acute respiratory syndrome (SARS-CoV) and middle east respiratory syndrome (MERS-CoV)) did not produce even 1% of the global harm already inflicted by COVID-19. There are also four other CoVs capable of infecting humans (HCoVs), which circulate continuously in the human population, but their phenotypes are generally mild, and these HCoVs received relatively little attention. These dramatic differences between infection with HCoVs, SARS-CoV, MERS-CoV, and SARS-CoV-2 raise many questions, such as: Why is COVID-19 transmitted so quickly? Is it due to some specific features of the viral structure? Are there some specific human (host) factors? Are there some environmental factors? The aim of this review is to collect and concisely summarize the possible and logical answers to these questions.

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Characterization of Airborne Particles Emitted During Application of Cosmetic Talc Products

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16203830 ◽

2019 ◽

Vol 16 (20) ◽

pp. 3830 ◽

Cited By ~ 2

Author(s):

Pat Rasmussen ◽

Christine Levesque ◽

Jianjun Niu ◽

Howard Gardner ◽

Gregory Nilsson ◽

...

Keyword(s):

Particle Size ◽

Consumer Products ◽

Airborne Particles ◽

Aerodynamic Diameter ◽

Breathing Zone ◽

Direct Reading ◽

Detailed Characterization ◽

Adult Body ◽

Reading Instruments

A pilot study was undertaken to characterize the concentration, duration and particle size distribution of the talc cloud that forms in the personal breathing zone (PBZ) during application of certain talc-containing cosmetics. Multiple direct-reading instruments were employed to simultaneously monitor PM4 concentrations (particulate matter with aerodynamic diameter < 4 µm; mg/m3) at different distances from each of three subjects while they applied talc products. Results indicated that the purpose and method of applying the talc product, combined with behavioral and physical differences amongst subjects, all strongly influenced airborne talc concentrations and the duration of the cloud. Air concentrations of talc in the PBZ averaged around 1.0 mg/m3, and the duration of exposure varied from less than one minute to more than ten minutes. The real-time monitors captured the occasional formation of secondary clouds, likely caused by resuspension of talc particles from skin or other surfaces. Measurements of aerosolized baby powder, face powder, and two adult body powders indicated that the median aerodynamic diameter of the talc cloud ranged from 1.7 to 2.0 µm. These direct-reading approaches were valuable for providing detailed characterization of short duration exposures to airborne talc particles, and will be useful to support future exposure assessments of talc and other powders in consumer products.

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Detection of Airborne Severe Acute Respiratory Syndrome (SARS) Coronavirus and Environmental Contamination in SARS Outbreak Units

The Journal of Infectious Diseases ◽

10.1086/429634 ◽

2005 ◽

Vol 191 (9) ◽

pp. 1472-1477 ◽

Cited By ~ 201

Author(s):

Timothy F. Booth ◽

Bill Kournikakis ◽

Nathalie Bastien ◽

Jim Ho ◽

Darwyn Kobasa ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Environmental Contamination ◽

Respiratory Protection ◽

Chain Reaction ◽

Air Samples ◽

Aerosol Generation ◽

Hygiene Practices ◽

Viral Aerosol ◽

Polymerase Chain ◽

Droplet Transmission

Abstract Severe acute respiratory syndrome (SARS) is characterized by a risk of nosocomial transmission; however, the risk of airborne transmission of SARS is unknown. During the Toronto outbreaks of SARS, we investigated environmental contamination in SARS units, by employing novel air sampling and conventional surface swabbing. Two polymerase chain reaction (PCR)–positive air samples were obtained from a room occupied by a patient with SARS, indicating the presence of the virus in the air of the room. In addition, several PCR-positive swab samples were recovered from frequently touched surfaces in rooms occupied by patients with SARS (a bed table and a television remote control) and in a nurses’ station used by staff (a medication refrigerator door). These data provide the first experimental confirmation of viral aerosol generation by a patient with SARS, indicating the possibility of airborne droplet transmission, which emphasizes the need for adequate respiratory protection, as well as for strict surface hygiene practices

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Estimates of the ongoing need for social distancing and control measures post-“lockdown” from trajectories of COVID-19 cases and mortality

European Respiratory Journal ◽

10.1183/13993003.01483-2020 ◽

2020 ◽

Vol 56 (1) ◽

pp. 2001483 ◽

Cited By ~ 6

Author(s):

Mike Lonergan ◽

James D. Chalmers

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Economic Activity ◽

Regression Models ◽

Reproduction Number ◽

Viral Transmission ◽

Control Measures ◽

Social Distancing ◽

And Control ◽

Doubling Times

By 21 May 2020, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) had caused more than 5 million cases of coronavirus 2019 (COVID-19) across more than 200 countries. Most countries with significant outbreaks have introduced social distancing or “lockdown” measures to reduce viral transmission. So the key question now is when, how and to what extent these measures can be lifted.Publicly available data on daily numbers of newly confirmed cases and mortality were used to fit regression models estimating trajectories, doubling times and the reproduction number (R0) of the disease, before and under the control measures. These data ran up to 21 May 2020, and were sufficient for analysis in 89 countries.The estimates of R0 before lockdown based on these data were broadly consistent with those previously published: between 2.0 and 3.7 in the countries with the largest number of cases available for analysis (USA, Italy, Spain, France and UK). There was little evidence to suggest that the restrictions had reduced R far below 1 in many places, with France having the most rapid reductions: R0 0.76 (95% CI 0.72–0.82) based on cases, and 0.77 (95% CI 0.73–0.80) based on mortality.Intermittent lockdown has been proposed as a means of controlling the outbreak while allowing periods of increased freedom and economic activity. These data suggest that few countries could have even 1 week per month unrestricted without seeing resurgence of the epidemic. Similarly, restoring 20% of the activity that has been prevented by the lockdowns looks difficult to reconcile with preventing the resurgence of the disease in most countries.

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Experimental Evaluation of Perfluorocarbon Aerosol Generation with Two Novel Nebulizer Prototypes

Pharmaceutics ◽

10.3390/pharmaceutics11010019 ◽

2019 ◽

Vol 11 (1) ◽

pp. 19 ◽

Cited By ~ 4

Author(s):

Iñigo Aramendia ◽

Unai Fernandez-Gamiz ◽

Alberto Lopez-Arraiza ◽

Carmen Rey-Santano ◽

Victoria Mielgo ◽

...

Keyword(s):

Circular Ring ◽

Geometric Standard Deviation ◽

Distilled Water ◽

Aerodynamic Diameter ◽

Mean Values ◽

Non Invasive ◽

Aerosol Generation ◽

Non Invasive Ventilation ◽

Particle Sizer ◽

Invasive Techniques

The potential of non-invasive ventilation procedures and new minimally invasive techniques has resulted in the research of alternative approaches as the aerosolization for the treatment of respiratory distress syndrome (RDS). The aim of this work was to design two nebulizer prototypes and to evaluate them studying the particle size distribution of the inhaled droplets generated with distilled water and two perfluorocarbons (PFCs). Different experiments were performed with driving pressures of 1–3 bar for each compound. An Aerodynamic Particle Sizer was used to measure the aerodynamic diameter (Da), the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD). The results showed that both prototypes produced heterodisperse aerosols with Da mean values in all cases below 5 µm. The initial experiments with distilled water showed MMAD values lower than 9 µm and up to 15 µm with prototype 1 and prototype 2, respectively. Regarding the PFCs, relatively uniform MMAD values close to 12 µm were achieved. The air delivery with outer lumens of prototype 1 presented more suitable mass distribution for the generation and delivery of a uniform aerosol than the two half-circular ring geometry proposed in the prototype 2.

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