scholarly journals A highly efficient cloth facemask

2021 ◽  
Author(s):  
Christopher Cappa ◽  
The San Francisco Opera Costume Department ◽  
William Ristenpart ◽  
Santiago Barreda ◽  
Nicole Bouvier ◽  
...  
Keyword(s):  
High Efficiency ◽  
Separation Distance ◽  
Filtration Efficiency ◽  
Ambient Aerosols ◽  
The Public ◽  
Professional Singers ◽  
Surgical Masks ◽  
Mask Design ◽  
N95 Respirators ◽  
Better Than

Abstract Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with less consideration given to mask design and shape. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency towards expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity and expansion of the breath-mask contact area. We further assess the performance of a new reusable cloth facemask design, originally made for, but not exclusive to, professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols >0.5 microns in diameter from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. Air exchange between the mask deadspace and the ambient environment limits the extent of CO2 buildup and in inhaled air and maintains O2 levels near ambient. The mask design also provides for less inhibited mouth and jaw movement and lower relative humidity, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.

scholarly journals An improved and highly efficient geometry for facemasks

2021 ◽  
Author(s):  
Christopher Cappa ◽  
William Ristenpart ◽  
Santiago Barreda ◽  
Nicole Bouvier ◽  
Anthony Wexler ◽  
...  
Keyword(s):  
High Efficiency ◽  
Separation Distance ◽  
Filtration Efficiency ◽  
Ambient Aerosols ◽  
The Public ◽  
Professional Singers ◽  
Surgical Masks ◽  
Mask Design ◽  
N95 Respirators ◽  
Better Than

Abstract Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with little consideration given to mask geometry. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency towards expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity. We further assess the performance of a new reusable cloth facemask design, originally made for professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. The mask design also provides for less inhibited mouth and jaw movement, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.

scholarly journals An improved and highly efficient geometry for facemasks

2021 ◽  
Author(s):  
Christopher Cappa ◽  
William Ristenpart ◽  
Santiago Barreda ◽  
Nicole Bouvier ◽  
Anthony Wexler ◽  
...  
Keyword(s):  
Respiratory Diseases ◽  
High Efficiency ◽  
Ambient Aerosols ◽  
The Public ◽  
Professional Singers ◽  
Surgical Masks ◽  
Mask Design ◽  
Different Populations ◽  
N95 Respirators ◽  
Better Than

Abstract Wearing masks and face coverings helps reduce transmission of respiratory diseases. Various mask designs exist that target different populations, occupations, and environments. Here, we present evidence that a new facemask design, originally made for professional singers, offers advantages that will strongly benefit the public. Specifically, we show that with proper fitting the reusable cloth singing mask achieves overall filtering efficiencies for both exhaled expiratory aerosols and for inhaled ambient aerosols of >93%, better than surgical masks and approaching N95 respirators. We attribute the high efficiency largely to the mask design, rather than material. The mask design also provides for less inhibited mouth and jaw movement and overall lower humidity within the mask, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.

scholarly journals Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency

2020 ◽  
Author(s):  
Amy Mueller ◽  
Loretta Fernandez
Keyword(s):  
Health Care Providers ◽  
Ambient Air ◽  
Filtration Efficiency ◽  
Airborne Particles ◽  
Particle Removal ◽  
Breathing Zone ◽  
Care Providers ◽  
Particle Filtration ◽  
Surgical Masks ◽  
Mask Design

AbstractIn response to the critical shortage of medical masks resulting from the COVID-19 pandemic, large portions of the population are mobilizing to produce cloth masks using locally-sourced fabrics, however the efficacy of these masks as a means of protecting the wearer from airborne particles carrying virus is not well known. Further, existing protocols are designed for testing the fit and performance N95 respirators and tight-fitting facemasks rather than the relatively more loose-fitting surgical mask style most cloth masks follow. In this study tools and methods typically used to assess tight-fitting facemasks were modified to assess the efficacy of community-produced fabric and commercially-produced surgical masks in terms of protecting the wearer from airborne particles that may be carrying virus. Two TSI PortaCount (model 8028) instruments were operated concurrently to collect particle counts (particles/cm3) in size range 0.02 to >1 µm from ambient air and air just inside the breathing zone of the mask (1 measurement per second, evaluation period of 1 minute per test). Percent particle removal was determined for ten home-made, fabric masks of different designs, with and without filter layers, as well as three commercially-produced surgical-type masks. N95 masks were used to validate the method, and a 3M model 1826 surgical mask was used as a baseline for comparison of other masks of this style. Home-made masks worn as designed always had lower particle removal rates than the 3M masks, achieving between 38% and 96% of this baseline. As has been previously observed by Cooper et al. (1983), adding a layer of nylon stocking over the masks minimized the flow of air around the edges of the masks and improved particle filtration efficiency for all masks, including all commercial products tested. Use of a nylon stocking overlayer brought the particle filtration efficiency for five of the ten fabric masks above the 3M surgical mask baseline. This rapid testing method (<2 hours per mask design) provides a holistic evaluation of mask particle removal efficacy (material, design, and fit), and use of this method for testing a wider range of mask materials and designs will provide the public and health care providers with information needed to optimize health protection given resources at hand.

scholarly journals Bacteria Filtration Efficiency of Different Face Masks Worn during COVID-19 Pandemic in North-Eastern Tanzania: An In Vitro Study

2020 ◽  
Author(s):  
Marianne Gnanamuttupulle ◽  
Shilanaiman Hilary Ntundu ◽  
Oliver Henke ◽  
Abias Anthon Moshi ◽  
David Msuya ◽  
...  
Keyword(s):  
Double Layer ◽  
Single Layer ◽  
In Vitro Study ◽  
Filtration Efficiency ◽  
Cotton Cloth ◽  
Bacterial Suspension ◽  
Surgical Masks ◽  
North Eastern ◽  
N95 Respirators

Increased demand for wearing face masks, lack of surgical masks and N95 respirators during the coronavirus pandemic created alternative needs for cloth masks. Therefore, to determine filtration efficacy, reusability and duration of wearing new and hand washed cloth masks, the bacteria filtration efficacy was tested using Staphylococcus aureus and Escherichia coli. Cotton cloth masks; single layer without pleats and with pleats, double layer with canvas filter in the middle, double layer with stiff filter in the middle, double layer with pleats on both sides and locally made and imported surgical masks and N95 respirators were used. Bacterial suspension was sprayed over outer surface and swabbed from inner surface at 0hrs, 4thhr, 8thhr and 12thhr. Similar procedure was performed to hand washed and ironed cotton cloth masks. After 24 hours of incubation, single layer without pleats and with pleats had no filtration efficacy(0-100%). Double layer with stiff filter in the middle and double layer with pleats on both sides had higher filtration efficacy(99.96-100%), this filtration efficacy remained up to three occasions of hand washing with soap and water, conferring protection up to 12hours. Filtration efficacy of surgical masks made locally, imported and N95 respirators were 90-100%, 99.99-100%, and 99.99-100% respectively.

scholarly journals Short Communication: Health Interventions in Volcanic Eruptions—Community Wearability Assessment of Respiratory Protection against Volcanic Ash from Mt Sinabung, Indonesia

2018 ◽  
Vol 15 (11) ◽  
pp. 2359 ◽  
Author(s):  
Karen Galea ◽  
Judith Covey ◽  
Sari Mutia Timur ◽  
Claire Horwell ◽  
Fentiny Nugroho ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Short Communication ◽  
High Efficiency ◽  
Volcanic Eruptions ◽  
The Other ◽  
Respiratory Protection ◽  
Industry Standards ◽  
Surgical Masks ◽  
Over The Top ◽  
Better Than

Inhalation of ash can be of great concern for affected communities, during and after volcanic eruptions. Governmental and humanitarian agencies recommend and distribute a variety of respiratory protection (RP), commonly surgical masks but, also, industry-certified N95-style masks. However, there is currently no evidence on how wearable they are within affected populations or how protective wearers perceive them being against volcanic ash (which will influence the likelihood of uptake of recommended interventions). Volunteers living near Mt. Sinabung, Sumatra, Indonesia, participated in a field wearability study, which included a high-efficiency mask certified to industry standards (N95-equiv.); a standard, pleated surgical mask (Surgical); a Basic flat-fold mask (Flat-fold), and the surgical mask plus a scarf tied over the top (Surgical Plus) to improve fit. These types of RP had all performed well during earlier laboratory filtration efficiency tests. The N95-equiv. mask had performed significantly better than the other RP in the subsequent total inward leakage volunteer trials, whilst the Flat-fold and Surgical masks performed poorly, letting in a third of PM2.5 particles (data published elsewhere). Thirty volunteers wore each mask for a 15-min walk before being asked to rate the comfort, breathability and perceived protection and fit of each. After wearing all of the masks, volunteers compared and identified their preferred type of protection. The feedback received from the volunteers suggested that the Surgical Plus and N95-equiv. masks were rated as being significantly hotter and more humid than other masks. The Flat-fold was rated to have better breathability than the other masks. The N95-equiv. mask was ranked as providing the best level of effectiveness of the four masks tested. Ultimately, when asked which type of mask they would choose to wear during ashfall, 33% selected the Flat-fold mask due to its comfort and simplicity, with the Surgical Plus being the least likely to be chosen of the four tested. The study findings are of benefit to agencies who need to make informed decisions on the procurement and distribution of RP for use by those affected in future eruptions and the provision of advice to communities on their usage.

scholarly journals Surgical masks decontamination for reuse by members of the public: feasibility study and development of home-based methods

2020 ◽  
Author(s):  
Mun Cheok Hong ◽  
Tan Sook Lan ◽  
Phua Soo Zeng Fiona ◽  
Lim Wei Qi ◽  
Pang Shyue Wei ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Ultraviolet Irradiation ◽  
Influenza A ◽  
H1n1 Influenza ◽  
Filtration Efficiency ◽  
The Public ◽  
Enveloped Virus ◽  
Log Reduction ◽  
Surgical Masks

Abstract This study aims to propose decontamination methods that are suitable for use by members of the public to cope with the shortage of surgical masks during the current COVID-19 pandemic. 3-ply surgical masks were subjected to different decontamination protocols (heat, chemical, ultraviolet irradiation) to assess their abilities to achieve at least 4-log reduction of two common respiratory pathogens, H1N1 Influenza A virus, a single-stranded RNA enveloped virus similar to SARS-CoV-2 and Staphylococcus aureus, a Gram-positive bacterium that is more resistant to decontamination than single stranded RNA enveloped virus. Decontaminated surgical masks were assessed for differences in breathability, particle filtration efficiency and bacteria filtration efficiency as compared with non-decontaminated masks. The number of decontamination cycles that the 3-ply surgical masks could undergo without significant changes in breathability and filtration efficiencies were also determined. It was found that surgical masks decontaminated by either soaking for 60 min in 0.5% (v/v) aqueous hydrogen peroxide solution, or 30 min of soaking in 0.05% - 0.5% (v/v) aqueous sodium hypochlorite diluted from household bleach or ultraviolet irradiation by a surface dose of 13.5 kJ/m2 were able to achieve at least a 4-log reduction of both Staphylococcus aureus and H1N1 Influenza A virus spiked on surgical mask test swatches. No significant changes in breathability and filtration efficiencies of the surgical masks were observed after ten decontamination cycles of hydrogen peroxide or diluted bleach treatment or 30 cycles of ultraviolet irradiation.

Determinants of English as language choice among Unaccompanied Migrant Children (UMC) in Makassar, Indonesia

2019 ◽  
Vol 2 (2) ◽  
pp. 1-7
Author(s):  
Andi Samsu Rijal ◽  
Andi Mega Januarti Putri
Keyword(s):  
Language Choice ◽  
Migrant Children ◽  
Immigrant Communities ◽  
The Public ◽  
International Language ◽  
Language User ◽  
Public Area ◽  
Better Than ◽  
Language Mastery

The essence of language is human activity. Communication with language is carried out through two basic human activities; speaking and listening during the interaction in a group of people. Immigrants in Makassar city communicate with immigrant communities and Makassar people. They used English and Indonesia to communicate with others. The aims of this article were to find out determinant factors of English as language choice among Unaccompanied Migrant Children (UMC) in Makassar and why they used English as their language choice to communicate with other people out of them. The data were taken from UMC in the shelter under the auspices of Makassar’s Social Office and in the public area of Makassar. This research was a qualitative approach; it was from a sociolinguistic perspective and focuses its analysis with the language choice among UMC. This research showed that most immigrants chose English as their language choice since they were in Makassar because they have acquired better than other international language and it has been mastered naturally by doing social interaction among themselves and people outside their community. UMC had more difficulties to socialize with Indonesian than the adult of Immigrants. Other than their lack of language mastery, they also have the anxiety to adapt to other immigrants and Makassar people. English was used by UMC to show their status as a foreigner who lived in a multicultural situation. Language becomes a power for a human being and it becomes a social identity for language user in one community. During the interaction of UMC in Makassar city, the role of English as an International language is shown.

MUNDANE MIRACLES IN AWADH. ENCOUNTERS WITH THE REVEALED AND THE HIDDEN

2020 ◽  
pp. 130-140
Author(s):  
Maxim B. Demchenko ◽  
Keyword(s):  
The Other ◽  
Local People ◽  
Natural Phenomena ◽  
Mughal Empire ◽  
The Public ◽  
British Raj ◽  
The Subject ◽  
Other World ◽  
Better Than

The sphere of the unknown, supernatural and miraculous is one of the most popular subjects for everyday discussions in Ayodhya – the last of the provinces of the Mughal Empire, which entered the British Raj in 1859, and in the distant past – the space of many legendary and mythological events. Mostly they concern encounters with inhabitants of the “other world” – spirits, ghosts, jinns as well as miraculous healings following magic rituals or meetings with the so-called saints of different religions (Hindu sadhus, Sufi dervishes),with incomprehensible and frightening natural phenomena. According to the author’s observations ideas of the unknown in Avadh are codified and structured in Avadh better than in other parts of India. Local people can clearly define if they witness a bhut or a jinn and whether the disease is caused by some witchcraft or other reasons. Perhaps that is due to the presence in the holy town of a persistent tradition of katha, the public presentation of plots from the Ramayana epic in both the narrative and poetic as well as performative forms. But are the events and phenomena in question a miracle for the Avadhvasis, residents of Ayodhya and its environs, or are they so commonplace that they do not surprise or fascinate? That exactly is the subject of the essay, written on the basis of materials collected by the author in Ayodhya during the period of 2010 – 2019. The author would like to express his appreciation to Mr. Alok Sharma (Faizabad) for his advice and cooperation.

scholarly journals High-Efficiency Intracavity Continuous-Wave Green-Light Generation by Quasiphase Matching in a Bulk Periodically Poled MgO:LiNbO3 Crystal

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Shaowei Chu ◽  
Ying Zhang ◽  
Bin Wang ◽  
Yong Bi
Keyword(s):  
High Efficiency ◽  
Continuous Wave ◽  
Green Light ◽  
Frequency Doubling ◽  
Green Laser ◽  
Periodically Poled ◽  
Output Stability ◽  
532 Nm ◽  
Better Than ◽  
Quasiphase Matching

908 mW of green light at 532 nm were generated by intracavity quasiphase matching in a bulk periodically poled MgO:LiNbO3 (PPMgLN) crystal. A maximum optical-to-optical conversion efficiency of 33.5% was obtained from a 0.5 mm thick, 10 mm long, and 5 mol% MgO:LiNbO3 crystal with an end-pump power of 2.7 W at 808 nm. The temperature bandwidth between the intracavity and single-pass frequency doubling was found to be different for the PPMgLN. Reliability and stability of the green laser were evaluated. It was found that for continuous operation of 100 hours, the output stability was better than 97.5% and no optical damage was observed.

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