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1.
Sci Rep ; 11(1): 24490, 2021 12 29.
Article in English | MEDLINE | ID: covidwho-1594104

ABSTRACT

During the first wave of Covid-19 infections in Germany in April 2020, clinics reported a shortage of filtering face masks with aerosol retention> 94% (FFP2 & 3, KN95, N95). Companies all over the world increased their production capacities, but quality control of once-certified materials and masks came up short. To help identify falsely labeled masks and ensure safe protection equipment, we tested 101 different batches of masks in 993 measurements with a self-made setup based on DIN standards. An aerosol generator provided a NaCl test aerosol which was applied to the mask. A laser aerosol spectrometer measured the aerosol concentration in a range from 90 to 500 nm to quantify the masks' retention. Of 101 tested mask batches, only 31 batches kept what their label promised. Especially in the initial phase of the pandemic in Germany, we observed fluctuating mask qualities. Many batches show very high variability in aerosol retention. In addition, by measuring with a laser aerosol spectrometer, we were able to show that not all masks filter small and large particles equally well. In this study we demonstrate how important internal and independent quality controls are, especially in times of need and shortage of personal protection equipment.


Subject(s)
COVID-19/prevention & control , COVID-19/transmission , Masks/statistics & numerical data , Aerosols , Filtration/instrumentation , Germany , Humans , Masks/standards , Masks/trends , N95 Respirators/standards , N95 Respirators/statistics & numerical data , Occupational Exposure/prevention & control , Pandemics/prevention & control , Personal Protective Equipment/standards , Quality Control , Respiratory Protective Devices/standards , SARS-CoV-2/pathogenicity
2.
J Occup Health ; 63(1): e12309, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1579078

ABSTRACT

BACKGROUND: With the COVID-19 pandemic, the idea of universal mask wearing to prevent infecting others when one becomes infected has prevailed among people. In general, any workplace is not exempt and workers are required to wear a mask while working at the sites. OBJECTIVES: This study aims to integrate information to assist workers to select effective protectors for the prevention of droplet infection even at workplaces without occupational health personnel. METHODS: A total of 94 studies were included in this study: 91 studies were identified in MEDLINE, which was used for the literature search, and an additional three studies were identified from other information sources. The studies were checked to eliminate duplication and narrowed down to 31 based on the titles and abstracts. The contents of the 31 studies were read through and then 19 studies were extracted for careful reading. RESULTS AND CONCLUSIONS: Regarding the protectors used at workplaces, it was suggested that (1) workers continue to use respiratory protectors as needed at sites where respiratory protectors such as an N95 respirator had to be used even before the spread of COVID-19 and (2) wear surgical masks, multi-layer cloth masks, or hybrid fabric masks made of several types of fabrics that are recommended in terms of preventing dissemination of droplets and protecting against inhalation of droplets, selected according to the working conditions, taking account of air permeability, breathability, and durability.


Subject(s)
COVID-19 , Masks/standards , Occupational Health , Workplace , Health Personnel , Humans , Pandemics , SARS-CoV-2
3.
PLoS One ; 16(9): e0255338, 2021.
Article in English | MEDLINE | ID: covidwho-1518352

ABSTRACT

Global shortages of N95 respirators have led to an urgent need of N95 decontamination and reuse methods that are scientifically validated and available world-wide. Although several large scale decontamination methods have been proposed (hydrogen peroxide vapor, UV-C); many of them are not applicable in remote and low-resource settings. Heat with humidity has been demonstrated as a promising decontamination approach, but care must be taken when implementing this method at a grassroots level. Here we present a simple, scalable method to provide controlled humidity and temperature for individual N95 respirators which is easily applicable in low-resource settings. N95 respirators were subjected to moist heat (>50% relative humidity, 65-80°C temperature) for over 30 minutes by placing them in a sealed container immersed in water that had been brought to a rolling boil and removed from heat, and then allowing the containers to sit for over 45 minutes. Filtration efficiency of 0.3-4.99 µm incense particles remained above 97% after 5 treatment cycles across all particle size sub-ranges. This method was then repeated at a higher ambient temperature and humidity in Mumbai, using standard utensils commonly found in South Asia. Similar temperature and humidity profiles were achieved with no degradation in filtration efficiencies after 6 cycles. Higher temperatures (>70°C) and longer treatment times (>40 minutes) were obtained by insulating the outer vessel. We also showed that the same method can be applied for the decontamination of surgical masks. This simple yet reliable method can be performed even without electricity access using any heat source to boil water, from open-flame stoves to solar heating, and provides a low-cost route for N95 decontamination globally applicable in resource-constrained settings.


Subject(s)
COVID-19/prevention & control , Decontamination/methods , Equipment Reuse/statistics & numerical data , Hot Temperature , Humidity , Masks/standards , N95 Respirators/standards , Asia/epidemiology , COVID-19/epidemiology , COVID-19/transmission , COVID-19/virology , Filtration , Humans , SARS-CoV-2
5.
Sci Rep ; 11(1): 19403, 2021 09 30.
Article in English | MEDLINE | ID: covidwho-1447324

ABSTRACT

The ongoing worldwide outbreak of COVID-19 has set personal protective equipment in the spotlight. A significant number of countries impose the use of facemasks in public spaces and encourage it in the private sphere. Even in countries where relatively high vaccination rates are achieved at present, breakthrough infections have been frequently reported and usage of facemasks in certain settings has been recommended again. Alternative solutions, including community masks fabricated using various materials, such as cotton or jersey, have emerged alongside facemasks following long-established standards (e.g., EN 149, EN 14683). In the present work, we present a computational model to calculate the ability of different types of facemasks to reduce the exposure to virus-laden respiratory particles, with a focus on the relative importance of the filtration properties and the fitting on the wearer's face. The model considers the facemask and the associated leakage, the transport of respiratory particles and their accumulation around the emitter, as well as the fraction of the inhaled particles deposited in the respiratory system. Different levels of leakages are considered to represent the diversity of fittings likely to be found among a population of non-trained users. The leakage prevails over the filtration performance of a facemask in determining the exposure level, and the ability of a face protection to limit leakages needs to be taken into account to accurately estimate the provided protection. Filtering facepieces (FFP) provide a better protection efficiency than surgical and community masks due to their higher filtration efficiency and their ability to provide a better fit and thus reduce the leakages. However, an improperly-fitted FFP mask loses a critical fraction of its protection efficiency, which may drop below the protection level provided by properly-worn surgical and community masks.


Subject(s)
COVID-19/prevention & control , COVID-19/transmission , Filtration/instrumentation , Masks/standards , SARS-CoV-2 , Aerosols , Air Microbiology , COVID-19/virology , Disease Transmission, Infectious/prevention & control , Filtration/standards , Humans , Inhalation Exposure/prevention & control , Models, Theoretical , Particle Size
6.
PLoS One ; 16(9): e0257468, 2021.
Article in English | MEDLINE | ID: covidwho-1406756

ABSTRACT

BACKGROUND: Face masks, also referred to as half masks, are essential to protect healthcare professionals working in close contact with patients with COVID-19-related symptoms. Because of the Corona material shortages, healthcare institutions sought an approach to reuse face masks or to purchase new, imported masks. The filter quality of these masks remained unclear. Therefore, the aim of this study was to assess the quality of sterilized and imported FFP2/KN95 face masks. METHODS: A 48-minute steam sterilization process of single-use FFP2/KN95 face masks with a 15 minute holding time at 121°C was developed, validated and implemented in the Central Sterilization Departments (CSSD) of 19 different hospitals. Masks sterilized by steam and H2O2 plasma as well as new, imported masks were tested for particle filtration efficiency (PFE) and pressure drop in a custom-made test setup. RESULTS: The results of 84 masks tested on the PFE dry particle test setup showed differences of 2.3±2% (mean±SD). Test data showed that the mean PFE values of 444 sterilized FFP2 face masks from the 19 CSSDs were 90±11% (mean±SD), and those of 474 new, imported KN95/FFP2 face masks were 83±16% (mean±SD). Differences in PFE of masks received from different sterilization departments were found. CONCLUSION: Face masks can be reprocessed with 121 °C steam or H2O2 plasma sterilization with a minimal reduction in PFE. PFE comparison between filter material of sterilized masks and new, imported masks indicates that the filter material of most reprocessed masks of high quality brands can outperform new, imported face masks of unknown brands. Although the PFE of tested face masks from different sterilization departments remained efficient, using different types of sterilization equipment, can result in different PFE outcomes.


Subject(s)
COVID-19/prevention & control , Masks , Sterilization , COVID-19/transmission , Equipment Reuse , Health Personnel , Humans , Hydrogen Peroxide , Masks/standards , SARS-CoV-2/physiology , Steam , Sterilization/standards
7.
West J Emerg Med ; 22(5): 1045-1050, 2021 Aug 17.
Article in English | MEDLINE | ID: covidwho-1405508

ABSTRACT

INTRODUCTION: The coronavirus 2019 (COVID-19) pandemic has reinforced the importance of facial protection against droplet transmission of diseases. Healthcare workers wear personal protection equipment (PPE), including face shields and masks. Plastic face shields may have advantages over regular medical masks. Although many designs of face shields exist, there is a paucity of evidence regarding the efficacy of shield designs against droplet transmissions. There is even less published evidence comparing various face shields. Due to the urgency of the pandemic and the health and safety of healthcare workers, we aimed to study the efficacy of various face shields against droplet transmission. METHODS: We simulated droplet transmission via coughing using a heavy-duty chemical spray bottle filled with fluorescein. A standard-adult sized mannequin head was used. The mannequin head wore various face shields and was positioned to face the spray bottle at either a 0°, 45°, or 90° angle. The spray bottle was positioned at and sprayed from 30 centimeters (cm), 60 cm, or 90 cm away from the head. These steps were repeated for all face shields used. Control was a mannequin that wore no PPE. A basic mask was also tested. We collected data for particle count, total area of particle distribution, average particle size, and percentage area covered by particles. We analyzed percent covered by particles using a repeated measures mixed-model regression with Tukey-Kramer pairwise comparison. RESULTS: We used least square means to estimate the percentage area covered by particles. Wearing PPE regardless of the design reduced particle transmission to the mannequin compared to the control. The LCG mask had the lowest square means of 0.06 of all face-shield designs analyzed. Tukey-Kramer pairwise comparison showed that all PPEs had a decrease in particle contamination compared to the control. LCG shield was found to have the least contamination compared to all other masks (P < 0.05). CONCLUSION: Results suggest the importance of wearing a protective covering against droplet transmission. The LCG shield was found to decrease facial contamination by droplets the most of any tested protective equipment.


Subject(s)
Aerosols/analysis , COVID-19/prevention & control , Infection Control , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Inhalation Exposure/prevention & control , Masks/statistics & numerical data , Personal Protective Equipment/statistics & numerical data , COVID-19/epidemiology , Cough , Delivery of Health Care , Humans , Manikins , Masks/standards , Particle Size , Personal Protective Equipment/standards , SARS-CoV-2
8.
MMWR Morb Mortal Wkly Rep ; 70(7): 254-257, 2021 Feb 19.
Article in English | MEDLINE | ID: covidwho-1389863

ABSTRACT

Universal masking is one of the prevention strategies recommended by CDC to slow the spread of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (1). As of February 1, 2021, 38 states and the District of Columbia had universal masking mandates. Mask wearing has also been mandated by executive order for federal property* as well as on domestic and international transportation conveyances.† Masks substantially reduce exhaled respiratory droplets and aerosols from infected wearers and reduce exposure of uninfected wearers to these particles. Cloth masks§ and medical procedure masks¶ fit more loosely than do respirators (e.g., N95 facepieces). The effectiveness of cloth and medical procedure masks can be improved by ensuring that they are well fitted to the contours of the face to prevent leakage of air around the masks' edges. During January 2021, CDC conducted experimental simulations using pliable elastomeric source and receiver headforms to assess the extent to which two modifications to medical procedure masks, 1) wearing a cloth mask over a medical procedure mask (double masking) and 2) knotting the ear loops of a medical procedure mask where they attach to the mask's edges and then tucking in and flattening the extra material close to the face (knotted and tucked masks), could improve the fit of these masks and reduce the receiver's exposure to an aerosol of simulated respiratory droplet particles of the size considered most important for transmitting SARS-CoV-2. The receiver's exposure was maximally reduced (>95%) when the source and receiver were fitted with modified medical procedure masks. These laboratory-based experiments highlight the importance of good fit to optimize mask performance. Until vaccine-induced population immunity is achieved, universal masking is a highly effective means to slow the spread of SARS-CoV-2** when combined with other protective measures, such as physical distancing, avoiding crowds and poorly ventilated indoor spaces, and good hand hygiene. Innovative efforts to improve the fit of cloth and medical procedure masks to enhance their performance merit attention.


Subject(s)
COVID-19/prevention & control , Masks/standards , COVID-19/epidemiology , COVID-19/transmission , Centers for Disease Control and Prevention, U.S. , Humans , Masks/statistics & numerical data , United States/epidemiology
10.
ACS Nano ; 14(7): 9188-9200, 2020 07 28.
Article in English | MEDLINE | ID: covidwho-1387153

ABSTRACT

Filtration efficiency (FE), differential pressure (ΔP), quality factor (QF), and construction parameters were measured for 32 cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, and 4 synthetic/cotton blends) used in cloth masks intended for protection from the SARS-CoV-2 virus (diameter 100 ± 10 nm). Seven polypropylene-based fiber filter materials were also measured including surgical masks and N95 respirators. Additional measurements were performed on both multilayered and mixed-material samples of natural, synthetic, or natural-synthetic blends to mimic cloth mask construction methods. Materials were microimaged and tested against size selected NaCl aerosol with particle mobility diameters between 50 and 825 nm. Three of the top five best performing samples were woven 100% cotton with high to moderate yarn counts, and the other two were woven synthetics of moderate yarn counts. In contrast to recently published studies, samples utilizing mixed materials did not exhibit a significant difference in the measured FE when compared to the product of the individual FE for the components. The FE and ΔP increased monotonically with the number of cloth layers for a lightweight flannel, suggesting that multilayered cloth masks may offer increased protection from nanometer-sized aerosol with a maximum FE dictated by breathability (i.e., ΔP).


Subject(s)
Coronavirus Infections/prevention & control , Masks/standards , Pandemics/prevention & control , Personal Protective Equipment/standards , Pneumonia, Viral/prevention & control , Respiratory Protective Devices/standards , Textiles/standards , Aerosols/chemistry , Betacoronavirus/pathogenicity , COVID-19 , Filtration , Humans , Masks/virology , Nanoparticles/chemistry , Nanoparticles/virology , Personal Protective Equipment/virology , Respiratory Protective Devices/virology , SARS-CoV-2 , Textiles/adverse effects , Textiles/virology
12.
PLoS One ; 15(10): e0240499, 2020.
Article in English | MEDLINE | ID: covidwho-1388890

ABSTRACT

During the current SARS-CoV-2 pandemic there is unprecedented demand for personal protective equipment (PPE), especially N95 respirators and surgical masks. The ability of SARS-CoV-2 to be transmitted via respiratory droplets from asymptomatic individuals has necessitated increased usage of both N95 respirators in the healthcare setting and masks (both surgical and homemade) in public spaces. These precautions rely on two fundamental principles of transmission prevention: particle filtration and droplet containment. The former is the focus of NIOSH N95 testing guidelines, and the latter is an FDA guideline for respirators and surgical masks. While studies have investigated droplet containment to provide guidance for homemade mask production, limited work has been done to characterize the filtration efficiency (FE) of materials used in home mask making. In this work, we demonstrate the low-cost (<$300) conversion of standard equipment used to fit-test respirators in hospital and industrial settings into a setup that measures quantitative FEs of materials based on NIOSH N95 guidelines, and subsequently measure FEs of materials found in healthcare and consumer spaces. These materials demonstrate significant variability in filtration characteristics, even for visually similar materials. We demonstrate a FE of 96.49% and pressure drop of 25.4 mmH20 for a double-layer of sterilization wrap used in surgical suites and a FE of 90.37% for a combination of consumer-grade materials. The excellent filtration characteristics of the former demonstrate potential utility for emergent situations when N95 respirators are not available, while those of the latter demonstrate that a high FE can be achieved using publicly available materials.


Subject(s)
Air Filters/standards , Betacoronavirus , Coronavirus Infections/prevention & control , Equipment Safety/methods , Masks/standards , Materials Testing/methods , Pandemics/prevention & control , Personal Protective Equipment/standards , Pneumonia, Viral/prevention & control , Respiratory Protective Devices/standards , Aerosols , COVID-19 , Coronavirus Infections/virology , Equipment Safety/instrumentation , Health Personnel , Humans , Materials Testing/instrumentation , Occupational Exposure/prevention & control , Pneumonia, Viral/virology , SARS-CoV-2
13.
Sci Rep ; 11(1): 16248, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1351978

ABSTRACT

The use of close-fitting PPE is essential to prevent exposure to dispersed airborne matter, including the COVID-19 virus. The current pandemic has increased pressure on healthcare systems around the world, leading to medical professionals using high-grade PPE for prolonged durations, resulting in device-induced skin injuries. This study focuses on computationally improving the interaction between skin and PPE to reduce the likelihood of discomfort and tissue damage. A finite element model is developed to simulate the movement of PPE against the face during day-to-day tasks. Due to limited available data on skin characteristics and how these vary interpersonally between sexes, races and ages, the main objective of this study was to establish the effects and trends that mask modifications have on the resulting subsurface strain energy density distribution in the skin. These modifications include the material, geometric and interfacial properties. Overall, the results show that skin injury can be reduced by using softer mask materials, whilst friction against the skin should be minimised, e.g. through use of micro-textures, humidity control and topical creams. Furthermore, the contact area between the mask and skin should be maximised, whilst the use of soft materials with incompressible behaviour (e.g. many elastomers) should be avoided.


Subject(s)
Computer Simulation , Masks/adverse effects , Skin Diseases/prevention & control , Face/anatomy & histology , Finite Element Analysis , Friction , Humans , Masks/standards , Skin Diseases/etiology , Skin Physiological Phenomena , User-Centered Design
14.
Ital J Dermatol Venerol ; 156(2): 220-225, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1302863

ABSTRACT

BACKGROUND: During the recent COVID-19 outbreak, masks became mandatory and shortages frequent, therefore the prevalence of non-CE (European Conformity Mark) approved masks increased in the general population. We aimed to quantify the prevalence of mask-related cutaneous side effects and the differences between CE and non-CE approved masks. METHODS: In this multicenter prospective observational study conducted from March 20, 2020 to May 12, 2020(during and after quarantine), patients attending emergency departments for a dermatological consult were clinically assessed and their masks were inspected to detect CE marks and UNI (Italian National Unification Entity) norms. Patients with history of facial dermatoses or under current treatment for facial dermatoses were excluded. RESULTS: We enrolled 412 patients (318 during quarantine and 94 after quarantine). CE-approved masks were observed 52.8% vs. 24.5%, whilst subsets of non-CE approved masks were 9.7% vs. 14.9% (Personal protective equipment (PPE)-masks), 16.4% vs. 12.8% (surgical masks [SM]), and 21.1% vs. 47.9%(non-PPE) and (non-SM masks), respectively during and after quarantine. Remarkably, non-CE-approved masks resulted in patients displaying a statistically significant higher incidence of facial dermatoses and irritant contact dermatitis compared to CE-approved masks, and these differences were mainly driven by non-PPE non-SM masks. Comparing quarantine and after quarantine periods, no statistically significant differences were found for CE-approved masks, whilst differences were detected in non-CE-approved masks regarding incidence of facial dermatoses (P<0.0001)and irritant contact dermatitis (P=0.0041). CONCLUSIONS: Masks are essential to prevent COVID-19 but at the same time higher awareness regarding mask specifications should be promoted in the general population. Non-PPE and non-SM masks should undergo more rigorous testing to prevent the occurrence of cutaneous side effects and future patients' lawsuit damages.


Subject(s)
COVID-19 , Dermatitis, Occupational/etiology , Disease Outbreaks , Facial Dermatoses/etiology , Masks/adverse effects , Personal Protective Equipment/adverse effects , COVID-19/epidemiology , Humans , Italy/epidemiology , Masks/standards , Personal Protective Equipment/standards , Prospective Studies
15.
J Hosp Infect ; 113: 180-186, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1275476

ABSTRACT

BACKGROUND: Public Health England guidance stipulates the use of filtering facepiece (FFP3) masks for healthcare workers engaged in aerosol-generating procedures. Mask fit-testing of respiratory protective equipment is essential to protect healthcare workers from aerosolized particles. AIM: To analyse the outcome of mask fit-testing across National Health Service (NHS) hospitals in the UK during the first wave of the coronavirus disease 2019 (COVID-19) pandemic. METHODS: Using the Freedom of Information Act, 137 NHS hospitals were approached on May 26th, 2020 by an independent researcher to provide data on the outcome of fit-testing at each site. FINDINGS: Ninety-six hospitals responded to the request between May 26th, 2020 to October 29th, 2020. There was a total of 86 mask types used across 56 hospitals, 13 of which were used in at least 10% of these hospitals; the most frequently used was the FFP3M1863, used by 92.86% of hospitals. Overall fit-testing pass rates were provided by 32 hospitals with mean pass rate of 80.74%. The most successful masks, in terms of fit-test failure rates, were the Alpha Solway 3030V and the Alpha Solway S-3V (both reporting mean fit-test failures of 2%). Male- and female-specific pass and failure rates were provided by seven hospitals. Across the seven hospitals, 20.1% of men tested failed the fit-test for all masks used, whereas 19.9% of women tested failed the fit-test for all masks used. Failure rates were significantly higher in staff from Black, Asian, and Minority Ethnic (BAME) backgrounds 644/2507 (25.69%) across four hospitals. CONCLUSION: Twenty percent of healthcare workers tested during the first response to the pandemic failed fit-testing for masks. A small sample revealed that this was most prominent in staff from BAME backgrounds.


Subject(s)
COVID-19/prevention & control , Health Personnel , Masks/standards , Occupational Exposure/prevention & control , Respiratory Protective Devices/standards , Female , Humans , Male , Pandemics , State Medicine , United Kingdom
16.
PLoS One ; 16(6): e0252143, 2021.
Article in English | MEDLINE | ID: covidwho-1270947

ABSTRACT

The use of face masks by the general population during viral outbreaks such as the COVID-19 pandemic, although at times controversial, has been effective in slowing down the spread of the virus. The extent to which face masks mitigate the transmission is highly dependent on how well the mask fits each individual. The fit of simple cloth masks on the face, as well as the resulting perimeter leakage and face mask efficacy, are expected to be highly dependent on the type of mask and facial topology. However, this effect has, to date, not been adequately examined and quantified. Here, we propose a framework to study the efficacy of different mask designs based on a quasi-static mechanical model of the deployment of face masks onto a wide range of faces. To illustrate the capabilities of the proposed framework, we explore a simple rectangular cloth mask on a large virtual population of subjects generated from a 3D morphable face model. The effect of weight, age, gender, and height on the mask fit is studied. The Centers for Disease Control and Prevention (CDC) recommended homemade cloth mask design was used as a basis for comparison and was found not to be the most effective design for all subjects. We highlight the importance of designing masks accounting for the widely varying population of faces. Metrics based on aerodynamic principles were used to determine that thin, feminine, and young faces were shown to benefit from mask sizes smaller than that recommended by the CDC. Besides mask size, side-edge tuck-in, or pleating, of the masks as a design parameter was also studied and found to have the potential to cause a larger localized gap opening.


Subject(s)
COVID-19/prevention & control , Face/anatomy & histology , Masks/standards , SARS-CoV-2/isolation & purification , Textiles/standards , Adolescent , Adult , Algorithms , COVID-19/epidemiology , COVID-19/virology , Child , Cohort Studies , Computer Simulation , Female , Humans , Imaging, Three-Dimensional , Male , Masks/classification , Middle Aged , Models, Theoretical , Pandemics , SARS-CoV-2/physiology , Young Adult
17.
PLoS One ; 16(6): e0252271, 2021.
Article in English | MEDLINE | ID: covidwho-1269918

ABSTRACT

Coronavirus disease 2019 (CoViD-19), with the fatality rate in elder (60 years old or more) being much higher than young (60 years old or less) patients, was declared a pandemic by the World Health Organization on March 11, 2020. A mathematical model considering young and elder subpopulations under different fatality rates was formulated based on the natural history of CoViD-19 to study the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The model considered susceptible, exposed, asymptomatic, pre-symptomatic, mild CoViD-19, severe CoViD-19, and recovered compartments, besides compartments of isolated individuals and those who were caught by test. This model was applied to study the epidemiological scenario resulting from the adoption of quarantine (isolation or lockdown) in many countries to control the rapid propagation of CoViD-19. We chose as examples the isolation adopted in São Paulo State (Brazil) in the early phase but not at the beginning of the epidemic, and the lockdown implemented in Spain when the number of severe CoViD-19 cases was increasing rapidly. Based on the data collected from São Paulo State and Spain, the model parameters were evaluated, and we obtained a higher estimation for the basic reproduction number R0 (9.24 for São Paulo State, and 8 for Spain) compared to the currently accepted estimation of R0 around 2 using the SEIR (susceptible, exposed, infectious, and recovered compartments) model. In comparison with the lockdown in Spain, the relatively early adoption of the isolation in São Paulo State resulted in enlarging the period of the first wave of the epidemic and delaying its peak. The model allowed to explain the flattening of the epidemic curves by quarantine when associated with the protective measures (face mask, washing hands with alcohol and gel, and social distancing) adopted by the population. The description of the epidemic under quarantine and protections can be a background to foreseen the epidemiological scenarios from the release strategies, which can help guide public health policies by decision-makers.


Subject(s)
Basic Reproduction Number/statistics & numerical data , Communicable Disease Control/standards , Models, Statistical , Pandemics/prevention & control , Quarantine/standards , Age Factors , Aged , Aged, 80 and over , Brazil/epidemiology , Decision Making, Organizational , Hand Disinfection/standards , Humans , Life Expectancy , Masks/standards , Masks/statistics & numerical data , Middle Aged , Pandemics/statistics & numerical data , Physical Distancing , Public Policy , Quarantine/statistics & numerical data , SARS-CoV-2/pathogenicity , Spain/epidemiology
19.
J Occup Environ Hyg ; 18(7): 334-344, 2021 07.
Article in English | MEDLINE | ID: covidwho-1254232

ABSTRACT

Homemade cloth masks and other improvised face coverings have become widespread during the COVID-19 pandemic driven by severe shortages of personal protective equipment. In this study, various alternative (mostly common household) materials, which have not traditionally been used in respiratory protective devices, were tested for particle filtration performance and breathability. Most of these materials were found of some-but rather limited-utility in facemasks. At a breathing flow rate of 30 L min-1, 17 out of 19 tested materials demonstrated collection efficiency below 50%; at 85 L min-1, only one material featured particle collection efficiency above 50%. Pressure drop values were mostly below 4 mm w.g. (observed in 89% of cases for the two flow rates), which provides comfortable breathing. Only for one fabric material (silk) tested at 85 L min-1 did the pressure drop reach 11 mm w.g. Based on these results, a three-layer facemask prototype was designed and fabricated comprised of the best performing materials. Additional tests were conducted to examine possible particle detachment/shedding from the materials used in the newly developed facemask, but no such phenomenon was observed. The prototype was evaluated on 10 human subjects using the standard OSHA-approved quantitative fit testing protocol. The mask protection level, determined as an adopted fit factor, was found to lie between that of the two commercial surgical/medical masks tested for comparison. A 10-cycle washing of the mask prototype lowered its collection efficiency across the particle size range; however, washing did not substantially affect mask breathability. The study revealed that although homemade masks offer a certain level of protection to a wearer, one should not expect them to provide the same respiratory protection as high-end commercial surgical/medical masks or-by any means-NIOSH-certified N95 filtering facepieces.


Subject(s)
COVID-19/prevention & control , Equipment Design , Filtration/instrumentation , Masks/standards , Materials Testing , Humans , Masks/supply & distribution , Occupational Exposure/prevention & control , Particle Size , Personal Protective Equipment/standards , Personal Protective Equipment/supply & distribution , Respiration , Respiratory Protective Devices/standards , Respiratory Protective Devices/supply & distribution , SARS-CoV-2 , Textiles
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