TABLE 1 - uploaded by Katy-Anne Moseley
Content may be subject to copyright.
Filtration Efficiency and Pressure Drop Across Materials Tested with Aerosols of Bacillus atrophaeus and Bacteriophage MS2 (30 L/min) a
Source publication
This study examined homemade masks as an alternative to commercial face masks.
Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healt...
Contexts in source publication
Context 1
... this study, common household materials (see Table 1) were challenged with high concentrations of bacterial and viral aerosols to assess their filtration efficiencies. Surgical masks have been considered the type of mask most likely to be used by the general public, and these were used as a control. ...
Context 2
... the materials tested showed some capability to block the microbial aerosol challenges. In general, the filtration efficiency for bacteriophage MS2 was 10% lower than for B atrophaeus (Table 1). The surgical mask had the highest filtration efficiency when challenged with bacteriophage MS2, followed by the vacuum cleaner bag, but the bag's stiffness and thickness created a high pressure drop across the material, rendering it unsuitable for a face mask. ...
Similar publications
Laboratory diagnosis of new influenza A (H1N1) is crucial for managing patients and establishing control and prevention measures. We compared the diagnostic accuracies of the real time RT-PCR (rRT-PCR) test recommended for the confirmation of the new flu and the viral culture method used conventionally for viral disease with that of the rapid antig...
Significance
The pervasiveness of influenza among humans and its rapid spread during pandemics create a false sense that all humans are affected equally. In this work, we show that neighborhood-level social determinants were associated with greater burdens of pandemic influenza in 1918 and several other diseases in a major US city. We show that lit...
Introduction/purpose: A comparison of the 1918 “Spanish” influenza to the 2020 COVID–19 pandemic could shed some light on the evolution of the latter. Method: A mathematical method previously applied to the description of the behavior of the spread of COVID–19 in time is used this time to the 1918 influenza. Results: The obtained results were compa...
Citations
... Of course, this type of mask only filters air breathed in, and does not reduce virus transmission from an infected wearer to others. Testing in laboratory settings conducted at the University of Cambridge showed that a 100% cotton t-shirt showed a mean filtration efficiency of 70.7% for Bacillus atrophaeus compared to 96.4% for a surgical mask 19 . It was concluded that homemade face coverings should not be recommended to reduce transmission of infectious aerosols unless it was a last resort. ...
... It was concluded that homemade face coverings should not be recommended to reduce transmission of infectious aerosols unless it was a last resort. It can only provide effective protection if paired with other methods of virus suppression such as isolation of the infected, social distancing, immunisation and hand hygiene 19 . Whilst materials such as cotton have been shown to offer limited protection 20 , a key reason for their popularity is the comfort, and apparent breathability afforded to the wearer 21 . ...
... Substrate materials. Cotton is commonly used as a material for face masks and coverings 17,82 due to its availability, comfort, breathability, and moderate filtration performance 19,82 . Two non-woven 4-layer swab variants of size 5 × 5 cm, made of cotton, were purchased online from JFA medical Ltd in the UK. ...
The novel coronavirus pandemic (COVID-19) has necessitated a global increase in the use of face masks to limit the airborne spread of the virus. The global demand for personal protective equipment has at times led to shortages of face masks for the public, therefore makeshift masks have become commonplace. The severe acute respiratory syndrome caused by coronavirus-2 (SARS-CoV-2) has a spherical particle size of ~97 nm. However, the airborne transmission of this virus requires the expulsion of droplets, typically ~0.6–500 µm in diameter (by coughing, sneezing, breathing, and talking). In this paper, we propose a face covering that has been designed to effectively capture SARS-CoV-2 whilst providing uncompromised comfort and breathability for the wearer. Herein, we describe a material approach that uses amorphous silica microspheres attached to cotton fibres to capture bioaerosols, including SARS CoV-2. This has been demonstrated for the capture of aerosolised proteins (cytochrome c, myoglobin, ubiquitin, bovine serum albumin) and aerosolised inactivated SARS CoV-2, showing average filtration efficiencies of ~93% with minimal impact on breathability.
... whether viral transmission could elicit infection in others) or the use of unsoiled masks (most people during the SARS-CoV-2 pandemic did not replace their mask every five minutes, the latter being the maximum duration of mask use in the study in question). Another (pre-pandemic) study investigating the filtration efficiency of different types of mask, including surgical and fabric-based homemade mask varieties, concluded that the latter offered limited filtration compared to the former [18]. Despite the carefully executed experiments, and like the previously cited work, many aspects of the study are not directly translatable to real-world conditions, including not accounting for peripheral escape, prolonged mask use, or correlation with infectiousness. ...
In this perspective, we review the evidence for the efficacy of face masks to reduce the transmission of respiratory viruses, specifically severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and consider the value of mandating universal mask wearing against the widespread negative impacts that have been associated with such measures. Before the SARS-CoV-2 pandemic, it was considered that there was little to no benefit in healthy people wearing masks as prophylaxis against becoming infected or as unwitting vectors of viral transmission. This accepted policy was hastily reversed early on in the pandemic, when districts and countries throughout the world imposed stringent masking mandates. Now, more than three years since the start of the pandemic, the amassed studies that have investigated the use of masks to reduce transmission of SARS-CoV-2 (or other pathogens) have led to conclusions that are largely inconsistent and contradictory. There is no statistically significant or unambiguous scientific evidence to justify mandatory masking for general, healthy populations with the intention of lessening the viral spread. Even if mask wearing could potentially reduce the transmission of SARS-CoV-2 in individual cases, this needs to be balanced against the physical, psychological and social harms associated with forced mask wearing, not to mention the negative impact of innumerable disposed masks entering our fragile environment. Given the lack of unequivocal scientific proof that masks have any effect on reducing transmission, together with the evident harms to people and the environment through the use of masks, it is our opinion that the mandatory use of face masks in the general population is unjustifiable and must be abandoned in future pandemic countermeasures policies.
... Compelling data and experimental studies on humans and manikins demonstrate that masking is an effective tool in mitigating SARS-CoV-2 airborne and droplets transmission [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The clinical efficacy of a face mask is determined by the filtration efficacy of the material, fit of the mask, and compliance to wearing the mask [8,14,27]. ...
... The pressurized droplets or aerosol particles are likely to escape directly from the gap between the mask and the human face due to poor fit. Inward protection, also known as wearer protection, is the capability of masks to act as a barrier to protect the uninfected wearers from respiratory droplets and aerosol particles, to penetrate through and land on exposed mucous membranes of the eye, nose, and mouth [14,17,18,24,32]. [33,34] finds that cloth masks have limited inward protection in healthcare settings where viral exposure is high compared to surgical masks and N95 respirators. ...
Masks have remained an important mitigation strategy in the fight against COVID-19 due to their ability to prevent the transmission of respiratory droplets between individuals. In this work, we provide a comprehensive quantitative analysis of the impact of mask-wearing. To this end, we propose a novel agent-based model of viral spread on networks where agents may either wear no mask or wear one of several types of masks with different properties (e.g., cloth or surgical). We derive analytical expressions for three key epidemiological quantities: The probability of emergence, the epidemic threshold, and the expected epidemic size. In particular, we show how the aforementioned quantities depend on the structure of the contact network, viral transmission dynamics, and the distribution of the different types of masks within the population. Through extensive simulations, we then investigate the impact of different allocations of masks within the population and tradeoffs between the outward efficiency and inward efficiency of the masks. Interestingly, we find that masks with high outward efficiency and low inward efficiency are most useful for controlling the spread in the early stages of an epidemic, while masks with high inward efficiency but low outward efficiency are most useful in reducing the size of an already large spread. Last, we study whether degree-based mask allocation is more effective in reducing the probability of epidemic as well as epidemic size compared to random allocation. The result echoes the previous findings that mitigation strategies should differ based on the stage of the spreading process, focusing on source control before the epidemic emerges and on self-protection after the emergence.
... virus-laden droplets and the inhalation of these droplets by the wearer (Steinbrook, 2021). The filtration efficiency of a material depends on a variety of factors such as the structure and composition of the material, as well as the size, velocity, shape, and physical properties of the particles to which it is exposed (Davies et al., 2013). Filtration efficiency is usually stated in terms of the percentage of particles of a certain size that would be stopped and retained by a filter medium (Purchas & Sutherland, 2007). ...
Due to the abundance of microplastic pollution created by improper mask disposal, there is a need for more environmentally sustainable materials to be incorporated into facemasks. The study aims to test the viability of Ti (Cordyline fruticosa) leaves as a material for facemask layers. Ti leaf mask layers were produced through mercerizing the leaves, blending them into pulp then finally making into layers through a deckle then baked in an oven. The outer layer was tested for water repellency using the AATCC water repellency test, inner layer was tested for water absorbency using the water absorbency test, while the middle layer is to be tested for filtration efficiency by sending samples to the Department of Science and Technology. All layers were also tested for tensile strength using the tensile strength test. It was found that the Ti leaf layer, compared to the surgical facemask, was significantly less water repellent and significantly more water absorbent. Additionally, it was significantly weaker in tensile strength than the outer and inner control layers, except for the middle layer in which there was no significant difference. DOST's filtration efficiency machine is not yet available and no results have been collected yet. The Ti leaf layer has the potential to be an alternative for the standard facemask's middle layer if the filtration efficiency results come to be either significantly more efficient or not different. It also has the potential to be an alternative for the middle layer if its tensile strength is improved.
... Todo esto nos sugiere, que se implemente la realización de pruebas rutinarias para evaluar si los trabajadores usan correctamente la mascarilla (30) . Además, el uso de una mascarilla KN95 será siempre una mejor opción que la quirúrgica y en caso no contar con este tipo, se recomendaría el uso de doble mascarilla quirúrgica sobre las mascarillas de tela (31) . ...
Introduction:
The COVID-19 pandemic led to massive use of personal protective equipment (PPE). However, evidence on the frequency of appropriate use is sparse. In this study, we evaluated the level of knowledge about COVID-19 and biosafety measures, and the frequency of correct use of masks in workers at a university in Lima, Peru.
Methods:
Cross-sectional study conducted in a population of 109 workers of a private university who were physically onsite. We used a structured questionnaire to measure knowledge of COVID-19, together with use of and training in PPE. In addition, we explored factors associated with the correct use of masks and an adequate level of knowledge about COVID-19 and related biosafety measurSpain. Results were expressed as prevalence, using student's T-test and Pearson chi-square tests.
Results:
We evaluated 82 workers, 35.4% of whom showed an adequate level of knowledge about COVID-19 and biosafety measurSpain. Younger participants and those who regularly washed their hands at work had an adequate level of knowledge, with 90.2% of these reporting correct use of their masks. Workers in general service areas or with a low level of education reported less frequent correct use of their mask compared to those who did not have these characteristics. Conclusion: We found a low level of knowledge about COVID-19 and biosafety measures among the workers of a private university; a higher level of education was associated with a greater prevalence of correct mask use. Training programs by work areas are needed, to improve biosafety practices among workers.
... Home-made cotton face mask avoids one from touching the nose and mouth unintentionally reducing chance of transmission of SARS-CoV-2 albeit meagrely. Cotton mask has been shown to significantly reduce droplets along with transmission of respiratory particles upon talking, coughing albeit its efficiency remains one-third of surgical mask 6 . It enables to be reused after cleaning hence is costeffective. ...
not available Bangladesh Journal of Medical Science Vol. 22 No. 02 April’23 Page : 454-456
... virus-laden droplets and the inhalation of these droplets by the wearer (Steinbrook, 2021). The filtration efficiency of a material depends on a variety of factors such as the structure and composition of the material, as well as the size, velocity, shape, and physical properties of the particles to which it is exposed (Davies et al., 2013). Filtration efficiency is usually stated in terms of the percentage of particles of a certain size that would be stopped and retained by a filter medium (Purchas & Sutherland, 2007). ...
... Various exhaled bacteria, e.g., Bacillus, Staphylococcus, and Acinetobacter spp. from patients, were also successfully achieved by mask sampling [26][27][28]. These studies show the convenience of wearable breath sampling and the unique feature that could prevent airborne transmission of exhaled virus/bacteria. ...
... Schorer et al. [16] investigated the microdroplets, proteins, and viruslike particles sprayed onto surgical masks via infrared (IR) spectroscopy, showing that the IR optical technique is a promising tool for direct virus detection at the surface of masks. Davies et al. [27] applied Henderson apparatus (HA) to test the effectiveness of homemade cotton T-shirt fabric surgical masks using Bacillus atrophaeus, bacteriophage MS2 produced during coughing. A flame photometer (FP) was used to determine the concentration of certain sodium ions that were collected by a modified mask [82]. ...
Human exhaled breath is becoming an attractive clinical source as it is foreseen to enable noninvasive diagnosis of many diseases. Because mask devices can be used for efficiently filtering exhaled substances, mask-wearing has been required in the past few years in daily life since the unprecedented COVID-19 pandemic. In recent years, there is a new development of mask devices as new wearable breath samplers for collecting exhaled substances for disease diagnosis and biomarker discovery. This paper attempts to identify new trends in mask samplers for breath analysis. The couplings of mask samplers with different (bio)analytical approaches, including mass spectrometry (MS), polymerase chain reaction (PCR), sensor, and others for breath analysis, are summarized. The developments and applications of mask samplers in disease diagnosis and human health are reviewed. The limitations and future trends of mask samplers are also discussed.
... where η I and η t are the exhalation and inhalation filtration efficiency for infectors and susceptible individuals. It is reported that the filtration efficiency of ordinary medical surgical masks is about 50% (Davies et al. 2013). f I and f t are the fraction of infectors and susceptible individuals who wear masks. ...
The present study develops a cost-effectiveness assessment model to analyze the performance of major operational parameters of central HVAC systems in terms of airborne transmission risk, energy consumption, and medical and social cost. A typical multi-zone building model with a central HVAC system is built numerically, and the effect of outdoor air (OA) ratio (from 30% to 100%) and filtration level (MERV 13, MERV 16, and HEPA) are assessed under the conditions of five climate zones in China. Compared with the baseline case with 30% OA and MERV 13 filtration, the airborne transmission risk in zones without infector is negligibly reduced with the increase in OA ratio and the upgrade of filtration level, owing to their slight modification on the equivalent ventilation rate of virus-free air. However, depending on climate zone, a 10% increase in OA ratio results in 12.5%–78.6% and 0.1%–8.6% increase in heating and cooling energy consumption, respectively, while an upgrade of filtration level to MERV 16 and HEPA results in an increase of 0.08%–0.2% and 1.4%–2.6%, respectively. Overall, when compared to the use of 100% OA ratio and HEPA filtration, the application of 30% or 40% OA ratio and MERV 13 filtration would save annually an energy and facility related cost of $29.4 billion in China, though giving an increase of approximately $0.1 billion on medical and social cost from the increased number of confirmed cases. This study provides basic method and information for the formulation of cost-effective operational strategies of HVAC systems coping with the airborne transmission, especially in resource-limited regions.
... The mask index was assumed to be 0.25 if everyone was wearing a mask in the space. equal to 0.56 and 1 if 50% or 100% of the people inside are wearing a mask [78]. is the initial infection rate, as previous studies [77] have shown that the B value varied from 0.01 to 0.1. ...
During the SARS-CoV-2 (COVID-19) pandemic, governments around the world have formulated policies requiring ventilation systems to operate at a higher outdoor fresh air flow rate for a sufficient time, which has led to a sharp increase in building energy consumption. Therefore, it is necessary to identify an energy-efficient ventilation strategy to reduce the risk of infection. In this study, we developed an occupant-number-based model predictive control (OBMPC) algorithm for building ventilation systems. First, we collected the occupancy and Heating, ventilation, and air conditioning system (HVAC) data from March to July 2021. Then, four different models (Auto regression moving average-based multilayer perceptron (ARMA_MLP), Recurrent neural networks (RNN), Long short-term memory networks (LSTM), and Nonhomogeneous Markov with change points detection (NH_Markov)) were used to predict the number of room occupants from 15 min to 24 h ahead with an interval output. We found that each model could predict the number of occupants with 85 % accuracy using a one-person offset. The accuracy of 15 min of the ahead prediction could reach 95 % with a one-person offset, but none of them could track abrupt changes. The occupancy prediction results were used to calculate the ventilation demand using the Wells-Riley equation, and the upper bound can maintain an infection risk lower than 2 % for 93 % of the day. This OBMPC model could reduce the coil load by 52.44 % and shift the peak load by 3 h up to 5 kW compared with 24 × 7 h full outdoor air (OA) system when people wear masks in the space. The occupancy prediction uncertainty could cause a 9 % to 26 % difference in demand ventilation, a 0.3 °C to 2.4 °C difference in zone temperature, a 28.5 % to 44.5 % difference in outdoor airflow rate, and a 10.7 % to 28.2 % difference in coil load.
