Unmasking the Mask: Investigating the Role of Physical Properties in the Efficacy of Fabric Masks to Prevent the Spread of the COVID-19 Virus

To function as source control, a fabric mask must be able to filter micro-droplets (≥5 µm) in expiratory secretions and still allow the wearer to breathe normally. This study investigated the effects of fabric structural properties on the filtration efficiency (FE) and air permeability (AP) of a range of textile fabrics, using a new method to measure the filtration of particles in the described conditions. The FE improved significantly when the number of layers increased. The FE of the woven fabrics was generally higher, but double-layer weft knitted fabrics, especially when combined with a third (filter) layer, provided a comparable FE without compromising on breathability. This also confirmed the potential of nonwoven fabrics as filter layers in masks. None of the physical fabric properties studied affected FE significantly more than the others. The variance in results achieved within the sample groups show that the overall performance properties of each textile fabric are a product of its combined physical or structural properties, and assumptions that fabrics which appear to be similar will exhibit the same performance properties cannot be made. The combination of layers of fabric in the design of a mask further contributes to the product performance.     

Infection Prevention Mask Consisting of Nanofiber Filter and Habutae Silk Fabrics

To reduce skin irritation and allergic symptoms caused by long-term mask use, we produced a mask with a filter effect by laminating nanofibers on habutae silk fabric, a specialty of Japan’s Fukui Prefecture, using the electrospinning method. We investigated the filter characteristics of silk fabrics with different weave structures (habutae, flat crepe, and twill). We found that woven fabrics alone could not sufficiently block particles finer than 1 μm, even when the fabric layers were overlapped. Therefore, we had a nanofiber filter layer fabricated on the surface of habutae fabric by the electrospinning method at a weight of 1 g/m². The nanofibers removed more than 94% of 0.3 μm-particles, which are similar to the size of virus particles. However, the nanofiber layer was so dense that it caused an increase in pressure drop, so we made the nanofiber layer thinner and fabricated the filter on the surface of the habutae fabric at 0.5 g/m². A three-dimensional mask consisting of two woven fabrics, one with a nanofiber layer on the inside and the other with a normal woven fabric without a nanofiber layer on the outside, was fabricated and tested on 95 subjects. The subjects reported that the nanofiber habutae masks were more comfortable than nonwoven masks. Moreover, the silk woven masks did not cause allergic symptoms such as skin irritation.     

Measurement of mask leakage during CPAP in patients with obstructive sleep apnea

To improve the compliance of patients with obstructive sleep apnoea tight fitting nasal masks are necessary. It would be very useful to to measure the mask leakage during the recommended pressure for the treatment at home. We studied therefore the influence of different sizes and types of masks on the air leaks during the adaptation procedure. We investigated 20 patients, mean age 60.8 +/- 11.9 years, AHI 31 +/- 17, lowest oxygen saturation 81 +/- 10.3% mean CPAP-9.9 +/- 1.6. Randomized cross over we applied CPAP with different masks during wakefulness. The pressure was increased from 6 to 13 mbar by steps of 1 mbar. The mask leak was measured by Autoset. RESULTS: Using the best mask (selected from different sizes and different brands) the mask leak was 0.11 +/- 0.9 L/sec. If the patient used a mask (only one brand but selected from different sizes) or one standard mask the mask leak doubled respectively tripled. To reduce side effects and improve compliance we recommend therefore quantification of the mask leak to find the best fitting mask.     

Study on Preparation and Properties of Glass Fibre Fabric Reinforced Polyphenylene Sulphide Composites

In this paper, glass fiber fabric reinforced polyphenylene sulfide composites were prepared by hot pressing. The effects of glass fibre modification and hot pressing temperature on the properties of the composites were investigated using a scanning electron microscope, infrared spectrometer, universal testing machine, and DIGEYE digital imaging colour measurement system. The results show that after the treatment with a silane coupling agent, the silane coupling agent was more uniformly distributed on the surface of the glass fibres, and the bonding effect between the glass fibre fabric and polyphenylene sulphide was significantly improved. The strength of the composites increased and then decreased with the increase of hot pressing temperature, and the surface colour of the composites became darker and darker. When the hot-pressing temperature is 310 °C, the mechanical properties of glass fabric-reinforced polyphenylene sulfide composites are at their best, the tensile strength reaches 51.9 MPa, and the bending strength reaches 78 MPa.     

Environmental Impact of Surgical Masks Consumption in Italy Due to COVID-19 Pandemic

The COVID-19 pandemic suddenly changed the lifestyle of billions of people. Face masks became indispensable to protect from the contagion providing a significant environmental impact. The aim of this work is to propose possible solutions to decrease masks’ impact on the environment. For this reason, different masks (surgical and fabric) were considered, and the CO₂ emissions associated with the mask materials production were calculated. Carbon Footprint (CF) for each material composing the masks was evaluated through the database Ces Selector 2019. The software Qgis (version 2.18.20) allows us to elaborate the CO₂ emissions maps for each Italian region. Finally, for surgical masks, which are often imported from abroad, the CF related to transport was considered. It results that fabric masks are a sustainable solution to prevent contagion. The total CO₂ emission associated with the use of fabric masks from the beginning of the pandemic (March 2020) to December 2021 resulted in about 7 kton compared to 350 kton for surgical masks.     

Face Off: 3D-Printed Masks as a Cost-Effective and Reusable Alternative to N95 Respirators: A Feasibility Study

BackgroundOne of the best methods for protection against respiratory diseases is the use of an N95 mask. Supply shortages have demonstrated a significant need for effective alternatives to N95 masks. Benefits of 3D-printed respirators over N95s include reduced cost and ease of production, widespread availability, reusability/sterilizability, and customizability. 3D-printed mask designs have been downloaded thousands of times; however, there is little to no data on the efficacy of these potential alternatives.MethodsThree of the most popular 3D-printed respirator designs were modified to allow for the Occupational Safety and Health Administration (OSHA) quantitative fit testing that disperses saline into the ambient air and determines concentrations within the mask during multiple trials. Five volunteers conducted standardized fit tests of these masks, as well as an N95 and a KN95, and the results were compared.ResultsOne of the 3D-printed respirators, low poly COVID-19 face mask respirator (mask 2), achieved a fit factor greater than 100 in every trial, representing sufficient fit according to OSHA protocols. The N95 mask achieved a sufficient fit in 60% of the trials, and none of the remaining masks provided a suitable fit factor reliably according to the OSHA fit test. Further trials showed no change in fit factor when different 3D-printable plastics are used or when a widely available high efficiency particulate air (HEPA) filter was used.Conclusion3D-printed respirators provide a possible alternative to N95 masks to protect against respiratory pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Fit testing results demonstrate that certain 3D-printed mask designs may exceed the fit of N95 masks.     

Wearing masks as a protective measure for children against traffic-related air pollution: A comparison of perceptions between school children and their caregivers in Ho Chi Minh City,Vietnam

Background

Traffic-related air pollution (TRAP) problems are unlikely to be solved in the short term, making it imperative to educate children on protective measures to mitigate the negative impact on their health. Children and their caregivers may hold differing views on wearing a face mask as a safeguard against air pollution. While many studies have focused on predicting children's health-protective behaviours against air pollution, few have explored the differences in perceptions between children and their caregivers.

Objectives

To examine this, we conducted a study that compared the health beliefs of two generations and evaluated the factors that influence the use of masks by children to reduce air pollution exposure.

Methods

The study was conducted in 24 secondary schools and involved 8420 children aged 13–14 and their caregivers. We used a Health Belief Model (HBM)-based instrument containing 17-item self-administered health beliefs questionnaires to gather data. The results were analysed using hierarchical logistic regression to determine the probability of children frequently wearing masks to protect against TRAP.

Results

Our study showed both children and caregivers recognised that several factors could influence mask-wearing among children: discomfort or difficulty breathing while wearing a mask and forgetting to bring a mask when going outside; perceived threats of the poor quality of air and children's respiratory health problems; and cues to mask use (i.e., seeing most of their friends wearing facemasks and ease of finding masks in local stores). However, only children were significantly concerned with public perception of their appearance while wearing a mask. Females were more likely to wear masks, and caregivers with higher levels of education were more likely to encourage their children to wear masks. Children who commuted to schools by walking, biking, or motorbiking were also more accepting of mask-wearing than those who travelled by car or bus.

Conclusions

Children and their caregivers hold different perceptions of wearing masks to protect against air pollution. Children are more susceptible to social judgements regarding their appearance when wearing a mask.     

Impact of the type of mask on the effectiveness of and adherence to continuous positive airway pressure treatment for obstructive sleep apnea

Continuous positive airway pressure (CPAP) is the gold standard for the treatment of obstructive sleep apnea (OSA). Although CPAP was originally applied with a nasal mask, various interfaces are currently available. This study reviews theoretical concepts and questions the premise that all types of interfaces produce similar results. We revised the evidence in the literature about the impact that the type of CPAP interface has on the effectiveness of and adherence to OSA treatment. We searched the PubMed database using the search terms "CPAP", "mask", and "obstructive sleep apnea". Although we identified 91 studies, only 12 described the impact of the type of CPAP interface on treatment effectiveness (n = 6) or adherence (n = 6). Despite conflicting results, we found no consistent evidence that nasal pillows and oral masks alter OSA treatment effectiveness or adherence. In contrast, most studies showed that oronasal masks are less effective and are more often associated with lower adherence and higher CPAP abandonment than are nasal masks. We concluded that oronasal masks can compromise CPAP OSA treatment adherence and effectiveness. Further studies are needed in order to understand the exact mechanisms involved in this effect.     

Adaptation to different noninvasive ventilation masks in critically ill patients

OBJECTIVE:

To identify which noninvasive ventilation (NIV) masks are most commonly used and the problems related to the adaptation to such masks in critically ill patients admitted to a hospital in the city of São Paulo, Brazil.

METHODS:

An observational study involving patients ≥ 18 years of age admitted to intensive care units and submitted to NIV. The reason for NIV use, type of mask, NIV regimen, adaptation to the mask, and reasons for non-adaptation to the mask were investigated.

RESULTS:

We evaluated 245 patients, with a median age of 82 years. Acute respiratory failure was the most common reason for NIV use (in 71.3%). Total face masks were the most commonly used (in 74.7%), followed by full face masks and near-total face masks (in 24.5% and 0.8%, respectively). Intermittent NIV was used in 82.4% of the patients. Adequate adaptation to the mask was found in 76% of the patients. Masks had to be replaced by another type of mask in 24% of the patients. Adequate adaptation to total face masks and full face masks was found in 75.5% and 80.0% of the patients, respectively. Non-adaptation occurred in the 2 patients using near-total facial masks. The most common reason for non-adaptation was the shape of the face, in 30.5% of the patients.

CONCLUSIONS:

In our sample, acute respiratory failure was the most common reason for NIV use, and total face masks were the most commonly used. The most common reason for non-adaptation to the mask was the shape of the face, which was resolved by changing the type of mask employed.     

Fibre Optic FBG Sensors for Monitoring of the Temperature of the Building Envelope

Standard sensors for the measurement and monitoring of temperature in civil structures are liable to mechanical damage and electromagnetic interference. A system of purpose-designed fibre optic FBG sensors offers a more suitable and reliable solution—the sensors can be directly integrated with the load-bearing structure during construction, it is possible to create a network of fibre optic sensors to ensure not only temperature measurements but also measurements of strain and of the moisture content in the building envelope. The paper describes the results of temperature measurements of a building 2-layer wall using optical fibre Bragg grating (FBG) sensors and of a three-layer wall using equivalent classical temperature sensors. The testing results can be transmitted remotely. In the first stage, the sensors were tested in a climatic test chamber to determine their characteristics. The paper describes test results of temperature measurements carried out in the winter season for two multilayer external walls of a building in relation to the environmental conditions recorded at that time, i.e., outdoor temperature, relative humidity, and wind speed. Cases are considered with the biggest difference in the level of the relative humidity of air recorded in the observation period. It is found that there is greater convergence between the theoretical and the real temperature distribution in the wall for high levels (~84%) of the outdoor air relative humidity, whereas at the humidity level of ~49%, the difference between theoretical and real temperature histories is substantial and totals up to 20%. A correction factor is proposed for the theoretical temperature distribution.     

Comparison of the upper airway dynamics of oronasal and nasal masks with positive airway pressure treatment using cine magnetic resonance imaging

Purpose

It is known that oronasal masks are not as effective at opening the upper airway compared to nasal only continuous positive airway pressure (CPAP) masks in patients with sleep-disordered breathing. However, the physiological mechanism for this difference in efficacy is not known; although, it has been hypothesized to involve the retroglossal and/or retropalatal region of the upper airway. The objective of this study was to investigate differences in retroglossal and retropalatal anterior-posterior space with the use of oronasal vs. nasal CPAP masks using real-time cine magnetic resonance imaging (cMRI).

Methods

Ten subjects (eight men, two women) with obstructive sleep apnea (OSA) were given cMRI with both nasal and oronasal CPAP masks. Each subject was imaged with each interface at pressures of 5, 10, and 15 cm of H₂O, while in the supine position along the sagittal plane.

Results

The oronasal mask produced significantly less airway opening in the retropalatal region of the upper airway compared to the nasal mask interface. During exhalation, mask style had a significant effect on anterior-posterior distance p?=?0.016. No differences were found in the retroglossal region between mask styles.

Conclusions

Our study confirmed previous findings showing differences in treatment efficacy between oronasal and nasal mask styles. We have shown anatomic evidence that the nasal mask is more effective in opening the upper airway compared to the oronasal mask in the retropalatal region.

     

The efficacy of a custom-fabricated nasal mask on gas exchange during nasal intermittent positive pressure ventilation.

Commercially available nasal masks have a large mask volume and give rise to considerable air leaks around the mask during nasal intermittent positive pressure ventilation (NIPPV) which may reduce alveolar ventilation (VA per breath). The effects of a custom-fabricated nasal mask (F-mask) versus a commercially available mask (C-mask) on arterial blood gas measurements, dead space including both physiological and apparatus dead space (VD), air leak and VA per breath were compared in patients with restrictive thoracic disease during short-term NIPPV sessions while using a volume cycled ventilator with equivalent settings for both masks. The mask volume of the C-mask was significantly larger than that of the F-mask (p<0.003). The arterial carbon dioxide tension (Pa,CO2) during NIPPV with either the F-mask (5.56+/-1.35 kPa) (mean+/-SD) or the C-mask (6.87+/-0.96 kPa) was significantly lower than during spontaneous breathing (7.75+/-0.81 kPa; p<0.003), but the Pa,CO2 decreased more during NIPPV with the F-mask than with the C-mask (p<0.003). The VD was significantly smaller (p<0.03), the air leak was significantly less (p<0.03), and the VA per breath was significantly larger (p<0.03) during NIPPV with the F-mask than with the C-mask. In conclusion, nasal intermittent positive pressure ventilation with the F-mask was more effective than nasal intermittent positive pressure ventilation with the commercially available mask due to its smaller dead space and less air leak. Further studies are needed to extend these results to all the commercially available-masks.     

Prolonged Use of Surgical Masks and Respirators Affects the Protection and Comfort for Healthcare Workers

This study explored the ideal period for wearing masks to prevent the physiological and psychological problems associated with long-term face mask use during respiratory infections by healthcare workers. Breathing simulators, surgical masks (SM) and medical respirators (PM) were prepared for two to eight hours. Changes in the comfort of masks (facial skin temperature, breathing resistance, and moisture permeability) and protection (filtration efficiency, resistance to blood penetration, and colony count) were assessed. The results demonstrated that the masks offered efficient liquid-particle filtering even after eight hours of use. However, the number of bacterial colonies using PM and SM grew significantly after two and four hours, respectively. Concerning comfort, the inspiratory resistance of masks rose dramatically after two hours, whereas the moisture permeability declined considerably after four hours. In addition, skin temperature had a significant increase within two hours, which may result in facial discomfort. When conditions permitted, the hospital staff was instructed to replace their masks every two hours.     

Influence of mask design on bag-mask ventilation

Adequate positive pressure ventilation in the field or emergency department continues to represent a major challenge. A new face mask design that recently has been introduced consists of a low-pressure "balloon" through which a Guedel airway is attached and extended proximally through the mask to allow the attachment of a ventilation bag. The mask is designed to seal the nares and mouth when pressed against the face. Ventilation is achieved through the airway which extends through the mask to just above the epiglottis. We designed a study to evaluate ventilating volumes and mask leak with this mask design, and to compare these parameters with those achieved with standard masks. Thirty volunteers with varied experience in bag-mask ventilation were chosen to ventilate a specially adapted ventilation manikin connected to a test lung that was capable of simulating varied compliances. Spirometers measured volumes delivered to the ventilating bag and lung, and mask leak could be calculated from these readings. A constant rate of 12 ventilations per minute was maintained by each volunteer for two minutes. Volunteers ventilated the test lung using three masks in random sequence: the SealEasy mask (Respironics Inc, Monroeville, PA), a Laerdal mask (old type), and a transparent Robertshaw mask with inflatable black rim. The average tidal volume delivered by the SealEasy mask was consistently higher than either of the other two. Significantly (P less than .05) higher volumes were delivered with the SealEasy mask when compared to the Laerdal, and significantly lower mask leaks were seen when the SealEasy was compared to both.(ABSTRACT TRUNCATED AT 250 WORDS)     

Restoring the seal of an anatomical face mask

The face mask is a device to facilitate the delivery of gases from a breathing system to a patient by creating an airtight seal around the face. Of the many types of face masks available, the anatomical face mask is most commonly used for anaesthesia. With repeated usage, the seal of the anatomical face mask becomes flattened due to the loss of air in the cushion, leading to a poor fit on the patient's face. This results in air dilution during spontaneous respiration and inadequate gas exchange during controlled ventilation. A simple solution to restore this seal has been provided.     

Evaluation of quantitative fit-testing of N95 filtering facepiece respirators using Mask-Fitting Tester and improvement of mask fitting by instruction

OBJECTIVE: To evaluate quantitative fitness of N95 filtering facepiece respirators (N95 Mask) using Mask Fitting Tester and improvement of fitness by instruction. MATERIALS AND METHODS: One hundred and thirty-three health care workers working at our hospital were tested as to quantitative fitness of N95 Mask using Mask Fitting Tester Model MT-02, Roken type that counts particles more than 0.7 microm in diameter. Based on counting the number of particles more than 0.7 microm in diameter of the air inside and outside the mask, leakage rate is calculated. Permissible range of leakage rate is 10% or below. In case of leakage rate more than 10%, we instructed way of wearing N95 Mask or change a type of N95 Mask. We usually provide three types of N95 Mask. RESULTS: Eighty-seven (65.4%) out of 133 health care workers achieved leakage rate 10% or below at the first test. Forty-six (34.6%) who did not achieve leakage rate 10% or below at the first test received instruction or changed a mask type. Twenty-one (15.8%) achieved desired value by instruction and 19 (14.3%) by changing a mask type. But 6 (4.5 %) could not achieve desired value in spite of instruction or changing to another type of masks available to us. Leakage rate changed from 20.5 +/- 10.9% (10.1-58.6) to 6.3 +/- 4.9% (0-29.5) by instruction or changing a type of mask (p < 0.001). At the first test, mask fitness is better in male than female, and worse in workers who always use N95 Mask at isolation ward or laboratory room than workers who usually do not use N95 Mask. Main problems were choice of mask, fitness to nose, incorrect use of headband. CONCLUSION: It is useful to evaluate N95 Mask quantitative fitness using Mask Fitting Tester Model MT-02, Roken type. At the first test, 34.6% of health care workers have large amount of leakage more than 10%, and by instruction or changing a mask type, most of them could achieve 10% or below. But 4.5% could not achieve desired value. On Infection control, it is important to test quantitative fitness of N95 Mask and to provide more than three types of N95 Mask.     

Investigation on the protective value of breathing masks in farmer's lung using an inhalation provocation test

Six subjects with farmer's lung underwent double inhalation challenge tests, each lasting 60 min, using natural antigen exposure. Subjects underwent the tests first without and then with protection by a particle-filtering half mask. Our purpose was to determine whether and to what extent the use of such masks reduced or prevented symptoms in affected patients. Clinical assessment included general and pulmonary symptoms, HR, temperature, WBC count, R, ITGV, VC, TLC, PO2, DCO, and chest x-ray film. The unprotected challenge provoked late responses characteristic of extrinsic allergic alveolitis. In the challenge using the mask, all six patients reported to be completely free of symptoms. Compared with the test without a mask, a statistically significant reduction in the rise of temperature, WBCs, HR, R, TLC, and PO2 was observed. Compared with the initial values, a statistically significant reduced increase of temperature and leukocytes was demonstrated in the test using the mask. Pulmonary and systemic alterations were significantly reduced but not completely prevented by the application of the particle-filtering half mask.     

A new predictive model for continuous positive airway pressure in the treatment of obstructive sleep apnea

Background

Numerous mathematical formulas have been developed to determine continuous positive airway pressure (CPAP) without an in-laboratory titration study. Recent studies have shown that style of CPAP mask can affect the optimal pressure requirement. However, none of the current models take mask style into account. Therefore, the goal of this study was to develop new predictive models of CPAP that take into account the style of mask interface.

Methods

Data from 200 subjects with attended CPAP titrations during overnight polysomnograms using nasal masks and 132 subjects using oronasal masks were randomized and split into either a model development or validation group. Predictive models were then created in each model development group and the accuracy of the models was then tested in the model validation groups.

Results

The correlation between our new oronasal model and laboratory determined optimal CPAP was significant, r = 0.61, p < 0.001. Our nasal formula was also significantly related to laboratory determined optimal CPAP, r = 0.35, p < 0.001. The oronasal model created in our study significantly outperformed the original CPAP predictive model developed by Miljeteig and Hoffstein, z = 1.99, p < 0.05. The predictive performance of our new nasal model did not differ significantly from Miljeteig and Hoffstein’s original model, z = ?0.16, p < 0.90. The best predictors for the nasal mask group were AHI, lowest SaO2, and neck size, whereas the top predictors in the oronasal group were AHI and lowest SaO2.

Conclusion

Our data show that predictive models of CPAP that take into account mask style can significantly improve the formula’s accuracy. Most of the past models likely focused on model development with nasal masks (mask style used for model development was not typically reported in previous investigations) and are not well suited for patients using an oronasal interface. Our new oronasal CPAP prediction equation produced significantly improved performance compared to the well-known Miljeteig and Hoffstein formula in patients titrated on CPAP with an oronasal mask and was also significantly related to laboratory determined optimal CPAP.

     

Aerosol penetration through surgical masks.

BACKGROUND: Surgical masks are used in hospitals to reduce postoperative infection in patients. The presence of aerosols containing pathogens makes it desirable to protect the medical staff as well. METHODS: The collection efficiencies of surgical masks measured with two aerosol-size spectrometers. The flow rates through the masks were varied from 5 to 100 L/min to study the flow dependency. For comparison, several industrial-type respirators were also tested. RESULTS: A surgical mask consisting of filter material performed better than did a surgical mask consisting only of a shell with a coarse pore structure. The latter passed 80% of submicrometer-sized aerosols with little flow dependency, whereas the penetration of submicrometer-sized aerosols through the mask made of filter material ranged from 25% at a flow rate of 5 L/min to 70% at 100 L/min. CONCLUSIONS: The mask that has the highest collection efficiency is not necessarily the best mask from the perspective of the filter-quality factor, which considers not only the capture efficiency but also the air resistance. Although surgical mask media may be adequate to remove bacteria exhaled or expelled by health care workers, they may not be sufficient to remove the submicrometer-size aerosols containing pathogens to which these health care workers are potentially exposed.     

Moldable Mask: A Reusable,Hot Water Moldable,Additively Manufactured Mask to Be Used as an N95 Alternative

There has been high demand for personal protective equipment (PPE) during the COVID-19 pandemic, especially N95 respirators. Unfortunately, at the early stage of the pandemic, the supply could not meet the demand for N95 respirators, leading to a shortage and unsafe reuse of this form of PPE. We developed the Moldable Mask to ease the demand for N95 respirators by creating a 3D-printed mask that uses a piece of N95 material as a filter. A sheet of N95 material could be used or one N95 respirator to be turned into two masks. The main feature of the mask is the ability to easily mold it in hot water to create a custom fit for each user. It can also be easily assembled at home with affordable materials. The final mask design was qualitatively fit tested on 13 subjects, with all subjects showing an improvement in fit with the hot water molding technique and 10 (77%) subjects passing the fit test. This shows that the Moldable Mask is a viable option for a safe, affordable N95 alternative when N95 mask supply is strained.