Filtering Facepiece Research Articles

Assessment of Physical and Mechanical Parameters of Spun-Bond Nonwoven Fabric.

The selection of an appropriate fabric for technical applications, such as protective masks, hinges on a thorough understanding of the fabric's physical and mechanical properties. This study addresses the challenge of selecting the optimal material structure for the upper layer of a protective mask, aiming to ensure adequate breathability while providing effective filtration against airborne particles and contaminants. We assessed and compared the physical-mechanical properties of five polymer spun-bond nonwoven fabrics from different suppliers. Our comprehensive evaluation included, as follows: a visual inspection; light permeability analysis; mass and thickness measurements; elongation and tensile strength tests; breathing resistance assessments; and filter penetration tests with paraffin oil. The results revealed significant variations in performance among the samples, with one fabric consistently outperforming the others across multiple parameters. Notably, this top-performing fabric met or exceeded the EN 149:2001+A1:2009 standard for breathing resistance and filtration efficiency and, in combination with additional filter layers, met the requirements or exceeded class FFP2 (filtering face piece). This study underscores the importance of meticulous material selection and quality control in optimizing PPE (personal protective equipment) performance and user safety, providing valuable insights for mask manufacturers and healthcare professionals.

Communications enhance sustainable intentions despite other ongoing crises

AbstractThere is an ongoing trend toward more frequent and multiple crises. While there is a clear need for behaviors to become more sustainable to address the climate crisis, how to achieve this against the backdrop of other crises is unknown. Using a sample of 18,805 participants from the UK, we performed a survey experiment to investigate if communication messages provide a useful tool in nudging intentions toward improved sustainability in the context of the COVID-19 pandemic. We found that, despite the ongoing COVID-19 crisis, media messaging resulted in increases in sustainability-related intentions for all our communication messaging conditions. Specifically, after our communication was presented, (i) almost 80% of people who were not currently recycling their surgical masks reported their intention to do so; there was a > 70% increase in both (ii) the number of people likely to pick up face mask litter and (iii) the number of people willing to disinfect and reuse their filtering facepiece (FFP) masks 4–6 times, while (iv) there was an increase by 165% in those who would wash cloth masks at 60 °C. Our results highlight that communication messaging can play a useful role in minimizing the trade-offs between multiple crises, as well as maximizing any synergies. To support this, decision-makers and practitioners should encourage the delivery of sustainability advice via multiple sources and across different types of media, while taking steps to address potential misinformation.

Effective volume of rebreathed air during breathing with facepieces increases with protection class and decreases with ambient airflow.

Wearing facepieces is discussed in the context of increasing the volume of rebreathed air. We hypothesized that rebreathed air volume increases with increasing filtering facepiece (FFP) class and that persons breathing via facepieces compensate for the additional dead-space. We have determined the effective amount of rebreathed air for a surgical masks and FFP2 and FFP3 respirators in a physical model and determined tidal volumes, breathing frequency, blood oxygen saturation, and transcutaneously measured blood carbon dioxide partial pressure (PCO2) in lung-healthy subjects breathing without and with facepieces at rest and during exercising on a recumbent ergometer. Rebreathed air volume increased with the facepieces' protection class and with increasing inspiration volume by 45 ± 2 ml to 247 ± 1 ml. Ambient airflow reduced rebreathed air volume by 17% up to 100% (all p < 0.001). When wearing facepieces, subjects increased tidal volume (p < 0.001) but not breathing frequency. Oxygen saturation was not influenced by facepieces. With FFP3 respirators PCO2 increased by up to 3.2 mmHg (p < 0.001) at rest but only up to 1.4 mmHg (p < 0.001) when exercising. Discomfort of breathing increased with increasing protection class of the facepiece but was consistently perceived as tolerable. We conclude that the amount of rebreathed air increases with increasing protection class of facepieces. Healthy adults were capable to compensate the facepieces' dead-space by adapting tidal volume at rest and during physical activity; thereby they tolerated moderate increases in PCO2. Ambient airflow may considerably reduce the amount of facepiece related rebreathed air.

Disposable surgical/medical face masks and filtering face pieces: Source of microplastics and chemical additives in the environment

The production and consumption of disposable face masks (DFMs) increased intensely during the COVID-19 pandemic, leading to a high amount of them being found in the terrestrial and aquatic environment. The main goal of this research study is to conduct a comparative evaluation of the water-leachability of microplastics (MPs) and chemical additives from various types of disposable surgical/medical face masks (MM DFMs) and filtering face pieces (FFPs). Fourier-Transform Infrared Spectroscopy was used for MPs analysis. Liquid Chromatography/High Resolution Mass Spectrometry was used to analyse analytes presented in the water-leachates of DFMs. FFPs released 3–4 times more microplastic particles compared to MM DFMs. The release of MPs into water from all tested DFMs without mechanical stress suggests potential MP contamination originating from the DFM production process. Our study for the first time identified bisphenol B (0.25–0.42 μg/L) and 1,4-bis(2-ethylhexyl) sulfosuccinate (163.9–115.0 μg/L) as leachables from MM DFMs. MPs in the water-leachates vary in size, with predominant particles <100 μm, and the release order from DFMs is MMIIR > MMII > FFP3>FFP2>MMI. The main type of microplastics identified in the water leachates of the investigated face masks was polypropylene, accounting for 93–97% for MM DFMs and 82–83% for FFPs. Other polymers such as polyethylene, polycarbonate, polyester/polyethylene terephthalate, polyamide/Nylon, polyvinylchloride, and ethylene-propylene copolymer were also identified, but in smaller amounts. FFPs released a wider variety and a higher percentage (17–18%) of other polymers compared to MM DFMs (3–7%). Fragments and fibres were identified in all water-leachate samples, and fragments, particularly debris of polypropylene fibres, were the most common MP morphotype. The findings in this study are important in contributing additional data to develop science-based policy recommendations on the health and environmental impacts of MPs and associated chemical additives originated from DFMs.

Investigating effects of FFP2 wearing during physical activity on gas exchange, metabolism and affective state using a randomized controlled trial

Concerns are repeatedly raised about possible adverse respiratory effects of wearing filtering face pieces (FFP) during physical activity. This study compared the impact of FFP type 2 (NF95) on pulmonary function, blood gas values, metabolism and discomfort during light, moderate and vigorous physical activity. Healthy adults (n = 13; 6 females, 7 males; mean 31.3, SD 5.5 years) participated in this randomized two-armed (Ergometer cycling with a FFP type 2 vs. no mask) crossover trial. Baseline cardiopulmonary exercise testing and two interventions (masked and unmasked ergometer cycling 40%, 50% and 70% VO2max, 10 min each) were separated by 48 h washout periods. Spiroergometric data (End tidal carbon dioxide partial pressure PetCO2; breathing frequency; inspiration time), blood gas analysis outcomes (capillary carbon dioxide partial pressure, pCO2) and subjective response (Breathing effort and perceived exertion) were contrasted between conditions using ANOVAs. All participants completed the crossover trial, seven started with the FFP2 condition (No adverse events or side effects). FFP2 decreased breathing frequency, prolonged inspiration time, increased perceived breathing effort and PetCO2 (p < .05). Blood pCO2 in millimetres mercury increased during exercise with 50%VO2max (mean 36.67, SD 3.19 vs. mean 38.46, SD 2.57; p < .05) and 70%VO2max (35.04, 2.84 vs. 38.17, 3.43; p < .05) but not during exercise with 40%VO2max (36.55, 2.73 vs. 38.70). Perceived exertion was not affected (p > 0.05) by mask wearing. Conclusion: Mask-induced breathing resistance decreased respiratory performance and limited pulmonary gas exchange. While FFP2 affected subjective breathing effort per se, invasive diagnostics showed that statistically significant metabolic effects are induced from moderate intensity upwards.Trial registration: DRKS-ID: DRKS00030181, Date of registration: 05/09/2022 (German Register for Clinical Trials).

Influence of different treatment conditions on the filtration performance of conventional electret melt blown non-woven and novel nano FFP2 masks.

To allow an efficient protection against viruses like the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), it is important to avoid their spreading by using filtering face pieces (FFP), which are categorized by different standards according to their filtration efficiency. In this study, we subjected six brands of FFP2 standard masks to three different conditions and subsequently analysed them for their filtration performance to evaluate potentials for reusability. The conditions comprised changes of temperature and air humidity, an exposure to isopropyl alcohol (IPA) and an autoclave sterilization. While four of six masks consisted of electrostatically treated melt blown non-wovens, two masks were fabricated using a nanofibrous multilayer system. Due to the absence of prior electrostatic treatment, the nano-masks did not show a significant change in filtration efficiency when discharged by IPA, unlike the melt blown nonwoven masks showing a significant decrease of filtration efficiency down to around 50% at a particle size of 0.3 μm. However, most melt blown masks maintained a sufficient filtration efficiency after all other treatments with even better results than the nanofibrous masks. This was particularly the case for the capacity to filter smallest particles/droplets with a size of around 0.1 μm, which is below the range of typical filtering standards and important for the retention of virally contaminated nano-aerosols or unattached viruses. After temperature/humidity variation and autoclave sterilization, melt blown masks were able to retain a filtration efficiency up to over 90% at 0.1 μm contrary to nano-masks showing a decrease down to around 70%. Based on their better filtration performance, lower price and potential reusability, we conclude that electret melt blown masks are the preferable type of FFP2 masks.

Construction of Half Masks for the Respiratory Tract Protection and the Speech Intelligibility Assessed from the Measured Suppression of Sound

Half masks (a.k.a. filtering facepieces, FFP) are personal protective equipment against dust in a work environment. Their filtration efficiency is legally regulated. Occupational safety and health services have not paid enough attention to speech disruption caused by FFPs, even though the latter could impair verbal communication and result in discomfort or increased risk of accidents. This study deals with the objective differences in speech suppression between masks of various construction belonging to the same filtration class, FFP2, and equipped with exhalation valves. We applied an objective method of white noise attenuation, suggested in our previous work. Its uniqueness lies in the fact that the acoustic apparati are applied in the whole procedure, and no human speakers/listeners participation is required. We compared seven types of masks: three moulded, one moulded with folded elements, two folded horizontally, and one vertically. We determined attenuation caused by the masks in 1/3 octave-wide bands with centre frequency from 100 Hz to 20 kHz. All the studied FFPs attenuated sound waves in a frequency range responsible for 80–90% of the perceived speech intelligibility. The attenuations of moulded masks were ca. 3 dB higher in 1–16 kHz bands than those of folded ones. The moulded mask with foldable parts for better fitting the face suppressed the high-pitch tones considerably more than the other masks. These observations were confirmed quantitatively by the cluster analysis based on the Euclidean distances between the acoustic spectra.

Capillary carbon dioxide tension increases in hospital staff wearing filtering facepiece masks: a prospective crossover study.

The COVID-19 pandemic has changed worldwide hygiene practices. In particular, the use of filtering face piece (FFP) masks markedly increased. Concerns have been raised regarding possible negative respiratory effects of wearing FFP masks. The aim of this study was to investigate gas exchange and subjective breathing effort in hospital personnel wearing FFP2 or FFP3 masks. In this prospective, single-centre, crossover study, 200 hospital workers were assigned to alternately wear FFP2 or FFP3 masks for 1 h during routine activities. Capillary blood gas analysis was performed to evaluate gas exchange while wearing the FFP masks. The primary end-point was the change in capillary partial pressure of carbon dioxide (PcCO2). In addition, capillary partial pressure of oxygen (PcO2), respiratory rate and subjective breathing effort were assessed at the end of each hour. Changes between time points and study groups were estimated using univariate and multivariate models. PcCO2 increased from 36.8±3.5 to 37.2±3.3 mmHg (p=0.047) and 37.4±3.2 mmHg (p=0.003) in individuals wearing FFP2 or FFP3 masks, respectively. Age (p=0.021) and male sex (p<0.001) were significantly associated with increased PcCO2. Similarly, the PcO2 increased from 70.7±8.4 to 73.4±8.8 mmHg (p<0.001) and 72.8±8.5 mmHg (p=0.004) in individuals wearing FFP2 or FFP3 masks, respectively. Respiratory rate and subjective breathing effort increased significantly while wearing FFP2 and FFP3 masks (p<0.001 for all analyses). The order of wearing FFP2 or FFP3 masks did not significantly affect the results. An hour of wearing FFP2 or FFP3 masks increased PcCO2 values, respiratory rate and subjective breathing effort in healthcare personnel performing routine activities.

Protective masks during the SARS-CoV-2 pandemic: Any relationship with temporomandibular disorders and orofacial pain?

Wearing protective face masks has been one of the indispensable measures to prevent droplets and aerosol particles transmission during the SARS-CoV-2 pandemic. This observational cross-sectional survey investigated the different types and modalities of protective mask wearing and the possible association with referred signs of temporomandibular disorders and orofacial pain by respondents. An online-questionnaire was developed, calibrated and administered anonymously to subjects with an age of ≥ 18 years. It consisted of different sections: demographics, type and wearing modalities of the protective masks, pain in the preauricular area, noise at the temporomandibular joints and headache. Statistical analysis was performed using statistical software STATA v16. The questionnaire received 665 replies mainly from participants aged 18-30 years (315 males, 350 females). The healthcare professionals were 37% of participants, 21.2% of them were dentists. The Filtering Facepiece 2 or 3 (FFP2/FFP3) mask was used by 334 subjects (50.3%), and 578 (87%) wore the mask with two elastics behind the ears. Pain while wearing the mask was referred by 400 participants, and 36.8% of them referred pain with a consecutive use of more than 4 hours (p = 0.042). 92.2% of participants did not report any TMJ noise. Headache associated with the FFP2/FFP3 was referred by 57.7% of subjects (p = 0.033). This survey highlighted the increased referred the presence of discomfort in the preauricular area and headache possibly associated with a prolonged use of protective face masks for more than 4 hours during the SARS-CoV-2 pandemic.

Determining the filtration effectiveness of non-standard respiratory protective devices by an ad-hoc laboratory methodology

The recent pandemic caused by COVID-19 profoundly changed people's habits. Wearing a face mask has become usual in everyday life to reduce the risk of infection from airborne diseases. At the beginning of the pandemic, the massive request of surgical or filtering face piece (FFP) masks resulted in a global shortage of these devices for the most exposed people, such as healthcare workers. Due to this high demand for respiratory protective devices, many industrial plants have partly converted to the production of face masks using adapted materials and not complying with any specific regulation (non-standard respiratory protective devices or community masks). In this work, an ad-hoc laboratory methodology has been developed to evaluate the filtration efficiency of the materials that compose the community masks using specific instrumentation. The instrumentation consists of three main tools: an aerosol generator, a specifically designed measuring chamber, and an optical particle sizer (OPS) for the measurement of aerosol concentration. The generated aerosol was sent into the measuring chamber, divided into two separate sections by the respiratory mask. The OPS measured the aerosol mass concentration upstream and downstream of the respiratory mask, and from the concentration difference the filtration efficiency was evaluated. The proposed methodology has been validated by evaluating the particle filtration efficiency (PFE) of certified respiratory masks and was then applied for the evaluation of the filtration efficiency of different types of non-standard or community masks to analyze their effectiveness in protecting from the risk of infection of airborne diseases.

Continuous versus intermittent mask use by nurses in COVID times (CIMNIC) – A CUSUM study

Objectives: The coronavirus disease 2019 pandemic has reinforced the use of personal protective equipments in healthcare settings. Although filtering face piece 2 respirators provide adequate protection from the aerosolised viral spread, their prolonged use is often associated with subjective discomfort. The study aimed to identify whether an intervening mask-free period is less harmful in terms of discomfort and desaturation when compared against continuous use for 6-h. Material and Methods: This was a prospective and interventional study. A cohort of 87 previously healthy nurses from a multidisciplinary tertiary care hospital were recruited. Study participants were subjected to continuous and intermittent (with 15 min break) mask use, each for a 2-month duration, during their 6-h clinical shifts. Baseline and post-shift oxygen saturation (SpO2) were compared in real time using cumulative sum (CUSUM) statistics. Comfort level was also assessed on a scale of 0–10 in the two groups with 10 subjective parameters. Results: Nurses have experienced a significant drop in SpO2 in both phases with 525 and 984 recordings in continuous and intermittent mask group, respectively. The mean % (2SD) saturation drop in the two groups was 4.688 (39.35) and 1.169 (2.62). The overall discomfort level was more in the continuous phase (8.89 ± 1.610) than in intermittent (7.28 ± 3.216) mask use. CUSUM statistics helped in the real-time monitoring of subjects in the intermittent mask group. Conclusions: Significant adverse health effects in healthcare workers are highlighted using objective and subjective parameters such as desaturation and discomfort levels while using protective face masks. A mask-free period of 15 min, in between their duty shifts, might help reduce the unfavourable effects without compromising efficacy.

Face masks while exercising trial (MERIT): a cross-over randomised controlled study

ObjectivesPhysical exertion is a high-risk activity for aerosol emission of respiratory pathogens. We aimed to determine the safety and tolerability of healthy young adults wearing different types of face mask...

Effect of face masks on salivary parameters and halitosis: Randomized controlled crossover trial.

Face masking is associated with self-perceived dry mouth and halitosis. Aim of the study was to measure the effect of different face masks on salivary parameters and halitosis. The randomized controlled crossover clinical trial with four periods included 40 oral healthy participants using different face masks (cloth mask, surgical mask, filtering facepiece 2 [FFP2] mask) or no mask (control) for 4h in random order. Unstimulated salivary flow rate (primary outcome) and stimulated salivary flow rate, salivary pH and buffer capacity of stimulated and unstimulated saliva (secondary outcomes, blinded), and volatile sulfur compounds (secondary outcome) were measured before and after the 4-h periods. Statistical analysis was performed by repeated measures ANOVA (p < 0.05). Of 40 randomized participants, 39 completed the study. Unstimulated salivary flow rate prior to face masking amounted to 0.6 ± 0.3ml/min. Face masking had no significant effect on unstimulated salivary flow (p=0.550). Face masking had also no significant effect on the other salivary parameters (p ≥ 0.518). The concentration of volatile sulfur compounds (VSC) prior to face masking amounted to 157.3 ± 59.7ppb. After face masking, the concentration of VSC increased slightly, but not significantly (p=0.055): 168.1 ± 76.3ppb (control), 199.3 ± 132.7ppb (cloth masks), 188.5 ± 101.1ppb (surgical masks), and 189.7 ± 90.1ppb (FFP2 masks). Four hours of face masking did not change the salivary flow rate, pH, and buffer capacity, and had no significant effect on VSC's levels. Wearing face masks does not seem to result in measurable side-effects on salivary parameters such as a reduced salivary flow rate or VSC's levels. The protocol was prospectively registered at ClinicalTrials.gov (NCT04914208) on June 4, 2021.

Does combined usage of FFP2 and Surgical mask against SARS-CoV-2 affect SpO2 values and pulse rates of dental health-care workers?

Combined use of surgical mask with filtering facepiece (FFP) 2 masks has been popular among the health-care workers. However, the effect of this preference on the vital values of individuals stays as a challenge among the professionals. The present study aimed to assess the effect of FFP2 mask versus combined use of it with surgical mask on the SpO2 values and pulse rates of individuals. This study was conducted on 20 health-care workers. The pulse rates and SpO2 values were evaluated by pulse oximeter placed in the index fingers of the participants. The participants were divided into two groups: those using the FFP2 mask and those using FFP2-surgical mask combination. Individuals wearing FFP2 mask were examined for a period of 60 min and the same examination was repeated for another period of 60 min in those using combination of FFP2 with surgical mask. The values were measured at the beginning and at 15, 30, 45, and 60 min intervals, respectively. The examinations were conducted in the rest position to obtain standardization. The observed data showed no statistical difference at all periods in either SpO2 values or pulse rates between FFP2 and FFP2-surgical mask combined groups. The SpO2 values reduced from the initial time to 15 min in the FFP2-surgical mask group. Also, in the FFP2-SM group, statistically significant increase in values was observed between 15 and 45 min and 15 and 60 min. Another increase in SpO2 value was found in the observations made between made 30 and 45 min in the same group (P < 0.05). The pulse rates of the individuals showed no statistical difference in both the groups and at all experimental periods (P > 0.05). According to the present study, wearing only the FFP2 mask or FFP2-surgical mask combination seems not to cause any effect on the SpO2 values and pulse rates of the participants.

Face Masks at the Gymnasium: Physiological Responses and Mechanical Performance Are Not Compromised by Wearing Surgical or Filtering Facepiece 2 Masks in Healthy Subjects.

Rial-Vázquez, J, Nine, I, Guerrero-Moreno, JM, Rúa-Alonso, M, Fariñas, J, Márquez, G, Giráldez-García, MA, Méndez-Bouza, KY, López-Pillado, H, Coutado-Sánchez, E, Losada-Rodríguez, A, and Iglesias-Soler, E. Face masks at the gym: physiological responses and mechanical performance are not compromised by wearing surgical or filtering facepiece 2 masks in healthy subjects. J Strength Cond Res 37(7): 1404-1410, 2023-This study explored the effects of wearing 2 types of face masks on mechanical performance and physiological responses during high-intensity resistance exercise. Twelve healthy men performed 3 workout protocols in a randomized order: wearing a surgical or filtering facepiece 2 (FFP2) mask or without a mask. Each workout consisted of 3 sets of 10 repetitions of bench press (BP) and parallel squat (SQ) with a 12 repetition maximum load, including 2 minutes of recovery between sets and exercises. Mechanical performance was evaluated through the mean propulsive velocity and the number of repetitions completed during each session. Physiological responses were the oxygen saturation (SpO2), blood lactate concentration, heart rate (HR), and HR variability. Perceived exertion was recorded after each set, and The Beck Anxiety Inventory scale was completed at the end of each workout. The number of repetitions completed and the session mean propulsive velocity {(BP [m·s-1]: surgical: 0.35 ± 0.05; FFP2: 0.36 ± 0.04; nonmask: 0.38 ± 0.06) and (SQ: surgical: 0.43 ± 0.05; FFP2: 0.40 ± 0.07; nonmask: 0.41 ± 0.05)} were similar between conditions (p > 0.05). Heart rate recorded during sessions was similar across conditions: surgical: 119 ± 14, FFP2: 117 ± 13, and nonmask: 118 ± 10 bpm (p = 0.919). Face masks had no effect on SpO2, blood lactate concentration, HR variability, perceived exertion, and anxiety values (p > 0.05). Face masks do not compromise strength performance, physiological parameters, and perceived comfort of young and healthy individuals during a high-intensity resistance training session.

Effect of FFP2/N95 facemask wear on retinal and choroidal thickness profile in healthy subjects.

To investigate the influence of non-oil 95 (N95)/filtering facepiece 2 (FFP2) facemask wear on retinal thickness, choroidal thickness (CT), retinal nerve fiber layer thickness (RNFLT), and ganglion cell layer thickness (GCLT) in healthy subjects. In this prospective study, 53 healthy participants who used FFP2/N95 facemask were enrolled. Participants underwent optical coherence tomography imaging before and at 1 and 4h following FFP2/N95 facemask wear. The last imaging session was performed 1h after FFP2/N95 removal. Retinal thickness, CT, RNFLT, and GCLT were assessed at each session. Vital parameters were also assessed. The pulse rate of the subjects significantly decreased at 1 and 4h compared to baseline values (P<0.05). No significant changes in retinal thickness, RNFLT, and GCLT were observed in the study. CT profile showed a significant increase at all measured locations except 1-mm temporal, 1-mm inferior and 2-mm inferior points following FFP2/N95 wear which turned to baseline values after FFP2/N95 removal. Pulse rate and CT changes at 4h were significantly correlated (P<0.05). Parasympathetic activation during FFP2/N95 facemask wear might have a role on elevated CT measurements in healthy individuals by virtue of increased choroidal blood flow.

How long and effective does a mask protect you from an infected person who emits virus-laden particles: By implementing one-dimensional physics-based modeling.

SARS-CoV-2 spreads via droplets, aerosols, and smear infection. From the beginning of the COVID-19 pandemic, using a facemask in different locations was recommended to slow down the spread of the virus. To evaluate facemasks' performance, masks' filtration efficiency is tested for a range of particle sizes. Although such tests quantify the blockage of the mask for a range of particle sizes, the test does not quantify the cumulative amount of virus-laden particles inhaled or exhaled by its wearer. In this study, we quantify the accumulated viruses that the healthy person inhales as a function of time, activity level, type of mask, and room condition using a physics-based model. We considered different types of masks, such as surgical masks and filtering facepieces (FFPs), and different characteristics of public places such as office rooms, buses, trains, and airplanes. To do such quantification, we implemented a physics-based model of the mask. Our results confirm the importance of both people wearing a mask compared to when only one wears the mask. The protection time for light activity in an office room decreases from 7.8 to 1.4 h with surgical mask IIR. The protection time is further reduced by 85 and 99% if the infected person starts to cough or increases the activity level, respectively. Results show the leakage of the mask can considerably affect the performance of the mask. For the surgical mask, the apparent filtration efficiency reduces by 75% with such a leakage, which cannot provide sufficient protection despite the high filtration efficiency of the mask. The facemask model presented provides key input in order to evaluate the protection of masks for different conditions in public places. The physics-based model of the facemask is provided as an online application.

Blood gas levels, cardiovascular strain and cognitive performance during surgical mask and filtering face piece application

Mask induced airway resistance and carbon dioxide rebreathing is discussed to impact gas exchange and to induce discomfort and impairments in cognitive performance. N = 23 healthy humans (13 females, 10 males; 23.5 ± 2.1 years) participated in this randomized crossover trial (3 arms, 48-h washout periods). During interventions participants wore either a surgical face mask (SM), a filtering face piece (FFP2) or no mask (NM). Interventions included a 20-min siting period and 20 min steady state cycling on an ergometer at 77% of the maximal heart rate (HR). Hemodynamic data (HR, blood pressure), metabolic outcomes (pulse derived oxygen saturation, capillary carbon dioxide (pCO2), and oxygen partial pressure (pO2), lactate, pH, base excess), subjective response (ability to concentrate, arousal, perceived exertion) and cognitive performance (Stroop Test) were assessed. Compared to NM, both masks increased pCO2 (NM 31.9 ± 3.3 mmHg, SM = 35.2 ± 4.0 mmHg, FFP2 = 34.5 ± 3.8 mmHg, F = 12.670, p < 0.001) and decreased pH (NM = 7.42 ± 0.03, SM = 7.39 ± 0.03, FFP2 = 7.39 ± 0.04, F = 11.4, p < 0.001) during exercise. The FFP2 increased blood pressure during exercise (NM = 158 ± 15 mmHg, SM = 159 ± 16 mmHg, FFP2 = 162 ± 17 mmHg, F = 3.21, p = 0.050), the SM increased HR during sitting (NM = 70 ± 8 bpm, SM = 74 ± 8 bpm, FFP2 = 73 ± 8 bpm, F = 4.70, p = 0.014). No mask showed any comparative effect on other hemodynamic, metabolic, subjective, or cognitive outcomes. Mask wearing leads to slightly increased cardiovascular stress and elevated carbon dioxide levels during exercise but did not affect cognitive performance or wellbeing.

Dry Heat as a Potential Decontamination Method on the Filtration Efficiency of Filtering Facepiece Respirators.

Filtering facepiece respirators have been widely used in the fields of occupational health and public hygiene, especially during the COVID-19 pandemic. In particular, disposable respirators have been in high demand, and the waste generated from these disposable products poses a problem for the environment. Here, we aimed to test a practical decontamination method to allow for the reuse of KN95 respirators. In this study, three types of KN95 respirators were heated at 80 °C and 90 °C for different durations (15 min, 30 min, 45 min, 1 h, 2 h, 3 h, 4 h, 6 h, 8 h, 10 h, and 24 h). The filtration efficiencies of the tested KN95 respirators before and after heating were measured, and the changes in microstructure were imaged with a scanning electron microscope (SEM). In addition, a neural network model based on the nonlinear autoregressive with external input (NARX) to predict the filtration efficiency of the KN95 respirator was established. The results show that the temperature and time of dry heating affected particle prevention. The higher the temperature and the longer the heating time, the more obvious the decline in the filtration efficiency of the respirators. When the heating temperature reached 100 °C, the respirator may be no longer suitable for reuse. These results show that a dry heat temperature between 70 °C and 90 °C, and a heating time between 30 min and 2 h is assumed to be a suitable and effective decontamination method for respirators.

Speech Impaired by Half Masks Used for the Respiratory Tract Protection.

Filtering half masks belong to the group of personal protective equipment in the work environment. They protect the respiratory tract but may hinder breath and suppress speech. The present work is focused on the attenuation of sound by the half masks known as “filtering facepieces”, FFPs, of various construction and filtration efficiency. Rather than study the perception of speech by humans, we used a generator of white noise and artificial speech to obtain objective characteristics of the attenuation. The generator speaker was either covered by an FFP or remained uncovered while a class 1 meter measured sound pressure levels in 1/3 octave bands with center frequencies 100–20 kHz at distances from 1 to 5 m from the speaker. All five FFPs suppressed acoustic waves from the octave bands with center frequencies of 1 kHz and higher, i.e., in the frequency range responsible for 80% of the perceived speech intelligibility, particularly in the 2 kHz-octave band. FFPs of higher filtration efficiency stronger attenuated the sound. Moreover, the FFPs changed the voice timbre because the attenuation depended on the wave frequency. The two combined factors can impede speech intelligibility.