Filtration Efficiency Of Masks Research Articles

Riboflavin based setup as an alternative method for a preliminary screening of face mask filtration efficiency

Face masks are essential in reducing the transmission of respiratory infections and bacterial filtration efficiency, a key parameter of mask performances, requires the use of Staphylococcus aureus and specialised staff. This study aims to develop a novel method for a preliminary screening of masks or materials filtration efficiency by a green, easy and rapid setup based on the use of a riboflavin solution, a safe autofluorescent biomolecule. The proposed setup is composed of a commercial aerosol generator commonly used for aerosol therapy, custom 3D printed aerosol chamber and sample holder, a filter for downstream riboflavin detection and a vacuum pump. The filtration efficiency of four different masks was assessed using the riboflavin-based setup and the bacterial filtration efficiency (BFE). The averaged filtration efficiency values, measured with both methods, were similar but were higher for the riboflavin-based setup (about 2% for all tested samples) than bacterial filtration efficiency. Considering the good correlation, the riboflavin-based setup can be considered validated as an alternative method to bacterial filtration efficiency for masks and related materials fabrics filtration efficiency screening but This study aims to develop a novel method for a preliminary screening of masks or materials filtration efficiency by a green, easy and rapid setup based on the use of a riboflavin solution, a safe autofluorescent biomolecule, but not to replace regulation approaches. The proposed setup can be easily implemented at low price, is more rapid and eco-friendly and can be performed in chemical-physical laboratories without the needing of biosafety laboratory and specialised operators.

Do Surface Charges on Polymeric Filters and Airborne Particles Control the Removal of Nanoscale Aerosols by Polymeric Facial Masks?

The emergence of facial masks as a critical health intervention to prevent the spread of airborne disease and protect from occupational nanomaterial exposure highlights the need for fundamental insights into the interaction of nanoparticles (<200 nm) with modern polymeric mask filter materials. While most research focuses on the filtration efficiency of airborne particles by facial masks based on pore sizes, pressure drop, or humidity, only a few studies focus on the importance of aerosol surface charge versus filter surface charge and their role in the net particle filtration efficiency of mask filters. In this study, experiments were conducted to assess mask filter filtration efficiency using positively and negatively charged polystyrene particles (150 nm) as challenge aerosols at varying humidity levels. Commercial masks with surface potential (Ψf) in the range of -10 V to -800 V were measured by an electrostatic voltmeter and used for testing. Results show that the mask filtration efficiency is highly dependent on the mask surface potential as well as the charge on the challenge aerosol, ranging from 60% to 98%. Eliminating the surface charge results in a maximum 43% decrease in filtration efficiency, emphasizing the importance of electrostatic charge interactions during the particle capture process. Moreover, increased humidity can decrease the surface charge on filters, thereby decreasing the mask filtration efficiency. The knowledge gained from this study provides insight into the critical role of electrostatic attraction in nanoparticle capture mechanisms and benefits future occupational and environmental health studies.

How much natural ventilation rate can suppress COVID-19 transmission in occupancy zones?

Previous research has emphasized the importance of efficient ventilation in suppressing COVID-19 transmission in indoor spaces, yet suitable ventilation rates have not been suggested. This study investigated the impacts of mechanical, natural, single-sided, cross-ventilation, and three mask types (homemade, surgical, N95) on COVID-19 spread across eight common indoor settings. Viral exposure was quantified using a mass balance calculation of inhaled viral particles, accounting for initial viral load, removal via ventilation, and mask filtration efficiency. Results demonstrated that natural cross-ventilation significantly reduced viral load, decreasing from 10,000 to 0 viruses over 15 minutes in a 100 m2 space by providing ~1325 m3/h of outdoor air via two 0.6 m2 openings at 1.5 m/s wind speed. In contrast, single-sided ventilation only halved viral load at best. Natural cross-ventilation with masks effectively suppressed airborne viruses, lowering potential infections and disease transmission. The study recommends suitable ventilation rates to reduce COVID-19 infection risks in indoor spaces.

New approach in evaluating mask filtration efficiency using low-cost PM2.5 sensor and mobile mannequin method

Technological and industrial developments have resulted in air pollution, which can have severe health implications, particularly in the form of respiratory disease caused by particulate matter (PM). This study aims to develop a mask filtration measurement system using a mannequin simulator. The PM2.5 sensors are utilized to measure and compare pollution levels when a mask is worn versus when it is not. The test equipment is designed to collect data while driving a motorcycle outdoors, providing an accurate representation of pollution exposure to a motorcyclist. The masks tested include N95, cloth, and KN95, and both static and mobile testing is conducted. Results showed that indoor static tests filtered PM2.5 up to 80% for both N95 and cloth masks, while outdoor filtration of the N95 mask was only 72%. This difference highlights the need for a new way of evaluating mask effectiveness, and the study's mannequin-based measurements provide an effective method. The masks tested in this study demonstrated effective filtration ranging from 60% to 85%, depending on the mask type.

Are face masks effective despite peripheral gaps?

Simulations using a reduced-order model estimate face mask filtration efficiency.

Filtration efficiency of makeshift material masks vs. surgical/procedure masks and/or filtering facepiece respirators: a narrative review

Background and Objective: Face mask requirements continue to evolve on local, state, and federal levels. While surgical masks and high-filtration respirators provide higher levels of protection than makeshift material (e.g., cloth) masks, it is difficult to quantitatively compare reported filtration efficiency across different studies due to the variability in study methodologies. The objective of this review is to compare filtration efficiency of homemade face masks constructed from materials readily available within a common household to surgical/procedure masks and/or filtering facepiece respirator (FFR) controls. This analysis will provide researchers an overview of the current literature on mask filtration efficiency and underscore methodological limitations to inform future research efforts.

A Review on 3D Augmented Reality Design Technique and Inward Leakage Testing on Protective Face Mask

Protective face mask identification is essential today to users as it is a prominent protective wearable to shield from being infected by Covid-19 viruses. Protective face masks consist of layers of fibers that can capture large respiratory droplets and microscopic particles such as viruses or dust. Thus, mask filtration efficiency results depend on the materials used for each layer. Detail about mask description and efficiency are still anonymous to users, which is vital in this COVID-19. Therefore, this paper reviews designing 3D augmented reality for the protective mask with its detail parameter and mask sizing recommendation on android mobile. About 73 articles on the protective face mask, 3D augmented reality modeling, masks inward leakage testing, breathing resistance, and measuring faces have been reviewed. The result examines the existing protective face mask, inward leakage testing parameter, breathing resistance parameters, 3D modeling techniques, mobile applications, and the application used for measuring faces. The identified result shows six recent and familiar masks with 8% of arithmetic mean for inward leakage testing. The best flow efficiency is determined a 0.3 Microns bigger than 95%. The result also shows a detailed parameter for inward leakage testing in terms of inhalation resistance and flow rate. The comparison for 3D AR parameters is identified for application type, evaluated parameter, technical support parameter, AR platform, and software. This research is significant for developing AR mobile applications that ease and transparency information to the community for safety and health issues in Malaysia.

Fitted containment efficiency of face masks for reducing emission of aerosols in the indoor environment

Background: Face masks are a major tool for reducing the spread of COVID-19 has been the use of face masks because (1) they protect the wearer from aerosol laden virus in the environment and (2) they reduce aerosol emissions to the environment from infected individuals. Methods that quantify the fitted mask filtration efficiency for protection of the wearer are well established (eg, Sickbert-Bennett et al, JAMA Intern Med 2020;180:1607). In contrast, current methods for assessing face-mask containment efficiency are generally semiquantitative and rely on measurement of a very low concentration of aerosols emitted from a healthy or infected human, or the use of mannequins in which a high concentration of surrogate aerosols can be introduced inside the mask. Methods: Expanding on our standard methods used for fitted face-mask filtration efficiency, we designed a small-volume, low-ventilation chamber to accommodate a seated study participant. The study participant wore a ported face mask to allow introduction of a stream of 0.05 μm NaCl particles at a constant concentration (TSI 8026 particle generator) into the mask space. The ambient chamber concentration was continuously measured by a TSI 3775 condensation particle counter sampling 2 feet (~2 m) in front of the participant’s head over a series of three 3-minute periods: (1) resting, (2) reading out loud, and (3) repeated forceful coughing (2 × 10 coughs) (~450 L/min peak flows). Figure 1 shows a raw data sample for the coughing procedure. Containment efficiency (%) for each mask and procedure were determined as 100 × (1 – the average of all 1 − second ambient concentration values between 30 and 180 seconds divided by the same for the “no mask” condition). Results: Table 1 shows the average % containment efficiency for 2 study days with each mask or procedure in an adult male. The 2-ear-loop masks (KN95 and procedure) tested during coughing had the greatest reduction in % containment efficiency compared to that during resting breathing, likely owing to a decreased mask fit with transient pressure increase inside the mask associated with the coughs. The N95 was least affected by the introduction of reading and/or coughing, maintaining near 95% containment efficiency throughout. Conclusions: Our preliminary data on fitted containment efficiency of masks under different conditions suggest that the fitted containment efficiency closely mimics their performance for personal protection. This information that may aid in providing optimum source control in indoor environments.Funding: NoneDisclosures: None

Investigation The Bacterial Filtration Efficiency Of Medical Masks From Polyethylene Terephthalate (PET) Fabric

The Covid-19 pandemic period caused attention to the importance of medical masks. Various studies show that mask fabrics should not be ordinary. Uncontrollably produced masks with poor quality have become an important problem in the market. Based on the idea that viruses spread by binding themselves to environmental bacteria and water droplets, it is assumed that the basic filtering efficiency of masks is of primary importance and requires the use of masks with a certain filtering ability. The purpose of the present study was to produce fabric masks from Polyethylene Terephthalate (PET), and to investigate the filtration efficiency. Masks were produced from the developed PET fabric and widely used Meltblown (MB) fabric, which is known to have a high filtration rate and their filtration efficiencies were compared. EN 14683 BFE methods was used in laboratory setting to measure the filtration efficiency of the masks. It was found that the MB/3-layer mask had 99.7% (SD±0.2) capacity of filtering microorganisms and the 3-layer ART/Mask in the developed PET structure was capable of filtering microorganisms at a rate of 96.8% (SD±2.7). When the filtration efficiency of the masks detected for each microorganism was compared separately, no statistically significant differences were detected (p>0.05). The tested mask was found to have a similar high microbial filtration rate to the mask made of meltblown fabric. This suggests that it will reduce the spread of viruses by attaching themselves to bacteria from sick individuals. It is also it can has protective effect for nosocomial infections.

Comparison of effectiveness of enhanced infection countermeasures in different scenarios, using a dynamic-spread-function model.

When formulating countermeasures to epidemics such as those generated by COVID-19, estimates of the benefits of a given intervention for a specific population are highly beneficial to policy makers. A recently introduced tool, known as the "dynamic-spread" SIR model, can perform population-specific risk assessment. Behavior is quantified by the dynamic-spread function, which includes the mechanisms of droplet reduction using facemasks and transmission control due to social distancing. The spread function is calibrated using infection data from a previous wave of the infection, or other data felt to accurately represent the population behaviors. The model then computes the rate of spread of the infection for different hypothesized interventions, over the time window for the calibration data. The dynamic-spread model was used to assess the benefit of three enhanced intervention strategies - increased mask filtration efficiency, higher mask compliance, and elevated social distancing - in four COVID-19 scenarios occurring in 2020: the first wave (i.e. until the first peak in numbers of new infections) in New York City; the first wave in New York State; the spread aboard the Diamond Princess Cruise Liner; and the peak occurring after re-opening in Harris County, Texas. Differences in the efficacy of the same intervention in the different scenarios were estimated. As an example, when the average outward filtration efficiency for facemasks worn in New York City was increased from an assumed baseline of 67% to a hypothesized 90%, the calculated peak number of new infections per day decreased by 40%. For the same baseline and hypothesized filtration efficiencies aboard the Diamond Princess Cruise liner, the calculated peak number of new infections per day decreased by about 15%. An important factor contributing to the difference between the two scenarios is the lower mask compliance (derivable from the spread function) aboard the Diamond Princess.

A highly efficient cloth facemask design

Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with less consideration given to mask design and shape. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency toward expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity and expansion of the breath-mask contact area. We further assess the performance of a new reusable cloth facemask design, originally made for, but not exclusive to, professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols >0.5 microns in diameter from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. Air exchange between the mask deadspace and the ambient environment limits the extent of CO2 buildup and in inhaled air and maintains O2 levels near ambient. The mask design also provides for less inhibited mouth and jaw movement and lower relative humidity, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.Copyright © 2021 American Association for Aerosol Research

Preliminary Evaluation of Filtration Efficiency and Differential Pressure ASTM F3502 Testing Methods of Non-Medical Masks Using a Face Filtration Mount.

Research surrounding the mandated use of non-medical fabric masks is inconsistent and often confusing when compared to the standard N95. A recently published standard from ASTM International and the Centers for Disease Control and Prevention attempts to normalize evaluation procedures. The purpose of this study is to conduct a preliminary evaluation of the new methods for testing filtration efficiency of masks outlined by ASTM International F3502, where results can be directly compared to standards outlined for non-medical fabric masks. Eleven consumer non-medical fabric masks were tested for filtration efficiency and airflow resistance using a face filtration mount in accordance with the newly released ASTM International standard for facial barriers. The mean FE% (SD) ranged from 0.46% (0.44) to 11.80% (2.76) with the 3-layer athletic mesh having the highest performance and the highest deviations. All the masks tested following the procedure failed to meet to minimum FE of 20%; however all masks performed below the minimum upper limits for airflow resistance. Using a non-medical fabric masks as the sole mitigation strategy may not be as effective, as previously reported. With efforts to standardize and regulate the non-medical fabric mask market, this study demonstrates a variety of currently available consumer mask products do not meet the minimum standards nor are these remotely close to the standards of surgical or N95 masks.

A scalable method of applying heat and humidity for decontamination of N95 respirators during the COVID-19 crisis.

A lack of N95 Filtering Facepiece Respirators (FFRs) during the COVID-19 crisis has placed healthcare workers at risk. It is important for any N95 reuse strategy to determine the effects that proposed protocols would have on the physical functioning of the mask, as well as the practical aspects of implementation. Here we propose and implement a method of heating N95 respirators with moisture (85°C, 60-85% humidity). We test both mask filtration efficiency and fit to validate this process. Our tests focus on the 3M 1860, 3M 1870, and 3M 8210 Plus N95 models. After five cycles of the heating procedure, all three respirators pass both quantitative fit testing (score of >100) and show no degradation of mask filtration efficiency. We also test the Chen Heng V9501 KN95 and HKYQ N95 finding no degradation of mask filtration efficiency, however even for unheated masks these scored <50 for every fit test. The heating method presented here is scalable from individual masks to over a thousand a day with a single industrial convection oven, making this method practical for local application inside health-care facilities.

Study of face mask filtration efficiency to prevent fine dust to secure people’s right to health

In this study, we evaluated the filtering effect of the fine dust mask. Our objective research has secured credibility in the private sector. The performance of domestic fine dust masks is evaluated by three dust collection efficiencies, inspiratory resistance, and leakage rate according to KF grade in the health mask standard guidelines issued by the Ministry of Food and Drug Safety. Based on this, eight types of fine dust masks were evaluated for dust collection efficiency and face intake resistance. All masks showed good performance as the collection efficiency was 90%. The higher the KF grade, the higher the collection efficiency, but the inspiratory resistance had no correlation with the grade. According to the manufacturer's operation method, masks below the standard value may be distributed. Masks that are currently on the market have shown results that can be trusted. However, we hope that the system will be improved to validate whether the masks that meet the threshold are still being distributed.

Determining the filtration efficiency of half-face medical protection mask (N99) against viral aerosol.

Hospital-based outbreaks of severe acute respiratory syndrome (SARS) have once again highlighted the vulnerability of healthcare workers (HCWs). Use of personal respiratory protective equipment was the main method used by HCWs to avoid nosocomial transmission. This paper describes the technology used to evaluate the filtration efficiency of the half-face medical protection mask (N99), manufactured by Firmshield Biotechnology, against viral aerosol. Viral aerosol was generated and then sampled simultaneously with and without the test mask. This enables a percentage efficiency value to be calculated against test phage f2 aerosols (surrogates of viral pathogen aerosols). At the same time the mask filtration efficiency against NaCl particle aerosol was determined by use of TSI8130 equipment and face-fit factor was tested by use of TSI8020 equipment. The half-face medical protection mask (N99) evaluated by use of the viral aerosol had a filtration efficiency >99%. The mask filtration efficiency against NaCl particle aerosol was 99.634 ± 0.024% and it had a good face-fit factor. This half-face medical protection mask (N99) can protect the wearer from viral aerosol disease transmission. The test method can be used to assess filtration efficacy against viral aerosol of masks used for respiratory protection.