Quantitative Fit Testing Research Articles

SG-APSIC1119: N95 mask concordance amongst female Muslim healthcare workers undergoing mask fitting with and without tudung

Objectives: In August 2021, the Ministry of Health, Singapore revised the uniform policy in public hospitals to allow female Muslim staff, including nurses, to wear the tudung as an add-on to their uniforms. Institutions were advised that incorporation of the tudung should still align with current infection prevention guidelines. On May 2, 2021, in response to evolving evidence of SARS-CoV-2 transmission, our institution adopted the use of N95 masks for all HCWs in clinical settings. Prior to this revision in uniform policy, most female Muslim staff were mask fitted without tudungs. No existing international guidance recommends whether mask refitting of should be conducted with tudungs. As such, we looked at the N95 mask concordance for these staff undergoing mask fitting. Methods: Between November 1, 2021, and January 14, 2022, we mask fit-tested all new staff and refitted existing staff both with and without the tudung. We conducted qualitative fit-testing using their personal tudung, and we tested 2 models of N95 mask: 3MTM 1870+ and AIR+. When an HCW only passed the fitting of 1 or none of the models, additional N95 mask fit-testing was conducted with other available mask models according to our department’s existing workflow. Results: In total, 334 staff underwent N95 mask fitting. Overall, 326 (97.6%) passed with the same N95 mask models both with and without the tudung. The remaining 8 staff (2.4%) had passed 2 N95 mask models without the tudung but required a different N95 mask model while wearing the tudung. No staff required quantitative fit testing. Conclusions: N95 mask concordance for female Muslim staff undergoing fit-testing both with and without the tudung was high at 97.6%. Further evaluation of the 8 staff who did not show concordance could be retested using a quantitative fit-testing method.

A multicenter, case-control study of a novel multi-target fecal DNA test for colorectal cancer detection.

26 Background: Globally, colorectal cancer (CRC) is the fourth most frequently occurring cancer and is the second leading cause of cancer-related deaths. Early detection and diagnosis of pre-cancer lesions and CRCs at curable stages could prevent the disease or improve patient survival. Colonoscopy, the current gold-standard approach for CRC screening, is an invasive procedure, and novel non-invasive alternatives are needed. Methods: In present study, we developed a novel multi-target fecal DNA based assay, which integrates detection of two stool DNA (sDNA) methylation markers by quantitative methylation-specific PCR (qMSP) and immunochemical fecal occult blood test. We performed a multi-center case-control study to validate the diagnostic performance of this novel multi-target assay. Thus far, we collected stool specimens from a total of 784 subjects including CRC, advanced adenoma, nonadvanced neoplasms and individuals with negative findings on colonoscopy from six sites across China. All participants underwent colonoscopy; the stool specimens were tested with the multi-target fecal DNA test as well as a quantitative FIT test (OC FIT-CHEK, Eiken) in parallel in order to perform head-to-head comparison of the test performance of both assays. Results: The multi-target fecal DNA test demonstrated a higher sensitivity (96.1%) than FIT (85.3%) for CRCs (n=204). Meanwhile, 20 of 39 (51.3%) patients with advanced adenoma tested positive by the fecal DNA test, which was remarkably superior to FIT (7 of 39 tested positive, 17.9%). Among 541 participants with nonadvanced neoplasms or negative findings on colonoscopy, the specificity of the DNA test was 86.9%, compared with a specificity of 93.1% achieved by FIT. Within the control group, the DNA test and FIT yielded a specificity of 90.5% and 94.9% respectively for individuals with negative results on colonoscopy. Conclusions: The novel multi-target fecal DNA test exhibited notably superior sensitivity for both CRC and advanced adenoma cases than the commercially quantitative FIT test, while sacrificing some specificity. Our results suggest that this novel multi-target fecal based test may be used as an effective tool for early detection and pre-screening of CRC. Prospective study will be conducted to further evaluate the clinical performance and cost-effectiveness of this assay.

A randomised crossover trial of two flat-fold cup respirators: BYD DE2322 N95 versus Care Essentials MSK-002 P2.

The use of respiratory protection remains important in protecting health care workers from airborne pathogens such as viruses. Respirator supply is constantly changing with new models regularly becoming available. Health services should consider a broad range of factors when procuring respirators, including the results of quantitative fit testing in a representative sample of the workforce. Subjective comfort factors and compatibility with a variety of workplace tasks, such as suitability for staff use near magnetic resonance imaging (MRI) environments where relevant, should also be considered. This article compares the quantitative fit factors and user assessments for two styles of flat-fold cup respirators, Care Essentials (CE) MSK-002 P2 and BYD DE2322 N95. Quantitative fit tests (QNFT) were performed on 300 participants on each model of respirator in this randomised crossover trial. Participants then completed a questionnaire on their assessments of each respirator. The Care Essentials MSK-002 had a significantly higher quantitative fit test pass rate than the BYD DE2322 (57% vs 18%, p<0.001). There was no concordance between fit test pass rates for each model. Additionally, the Care Essentials MSK-002 achieved significantly higher scores on each of the responses in the subjective usability survey. It is recommended that the Care Essentials MSK-002 be made available for health care use due to higher QNFT pass rates, higher subjective usability assessment scores, plus its potential for use in MRI environments when compared to the BYD DE2322.

Protocol of a prospective comprehensive evaluation of an elastic band beard cover for filtering facepiece respirators in healthcare.

Individuals who are unable to be clean shaven for religious, medical or cultural reasons are unable to wear a filtering facepiece respirator (FFR), as the respirator cannot provide adequate protection against aerosol-transmissible diseases. There is currently a paucity of validated techniques to ensure the safe inclusion of bearded healthcare workers in the pandemic workforce. We propose to undertake a healthcare-based multi-modal evaluation study on the elastic band beard cover for FFR technique, examining the quantitative fit test (QNFT) results, usability and skill level of participants with repeated assessments over time. This is a prospective study conducted through the Respiratory Protection Program at the Royal Melbourne Hospital. Healthcare workers are invited to participate if they require respiratory protection and cannot shave for religious, cultural or medical reasons. An online education package on the use of respiratory protective equipment and the elastic band beard cover for FFR technique is provided. This is followed by a face-to-face session, where the participant will receive: one-on-one training; undergo a skill assessment on their donning, doffing and user seal check techniques; complete QNFTs and a usability survey. Participants will be invited to repeat the assessment within 3 months of the first session and at 12 months. This study involves multimodal and repeated assessments of an elastic band beard cover for FFRs. The findings of this study will provide information on: whether this simple technique can provide safe, consistent and effective respiratory protection; whether it will interfere with occupational activities; and whether it is comfortable and tolerable for the duration of wear. This is of significant importance to the health workforce around the world, who cannot shave but require access to respiratory protective equipment during the COVID-19 pandemic.

Striving to be the fittest: quantitative P2/N95 respirator fit test results among hospital staff during the COVID-19 pandemic.

To provide fit rates for specific P2/N95 respirators and compare these results by age, sex, clean-shaven status, and fit tester experience. Exploratory audit involving secondary analysis of existing quantitative fit testing data. In response to the COVID-19 pandemic, healthcare services across Australia implemented respiratory protection protocols. This study details healthcare workers' (HCWs) fit testing results from a large Victorian public health service. Fit-tested employees of a large tertiary public health network. Fit rates for ten individual P2/N95 respirators were calculated, and the effect of age, sex, clean-shaven status, and fit tester experience was examined via logistic regression. 4593 employees were included, with 97.98% successfully fitting at least one respirator. Males were found to have significantly increased odds of achieving fit success compared to females (OR 11.61 95%CI 1.60-84.10). Fit rates dropped by 4% with each 1-year age increase (OR 0.96 95%CI 0.94-0.98). Clean-shaven individuals were also more likely to achieve a fit compared to non-clean-shaved individuals (OR 79.23 95%CI 10.21-614.62). More experienced fit testers also yielded significantly higher fit rates (OR 3.95, 95%CI 2.34-6.67). 98% of staff achieved a successful fitting of at least one respirator, with three-panel flat fold models (Industree Trident, 3M Aura 9320A+, and 3M Aura 1870+) performing the most consistently. An individual's ability to achieve a successful fit was associated with; male sex, younger age, clean-shaven status, and fit tester experience.

Two masks can be worse than one: N95 respirator failure caused by an overlying face mask.

We have demonstrated the effect of covering an N95 filtering facepiece respirator (FFR) with an overlying face mask. In total, 100 participants successfully completed quantitative fit testing wearing a 3M 1870+ FFR. Among them, 13 (13%; 95% CI, 7%-22%) failed subsequent fit testing when simultaneously wearing a Halyard 47117 procedural mask over the FFR.

Comparisons of Fit Factors Between Two Quantitative Fit Testers (PortaCount vs. MT)

This study evaluated the consistency between two quantitative fit test devices with different methods of ambient aerosol counting. Three types of respirators (N95, half mask, and full facepiece) were worn by 50 participants (male, n = 25; female, n = 25), PortaCount (Pro+ 8038) and MT (05U) were connected to one probe to one mask, and fit factors (FFs) were measured simultaneously with the original and modified protocols. As a result of comparing MT FFs with PortaCount FFs as references and by applying for the pass/fail criteria (FF = 100), the consistency between the two devices for half masks and full facepieces was very high. N95 was somewhat weaker than the two type of respirators in the consistency; however, the correlation between the two devices was very strong (p < 0.0001). The results showed that an FF of 100 as measured by PortaCount was likely to be measured as 75 by the MT. Therefore, when performing the fit test for N95 using the MT and pass level of FF 100, a certain level of adjustment is necessary, whether end-user or putting a scaling factor by manufacturer.

Optimizing twin sampling tube stabilization improves quantitative fit test results for flat-fold duckbill filtering facepiece respirators

When performing quantitative fit testing (QNFT) on filtering facepiece respirators using an ambient aerosol technique, a twin sampling tube is connected between the condensation nuclei count machine and the probed respirator. To achieve high quality and repeatable QNFT results, robust sampling tube stabilization is required. In this prospective randomized crossover study, conducted in December 2021 to February 2022, we compared the commonly used hand-hold technique with the manufacturer-recommended lanyard technique in stabilizing the sampling tube during QNFT on a Halyard N95 respirator. Outcomes included QNFT pass rates, overall and individual fit factors, and concordance between the two techniques. A total of 228 out of 316 participants (72.2%) passed the QNFT with the hand-hold technique, compared to the lanyard technique (166/316, 52%, P < .001). The most significant drop in the fit factors with the lanyard technique occurred during head movement side-to-side and up-and-down. The concordance between the 2 techniques was fair (Kappa coefficient=0.39). Our study demonstrates that the method of sampling tube stabilization during QNFT has a significant impact on fit test pass rates, with a potential for false negative fit tests due to inadequate tube stabilization. Further research is required to examine the generalizability of these results to other respirators and fit testing apparatuses.

224 Variable NIOSH Quantitative Fit Testing Failure Rates of Reused and Sterilized "Duckbill" Type N95 Masks

In response to worldwide shortages of N95 masks during the SARS-CoV2 pandemic, the Centers for Disease Control and Prevention (CDC) has highlighted various conservation and reuse strategies including isolation and vaporized hydrogen peroxide but with limitations of “safe” reuse of N95 masks up to five times. The aim of this project was to evaluate the results of NIOSH quantitative fit testing after five trials of donning on a specific manufacturer’s “duckbill” type N95 masks with/without repeated sterilization using vaporized hydrogen peroxide.

Aerosolized Hydrogen Peroxide Decontamination of N95 Respirators, with Fit-Testing and Viral Inactivation, Demonstrates Feasibility for Reuse during the COVID-19 Pandemic.

ABSTRACTIn response to the demand for N95 respirators by health care workers during the COVID-19 pandemic, we evaluated decontamination of N95 respirators using an aerosolized hydrogen peroxide (aHP) system. This system is designed to dispense a consistent atomized spray of aerosolized, 7% hydrogen peroxide (H2O2) solution over a treatment cycle. Multiple N95 respirator models were subjected to 10 or more cycles of respirator decontamination, with a select number periodically assessed for qualitative and quantitative fit testing. In parallel, we assessed the ability of aHP treatment to inactivate multiple viruses absorbed onto respirators, including phi6 bacteriophage, herpes simplex virus 1 (HSV-1), coxsackievirus B3 (CVB3), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For pathogens transmitted via respiratory droplets and aerosols, it is critical to address respirator safety for reuse. This study provided experimental validation of an aHP treatment process that decontaminates the respirators while maintaining N95 function. External National Institute for Occupational Safety & Health (NIOSH) certification verified respirator structural integrity and filtration efficiency after 10 rounds of aHP treatment. Virus inactivation by aHP was comparable to the decontamination of commercial spore-based biological indicators. These data demonstrate that the aHP process is effective, with successful fit-testing of respirators after multiple aHP cycles, effective decontamination of multiple virus species, including SARS-CoV-2, successful decontamination of bacterial spores, and filtration efficiency maintained at or greater than 95%. While this study did not include extended or clinical use of N95 respirators between aHP cycles, these data provide proof of concept for aHP decontamination of N95 respirators before reuse in a crisis-capacity scenario.IMPORTANCE The COVID-19 pandemic led to unprecedented pressure on health care and research facilities to provide personal protective equipment. The respiratory nature of the SARS-CoV2 pathogen makes respirator facepieces a critical protective measure to limit inhalation of this virus. While respirator facepieces were designed for single use and disposal, the pandemic increased overall demand for N95 respirators, and corresponding manufacturing and supply chain limitations necessitated the safe reuse of respirators when necessary. In this study, we repurposed an aerosolized hydrogen peroxide (aHP) system that is regularly utilized to decontaminate materials in a biosafety level 3 (BSL3) facility, to develop a method for decontamination of N95 respirators. Results from viral inactivation, biological indicators, respirator fit testing, and filtration efficiency testing all indicated that the process was effective at rendering N95 respirators safe for reuse. This proof-of-concept study establishes baseline data for future testing of aHP in crisis-capacity respirator-reuse scenarios.

Assessing the Fit of N95 Filtering Facepiece Respirators Fitted with an Ear Loop Strap System: A Pilot Study.

Throughout the COVID-19 pandemic, hundreds of millions of people worldwide have become new users of respiratory protective devices. Facemasks and KN95 respirators utilizing an ear loop straps system (ELSS) have recently become popular among occupational and non-occupational populations. Part of this popularity is due to the ease of wearability as compared with traditional devices utilizing two headbands, one worn over the head and the other behind the neck—a universal strap system used in NIOSH-certified N95 filtering facepiece respirators (FFRs). Some users convert the two-strap configuration to an adjustable ELSS. The first objective of this pilot study was to quantitatively characterize how such a conversion impacts the respirator fit. Additionally, a novel faceseal (NFS) technology, which has been previously demonstrated to enhance the fit of N95 FFRs, was deployed to modify the ELSS-converted N95 FFRs. The second objective of this study was to quantify the fit improvement that results from adding the NFS to the ELSS. The study was conducted by performing the Occupational Safety and Health Administration (OSHA)-approved quantitative fit testing (QNFT) on 16 human subjects featuring different facial shapes and dimensions. Three models of cup-shaped N95 FFRs were tested in three versions: the standard version with manufacturer’s strap system, the ELSS-converted, and the ELSS-converted version modified by adding the NFS. QNFT demonstrated that the fit of an N95 FFR featuring the traditional/standard headbands strap system is negatively impacted when this system is converted to an ELSS. The fit of an ELSS-converted respirator can be significantly improved by the addition of the NFS. We found that the FFR model and the strap system version are significant factors affecting the QNFT-determined respirator fit factor (FF), as well as the OSHA QNFT pass rate (FF ≥100). The findings suggest that the current NFS, if further improved, has a potential for developing a ‘universally fitting’ ELSS-equipped N95 FFR that can be used by the general public, the vast majority of whom do not have access to OSHA fit requirements.

Respiratory protection preparedness in critical care healthcare workers: An observational audit of facial hair at a major tertiary hospital in Australia.

Facial hair under a tight fitting P2/N95 respirator diminishes respiratory protection. There is limited guidance with respect to the threshold to be clean shaven in readiness to wear N95 respirators. We performed a cross sectional audit in late August 2021 to observe whether staff had facial hair that could decrease respiratory protection of tight fitting respirators. The audit was conducted in three critical care areas at a major tertiary public hospital in Australia during a period of moderate-to-high community prevalence of COVID-19. All staff observed had previously successfully completed quantitative fit testing with a clean shaven face in the preceding 12 months. 110 consecutive male critical care staff were observed including thirty staff who were required to wear a N95/P2 respirator at the time. Forty - five percent of male staff observed were not clean shaven in the face seal zone of their respirators. The readiness to wear a tight-fitting respirator and hence the need to be clean shaven, should be guided by both state and local COVID-19 risk ratings, as well as the specific respiratory biohazard risks present in the clinical area at that time. During periods of significant community transmission of COVID-19, critical care clinical staff should be clean shaven, so they are fit-for-purpose and ready to wear a tight fitting respirator at short notice. Respiratory protection preparedness in critical care healthcare workers: An observational audit of facial hair at a major tertiary hospital in Australia.

The effect of ethanol immersion on fit performance and comfort of a fit tested reusable mask

Reusable high-filtration mask could be a solution for the global demand of disposable N95 and the environmental problems caused during a pandemic. We evaluated the effect of ethanol cleaning on the fit performance and comfort rating of Totobobo Masks, a reusable high-filtration mask. Healthy volunteers underwent quantitative fit testing with the Totobobo mask using a PortaCount Plus respirator fit tester. Fit factor ≥100 was considered adequate fit. Masks were then cleaned in 70% ethanol and air drying. Volunteers underwent a second and third fit test after each 15 cycles of ethanol cleaning. The proportion of adequate fit for Totobobo masks and overall fit factor were compared before and after each clean. Forty nine participants were recruited, of which 22/49 (44.9%) achieved adequate fit with Totobobo mask on the first fit test. Subsequently, 17/22 (77%) and 9/17 (53%) participants achieved adequate fit during the second and third fit tests, respectively. Proportion of adequate fit was similar before and after the first 15 cycles of ethanol cleaning ( p = .063) but lower after the second 15 cycles of ethanol cleaning ( p = .008). Fit factor was similar between the first and second fit tests ( p = 0 .808) and the second and third fit tests ( p = .125). Twenty out of 22 rated the Totobobo mask more comfortable than commercially available N95 masks. All participants rated the comfort level as either better or similar before and after cleaning. There is no significant drop in fit performance and comfort of Totobobo mask with up to 15 cycles of cleaning with 70% ethanol.

Under-mask beard covers achieve an adequate seal with tight-fitting disposable respirators using quantitative fit testing

Tight-fitting respirators are a critical component of respiratory protection against airborne diseases for health workers. However, they are not recommended for health workers with facial hair. Some health workers are unable to shave for religious or medical reasons. Under-mask beard covers have been proposed as a solution to allow health workers with facial hair to wear tight-fitting respirators. However, studies to date have been limited by their predominant reliance on qualitative rather than quantitative fit testing techniques. To assess the efficacy of under-mask beard covers in achieving an adequate seal with tight-fitting disposable P2/N95 respirators using quantitative fit testing. Bearded adult males underwent quantitative fit testing with an under-mask beard cover using either a TSI PortaCount Respirator Fit Tester 8038 or an AccuFit 9000 PRO fit testing device on up to five disposable P2/N95 respirators (3M 1860, 3M 1870+, BYD N95 Healthcare Particulate Respirator, BSN Medical ProShield N-95 Medium and Trident RTCFFP2). The primary outcome was the proportion of subjects that passed or failed quantitative fit testing with an under-mask beard cover. Thirty subjects were assessed; of these, 24 (80%) passed quantitative fit testing with at least one tight-fitting P2/N95 disposable respirator. Among these subjects, the median best-achieved fit factor was 200 (interquartile range 178-200). None of the subjects had an adverse reaction to the under-mask beard cover. The under-mask beard cover technique may be used to achieve a satisfactory seal with tight-fitting P2/N95 respirators in health workers with facial hair who cannot shave.

N95 respirators: quantitative fit test pass rates and usability and comfort assessment by health care workers.

ObjectivesTo compare the performance of four N95 respirator types with respect to quantitative fit test pass rate and health care worker‐rated usability and comfort.Design, setting, participantsHealth care workers who participated in the respiratory protection program at the Royal Melbourne Hospital, 1 October 2020 – 31 May 2021. Participants underwent quantitative N95 respirator fit testing (at least three of four types: semi‐rigid cup, flat‐fold cup, duckbill, and three‐panel flat‐fold types), and were invited to complete an online usability and comfort assessment for respirators for which their fit test results were passes.Main outcome measuresFit test pass rate, and user‐rated overall comfort and assessment ratings (five‐point Likert scales), by N95 respirator type.ResultsA total of 2161 health care workers underwent quantitative fit testing (women, 1586 [73.4%]; nurses, 1271 [58.8%]). The overall fit test pass rates were 65.0% for the semi‐rigid cup respirators (1029/1583 tests), 32.4% for the flat‐fold respirator (660/2035 tests), 59.2% for the duckbill respirators (2005/3387 tests), and 96.4% for the three‐panel flat‐fold respirator (1876/1946 tests). 378 health care workers completed the comfort and usability survey. Overall comfort and assessment ratings each differed by respirator group (P < 0.001); the median overall comfort (4; IQR, 3–4) and overall assessment values (4; IQR, 3–5) were highest for the three‐panel flat‐fold respirator and lowest for the semi‐rigid cup respirators (comfort: 2 [IQR, 1–3]; assessment: 2 [IQR, 2–3]).ConclusionsThe three‐panel flat‐fold N95 respirator outperformed the three alternative types with regard to fit test pass rate and user‐rated comfort and usability. To maximise respiratory protection for health care workers, these factors should be considered when making respirator procurement decisions.

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.

Randomized crossover study comparing quantitative fit tests between Trident™ and 3M™ Aura™ N95/P2 respirators.

Various styles of N95/P2 filtering facepiece respirators (FFRs) have been used by Australian healthcare workers (HCWs) during the COVID-19 pandemic. This is usually driven by the national stockpile availability. Many studies demonstrate three-panel flat-fold N95/P2 FFRs have higher quantitative fit test (QNFT) pass rates than other FFR styles. This prospective randomized crossover study utilized QNFT to evaluate the performance of the new three-panel flat-fold FFR, the Trident™ P2 respirator compared to the previously most effective model, the 3M™ Aura™ 9320A+N95 respirator. We recruited 500 participants who completed online training and QNFT on both respirators. The order of the respirator being examined first was randomly allocated. The primary outcome was the QNFT pass rate. Secondary outcomes included the overall fit factor, the individual fit factor for each exercise, and the first-attempt QNFT pass rate. We found that both the overall and first-attempt QNFT pass rates of the Trident P2 respirator were significantly higher than the 3M Aura (99.2% vs 92.6%, p<0.001; and 92.6% vs 76.4%, p<0.001 respectively). The overall fit factor and the individual fit factor were also significantly higher for the Trident FFR than the 3M Aura. This study is the first to report hospital-based QNFT results of the Trident FFR, demonstrating very high first-time and overall pass rates. Our findings are consistent with previous research showing very high QNFT pass rates with three-panel flat-fold FFRs. These findings are important for pandemic preparedness with respect to the stockpiling and safe utilization of N95/P2 respirators.

HALO CleanSpace PAPR evaluation: Communication, respiratory protection, and usability.

To evaluate a relatively new half-face-piece powered air-purifying respirator (PAPR) device called the HALO (CleanSpace). We assessed its communication performance, its degree of respiratory protection, and its usability and comfort level. This simulation study was conducted at the simulation center of the Royal Melbourne Hospital. In total, 8 voluntary healthcare workers participated in the study: 4 women and 4 men comprising 3 nursing staff and 5 medical staff. We performed the modified rhyme test, outlined by the National Institute for Occupational Safety and Health (NIOSH), for the communication assessment. We conducted quantitative fit test and simulated workplace protection factor studies to assess the degree of respiratory protection for participants at rest, during, and immediately after performing chest compression. We also invited the participants to complete a usability and comfort survey. The HALO PAPR met the NIOSH minimum standard for speech intelligibility, which was significantly improved with the addition of wireless communication headsets. The HALO provided consistent and adequate level of respiratory protection at rest, during and after chest compression regardless of the device power mode. It was rated favorably for its usability and comfort. However, participants criticized doffing difficulty and perceived communication interference. The HALO device can be considered as an alternative to a filtering face-piece respirator. Thorough doffing training and mitigation planning to improve the device communication performance are recommended. Further research is required to examine its clinical outcomes and barriers that may potentially affect patient or healthcare worker safety.

Fitted filtration efficiency and breathability of 2-ply cotton masks: Identification of cotton consumer categories acceptable for home-made cloth mask construction.

The objective of this study was to characterize commercially-available cotton fabrics to determine their suitability as materials for construction of cloth masks for personal and public use to reduce infectious disease spread. The study focused on cottons because of their widespread availability, moderate performance and they are recommended for inclusion in home-made masks by international health authorities. Fifty-two cottons were analyzed by electron microscopy to determine fabric characteristics and fabric weights. Sixteen fabrics were selected to test for breathability and to construct 2-ply cotton masks of a standard design to use in quantitative fit testing on a human participant. Cotton mask fitted filtration efficiencies (FFEs) for 0.02–1 μm ambient and aerosolized sodium chloride particles ranged from 40 to 66% compared with the mean medical mask FFE of 55±2%. Pressure differentials across 2-ply materials ranged from 0.57 to > 12 mm H2O/cm2 on samples of equal surface area with 6 of 16 materials exceeding the recommended medical mask limit. Models were calibrated to predict 2-ply cotton mask FFEs and differential pressures for each fabric based on pore characteristics and fabric weight. Models indicated cotton fabrics from 6 of 9 consumer categories can produce cloth masks with adequate breathability and FFEs equivalent to a medical mask: T-shirt, fashion fabric, mass-market quilting cotton, home décor fabric, bed sheets and high-quality quilting cotton. Masks from one cloth mask and the medical mask were re-tested with a mask fitter to distinguish filtration from leakage. The fabric and medical masks had 3.7% and 41.8% leakage, respectively. These results indicate a well fitted 2-ply cotton mask with overhead ties can perform similarly to a disposable 3-ply medical mask on ear loops due primarily to the superior fit of the cloth mask which compensates for its lower material filtration efficiency.

Development and application of a modified procedure for quantitative fit testing of disposable masks and respirators

In this study, a modified procedure for quantitative fit testing of disposable masks and respirators using condensation nuclei counting was developed and applied. The procedure permits disposable masks and respirators to be initially tested and retested multiple times after use. Different types of masks and respirators were tested over time and quantitative results were obtained. It was found that after multiple testing that the N95 respirator passed the testing requirements with a fit factor above 100, the KN95 respirator did not perform satisfactorily in the tests, and the disposable masks did not reach fit factors above 4 or 7. The results in this study provided relevant information toward use, reuse, and testing of disposable masks and respirators, particularly relevant during the COVID pandemic when access to N95 respirators was limited.