Evaluation of the benefit of the user seal check on N95 filtering facepiece respirator fit

Infra-Red Imaging to Detect Respirator Leak in Healthcare Workers During Fit-Testing Clinic

OBJECTIVE

This study addressed the problem of objectively detecting leaks in P2 respirators at point of use, an essential component for healthcare workers' protection. To achieve this, we explored the use of infra-red (IR) imaging combined with machine learning algorithms on the thermal gradient across the respirator during inhalation.

RESULTS

The study achieved high accuracy in predicting pass or fail outcomes of quantitative fit tests for flat-fold P2 FFRs. The IR imaging methods surpassed the limitations of self fit-checking.

CONCLUSIONS

The integration of machine learning and IR imaging on the respirator itself demonstrates promise as a more reliable alternative for ensuring the proper fit of P2 respirators. This innovative approach opens new avenues for technology application in occupational hygiene and emphasizes the need for further validation across diverse respirator styles.

SIGNIFICANCE STATEMENT

Our novel approach leveraging infra-red imaging and machine learning to detect P2 respirator leaks represents a critical advancement in occupational safety and healthcare workers' protection.

Effectiveness of fit testing versus fit checking for healthcare workers respiratory protective equipment: A systematic review

Objectives

Respiratory protection is critical in healthcare to minimise the risk of airborne infections for healthcare workers (HCWs). It emphasizes the use of proper fitting of particulate filter respirators and equivalent respiratory protective equipment (RPE) to ensure a good facial seal. The systematic review aimed to compare the effectiveness of fit testing and fit checking for HCWs' respiratory protective equipment.

Methods

A systematic review of the literature exploring RPE for HCWs to determine the effectiveness of fit-testing versus fit-checking from January 2003 to April 2022 was identified using CINAHL Complete via EBSCO Host, Cochrane Library, EMBASE, PubMed, and MEDLINE via Ovid electronic databases, and grey literature. The study protocol was registered with PROSPERO (registration number: CRD42020213968).

Results

Of the 561 articles identified in the search, 25 articles (22 quantitative studies and three guidelines) were included in this review. Overall, these studies suggest fit-testing as a method that is more effective, widely adopted, and reliable in assessing the effectiveness of RPE; however, a respiratory program should include both fit-testing and fit-checking to maximise effectiveness of the RPE. The COVID-19 epidemic highlighted a lack of knowledge among HCWs regarding fit-checking and fit-testing, and relevant education increased the effectiveness of respiratory equipment protection.

Conclusion

It is imperative that both fit-testing and fit-checking is implemented in order to ensure HCW safety. It is recommended to integrate education, fit-testing and fit-checking into a comprehensive respiratory protective program run by trained fit-testers. There is also a need for practical testing methods that incorporate the clinical environment.

Overview of tight fit and infection prevention benefits of respirators (filtering face pieces)

Regulations for measures to protect against SARS-CoV-2 transmission vary widely around the world, with very strict regulations in Germany where respirators (filtering face piece FFP2 or comparable) are often mandatory. The efficiency of respirators, however, depends essentially on the tight facial fit avoiding the bypass of contaminated air via gaps between mask and wearer's face. The facial fit can be verified in a fit test. The aim of this review was to describe the quantitative fit test results depending on the respirator designs. A literature search revealed 29 suitable studies. Of all respirators with circumferential head straps, three-panel folded dome-shaped respirators showed the best fit (80.8% of 4625 fit tests passed), followed by rigid-dome-shaped respirators (72.4% of 8234 fit tests passed), duckbill-shaped respirators (31.6% of 2120 fit tests passed), and coffee-filter-shaped respirators (30.9% of 3392 fit tests passed). Respirators with ear loops showed very poor tight fit (3.6% of 222 fit tests passed). In four randomized control trials, single-use respirators were not shown to be superior to surgical masks for the prevention of laboratory-confirmed viral respiratory infections, even when adjusted with a fit test. Therefore, we consider the mandatory use of respirators to be disproportionate and not supported by evidence. Further evidence should be generated, in which scenarios respirators might provide an effective benefit as part of occupational health and safety. For situations with confirmed benefits, only high-quality disposable respirators with head straps or respiratory protective equipment of higher protective levels should be used.

A critical review on the role of leakages in the facemask protection against SARS-CoV-2 infection with consideration of vaccination and virus variants

The protection provided by facemasks has been extensively investigated since the beginning of the SARS-CoV-2 outbreak, focusing mostly on the filtration efficiency of filter media for filtering face pieces (FFP), surgical masks, and cloth masks. However, faceseal leakage is a major contributor to the number of potentially infectious airborne droplets entering the respiratory system of a susceptible individual. The identification of leaking spots and the quantification of leaking flows are crucial to estimate the protection provided by facemasks. This study presents a critical review on the measurement and calculation of facemask leakages and a quantitative analysis of their role in the risk of SARS-CoV-2 infection. It shows that the pairing between the mask dimensions and the wearer's face is essential to improve protection efficiency, especially for FFP2 masks, and summarizes the most common leaking spots at the interface between the mask and the wearer's face. Leakage is a crucial factor in the calculation of the protection provided by facemasks and outweighs the filtration performances. The fit factors measured among mask users were summarized for different types of face protection. The reviewed data were integrated into a computational model to compare the mitigation impact of facemasks with vaccination with consideration of new variants of SARS-CoV-2. Combining a high adoption rate of facemasks and a high vaccination rate is crucial to efficiently control the spread of highly infectious variants.

P2/N95 filtering facepiece respirators: Results of a large-scale quantitative mask fit testing program in Australian health care workers

Background

In response to the COVID-19 pandemic, 6,287 Australian health care workers (HCWs) were fit tested to N95 filtering facepiece respirators (FFRs). This study determined how readily HCWs were fitted to 8 FFRs and how age and sex influenced testing.

Methods

HCWs were fit tested following the quantitative OSHA protocol. After bivariate analysis, a logistic regression model assessed the effect of FFR model, HCW age and sex on fit test results.

Results

Of 4,198 female and 2,089 male HCWs tested, 93.3% were successfully fitted. Fifty-five percent passed the first FFR, 21% required 2 and 23% required testing on 3 or more models. Males were 15% less likely to pass compared to females (P < .001). Individuals aged 18-29 were significantly more likely to pass compared to colleagues aged 30-59. Cup-style 3M 1860S was the most suitable model (95% CI: 1.94, 2.54) while the duckbill BSN TN01-11 was most likely to fail (95% CI: 0.11, 0.15).

Conclusions

Current N95 FFRs exhibit suboptimal fit such that a large proportion (45%) of HCWs require testing on multiple models. Older age and male sex were associated with significantly higher fit failure rates. QNFT programs should consider HCW characteristics like sex, age, racial and facial anthropometric measurements to improve the protection of the health workforce.

Personal Interventions to Reduce Exposure to Outdoor Air Pollution

Unhealthy levels of air pollution are breathed by billions of people worldwide, and air pollution is the leading environmental cause of death and disability globally. Efforts to reduce air pollution at its many sources have had limited success, and in many areas of the world, poor air quality continues to worsen. Personal interventions to reduce exposure to air pollution include avoiding sources, staying indoors, filtering indoor air, using face masks, and limiting physical activity when and where air pollution levels are elevated. The effectiveness of these interventions varies widely with circumstances and conditions of use. Compared with upstream reduction or control of emissions, personal interventions place burdens and risk of adverse unintended consequences on individuals. We review evidence regarding the balance of benefits and potential harms of personal interventions for reducing exposure to outdoor air pollution, which merit careful consideration before making public health recommendations with regard to who should use personal interventions and where, when, and how they should be used. Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Quantitative fit testing of filtering face-piece respirators during the COVID-19 pandemic reveals anthropometric deficits in most respirators available in Iran

PURPOSE

Frontline health care workers (HCWs) must wear a standard N95 or FFP2 respirator during worldwide pandemics of respiratory diseases including COVID-19 to protect against airborne infectious pathogens when performing care activities. This study aimed to quantitatively investigate the fit of most of the common FFRs used during the COVID-19 pandemic in Iran.

METHODS

A total of 37 volunteers were fit tested in 20 selected FFRs in a randomized order. The selected FFRs were underwent quantitative fit testing by PortaCount® model 8038. To determine the effects of face sizes on respirator fit, the participants' facial dimensions were measured using a digital caliper.

RESULTS

The rate of passing fit tests for the studied FFRs were surprisingly low with 11 out of 20 FFRs having less than 10% passing fit tests and the best performers having only 43% and 27% passing fit tests (brands 2 and 20, respectively). Cup-shaped respirators provided significantly greater fit than the vertical flat-fold ones (p < 0.001). A significantly different FFs were found among the respirator brands (F = 13.60, p < 0.001).

CONCLUSION

Overall, unacceptably low fit factors were obtained from the studied FFRs. The main reasons for this are suspected to single size and style for each studied FFR. It confirms the importance and requirement of the proper respirator selection in that way fitted optimally into facial dimensions, appropriate usage, and properly performing the fit testing procedure. A unique fit test panel should be developed to guide respirator wearers in selecting the appropriate FFR for their specific face sizes.

The Importance of Proper Use of N95 Respirators by Health-Care Workers

The novel coronavirus causing the COVID-19 pandemic is spread by respiratory transmission through droplets and contact. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend the use of personal protective equipment (PPE) including a gown, gloves, and a surgical mask or N95 respirator plus a face shield and/or goggles for health-care workers who are in direct contact with COVID-19 patients. A study in China by Wang found that health-care workers on the front line of disease treatment had inadequate training in the use of PPE, particularly for respiratory infectious diseases. Instruction in the proper use of N95 respirators, with an emphasis on performing user seal checks, as well as donning and doffing, is recommended for everyone caring for COVID-19 patients.

Training through fit test and its role in knowledge, attitude and performance of workers regarding respiratory protective equipment: a case study in a petrochemical company

Background. Providing workers with respiratory protective equipment (RPE) is not enough to protect them. RPE should be selected correctly, worn properly and fitted adequately. The aim of the present study was to assess the effect of training through fit test (TTFT) on knowledge, attitude and performance (KAP) of workers regarding a respiratory protection program. Methods. This cross-sectional study was conducted on 110 respirator users in a petrochemical wastewater treatment plant. A structured questionnaire was developed to assess the KAP of workers before any intervention. After that, all participants were trained with a 15-min video-based training intervention and then the qualitative fit test was performed. Participants who failed in the fit test were retrained and the test was repeated. To assess the effect of TTFT, the KAP questionnaire was completed after 3 months. SPSS version 22.0 was used to analyze data. Results. There was a significant difference between knowledge, attitude and some of the unsafe behavior before and after TTFT. There was no person with a poor or very poor knowledge status after TTFT. Conclusion. TTFT could improve some unsafe behaviors associated with the user seal check. Moreover, TTFT could be considered an opportunity to improve workers' KAP regarding RPE.

Guidelines for Frontline Health Care Staff Safety for COVID-19

This document establishes safety guidelines for physicians, nurses, and allied health care and facility staff who may be exposed to patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a health care facility. SARS-CoV-2 infection is highly contagious and places health care workers at risk for infection resulting in coronavirus disease (COVID-19). Physicians, nurses, and allied health care and facility staff in all frontline environments must be provided and utilize necessary personal protective equipment (PPE). It is important that health care staff adopt a universal set of guidelines in which to conduct themselves in order to minimize infection with the SARS-CoV-2 contagion. The establishment of these guidelines is necessary in this viral pandemic since such directives can create a standard of safety that is universally accepted. These guidelines establish a framework to provide consistency among health care facilities and staff from the time the staff member arrives at the health care facility until they return home. These guidelines provide a practical description of the minimum necessary protection for physicians, nurses, and allied health care and facility staff against SARS-CoV-2 infection.

Evaluation of the user seal check on gross leakage detection of 3 different designs of N95 filtering facepiece respirators

Background

The use of N95 respirators prevents spread of respiratory infectious agents, but leakage hampers its protection. Manufacturers recommend a user seal check to identify on-site gross leakage. However, no empirical evidence is provided. Therefore, this study aims to examine validity of a user seal check on gross leakage detection in commonly used types of N95 respirators.

Methods

A convenience sample of 638 nursing students was recruited. On the wearing of 3 different designs of N95 respirators, namely 3M-1860s, 3M-1862, and Kimberly-Clark 46827, the standardized user seal check procedure was carried out to identify gross leakage. Repeated testing of leakage was followed by the use of a quantitative fit testing (QNFT) device in performing normal breathing and deep breathing exercises. Sensitivity, specificity, predictive values, and likelihood ratios were calculated accordingly.

Results

As indicated by QNFT, prevalence of actual gross leakage was 31.0%-39.2% with the 3M respirators and 65.4%-65.8% with the Kimberly-Clark respirator. Sensitivity and specificity of the user seal check for identifying actual gross leakage were approximately 27.7% and 75.5% for 3M-1860s, 22.1% and 80.5% for 3M-1862, and 26.9% and 80.2% for Kimberly-Clark 46827, respectively. Likelihood ratios were close to 1 (range, 0.89-1.51) for all types of respirators.

Conclusions

The results did not support user seal checks in detecting any actual gross leakage in the donning of N95 respirators. However, such a check might alert health care workers that donning a tight-fitting respirator should be performed carefully.

Respiratory protection policies and practices among the health care workforce exposed to influenza in New York State: evaluating emergency preparedness for the next pandemic

BACKGROUND

New York State hospitals are required to implement a respiratory protection program (RPP) consistent with the Occupational Safety and Health Administration respirator standard. Guidance provided during the 2009 novel H1N1 pandemic expanded on earlier recommendations, emphasizing the need to keep staff in all health care settings healthy to maintain services.

METHODS

New York State hospitals with emergency departments having more than 1,000 visits annually were invited to participate; 23 hospitals participated. Health care workers, unit managers, and hospital managers were interviewed regarding knowledge, beliefs, and practices of respiratory protection. Interviewees were observed donning and doffing an N-95 respirator as they normally would during patient care. Written RPPs for each hospital were evaluated.

RESULTS

The majority of the hospitals surveyed had implemented an RPP, although unawareness of the policies and practices, as well as inadequacies in education and training exist among health care workers.

CONCLUSION

Health care workers and other hospital employees may be unnecessarily exposed to airborne infectious diseases. Having an RPP ensures safe and effective use of N-95 respirators and will help prevent avoidable exposure to disease during a pandemic, protecting the health care workforce and patients alike.

Fitting characteristics of N95 filtering-facepiece respirators used widely in China

BACKGROUND

Millions of people rely on N95 filtering facepiece respirators to reduce the risk of airborne particles and prevent them from respiratory infections. However, there are no respirator fit testing and training regulations in China. Meanwhile, no study has been conducted to investigate the fit of various respirators. The objective of this study was to investigate whether people obtained adequate fit when wearing N95 filtering facepiece respirators (FFRs) used widely in China.

METHODS

Fifty adult participants selected using the Chinese respirator fit test panel donned 10 common models of N95 FFRs. Fit factors (FF) and inward leakage were measured using the TSI PortaCount Plus. Each subject was tested with three replications for each model. A subject was considered to pass the fit test when at least two of the three FFs were greater than 100. Two models were conducted fit tests before and after training to assess the role of training.

RESULTS

The geometric mean FFs for each model and trained subjects ranged from <10 to 74.0. The fifth percentile FFs for only two individual respirator models were greater than 10 which is the expected level of performance for FFRs. The passing rates for these two models of FFRs were 44.7% and 20.0%. The passing rates were less than 10.0% for the other eight models. There were 27 (54%) participants who passed none of the 10 FFRs. The geometric mean FFs for both models when the subjects received training (49.7 and 74.0) were significantly larger than those when the same group of subjects did not receive any training (29.0 and 30.9) (P<0.05).

CONCLUSIONS

FFRs used widely in China should be improved according to Chinese facial dimensions. Respirator users could benefit from respirator training and fit testing before using respirators.

Effect of upper strap downward displacement on n95 filtering facepiece respirator fit factors: a pilot study

Fifteen subjects underwent three replicates of quantitative respirator fit-testing with N95 filtering facepiece respirators that were donned with the upper strap high on the occiput, as per the manufacturers' donning instructions. Each fit-test was immediately followed by repeat fit-testing with the upper strap downwardly displaced to the level of the ear sulcus to determine any change in fit factors that might occur with upper strap downward slippage. A total of 35/45 (78%) initial fit-tests had a passing score (fit factor ≥ 100) with the top strap high on the occiput and 33/35 (94%) of these passed subsequent fit-testing after the top strap was displaced downward to the ear sulcus. Geometric mean fit factors for the initial passed fit-tests, and following downward strap displacement, were 217 ± 1.6 and 207 ± 1.9, respectively (p = 0.64). Downward displacement of the top strap did not significantly impact fit factors of N95 FFRs that had previously passed fit-testing.

Laboratory faceseal leakage evaluation of n95 filtering facepiece respirators against nanoparticles and "all size" particles

National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) are used for respiratory protection in some workplaces handling engineered nanomaterials. Previous NIOSH research has focused on filtration performance against nanoparticles. This article is the first NIOSH study using human test subjects to compare N95 FFR faceseal leakage (FSL) performance against nanoparticles and "all size" particles. In this study, estimates of FSL were obtained from fit factor (FF) measurements from nine test subjects who participated in previous fit-test studies. These data were analyzed to compare values obtained by: 1) using the PortaCount Plus (8020A, TSI, Inc., MN, USA) alone (measureable particle size range 20 nm to > 1,000 nm, hereby referred to as the "all size particles test"), and 2) using the PortaCount Plus with N95-Companion(TM) accessory (8095, TSI, Inc., Minn.) accessory (negatively charged particles, size range ∼40 to 60 nm, hereby referred to as the "nanoparticles test"). Log-transformed FF values were compared for the "all size particles test" and "nanoparticles test" using one-way analysis of variance tests (significant at P < 0.05). For individual FFR models, geometric mean (GM) FF using the "nanoparticles test" was the same or higher than the GM FFs using "all size particles test." For all three FFR models combined, GM FF using the "nanoparticles test" was significantly higher than the GM FF using "all size particles test" (P < 0.05). These data suggest that FSL for negatively charged ∼40-60 nm nanoparticles is not greater than the FSL for the larger distribution of charged and uncharged 20 to > 1,000 nm particles.