Fit-testing of respiratory protective equipment in the UK during the initial response to the COVID-19 pandemic

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

Objective

To provide fit rates for specific P2/N95 respirators and compare these results by age, sex, clean-shaven status, and fit tester experience.

Design

Exploratory audit involving secondary analysis of existing quantitative fit testing data.

Setting

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.

Participants

Fit-tested employees of a large tertiary public health network.

Methods

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.

Results

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).

Conclusions

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.

The effect of N95 designs on respirator fit and its associations with gender and facial dimensions

This study examined the association of various brands of NIOSH-certified N95 filtering face-piece respirators (FFR) fit with facial dimensions and gender. One hundred and thirty-five participants (77 females and 58 males) were recruited from the previous facial anthropometry study among Malaysians in 2020. Quantitative respirator fit testing of six FFR were performed using the TSI Portacount Pro+ 8038 which comprised of four exercises (bending over, talking, up-down head movement, and side to side head movement). An overall fit factor (FF) of ≥ 100 was considered a pass for each FFR. Analysis was done using T-test, Pearson's correlations, and generalised linear regression. The passing rates for the six FFR were 36.3% (Cup B), 50.4% (Trifold A), 54.1% (Duckbill A), 57.0% (Cup A), 74.1% (Trifold B), and 83.7% (Duckbill B). Both Duckbill B and Trifold B had the highest passing rates for both genders. However, certain FFR models (Cup B, Trifold A, Trifold B, and Duckbill A) fit better for participants with large facial size who were mostly males, while others (Cup A and Duckbill B) specifically fit better for those with small facial size, who were mostly females. This study showed significant positive effect of nose protrusion, nasal root and subnasale-sellion and the negative effect of menton-sellion, bigonial breadth and nose breadth on fit factors of various FFR. The results of this study emphasized the importance of choosing and designing FFR based on local anthropometry data, with careful consideration on the dimensions that affect the respirator fit. Since N95 are commonly used in the healthcare settings to prevent airborne transmission, the practice of respirator fit testing and selecting N95 with high passing rates for healthcare workers need to be emphasized.

A systematic review of passing fit testing of the masks and respirators used during the COVID-19 pandemic: Part 1-quantitative fit test procedures

BACKGROUND

During respiratory infection pandemics, masks and respirators are highly sought after, especially for frontline healthcare workers and patients carrying respiratory viruses. The objective of this study was to systematically review fit test pass rates and identify factors influencing the fitting characteristics.

METHODS

Potentially relevant studies were identified using PubMed, Scopus, Web of Science, and Science Direct during the COVID-19 pandemic from February 5, 2020, to March 21, 2023. The search strategy using the following keywords was conducted: Quantitative Fit Test, Condensation Nuclei Counter, Controlled Negative Pressure, PortaCount, Sibata, Accufit, Fit, Seal, Mask, Respirator, Respiratory Protective Device, Respiratory Protective Equipment, Protective Device, Personal Protective Equipment, COVID-19, Coronavirus, and SARS-CoV-2. The quality of the included studies was also assessed using the Newcastle-Ottawa scale.

RESULTS

A total of 137 articles met the eligibility criteria. Fifty articles had a quality score of less than 7 (good quality). A total of 21 studies had a fit test pass rate of less than 50%. 26 studies on disposable respirators and 11 studies on reusable respirators had an FF of less than 50 and less than 200, respectively. The most influential factors include respirator brand/model, style, gender, ethnicity, facial dimensions, facial hair, age, reuse, extensive movement, seal check, comfort and usability assessment, and training.

CONCLUSION

37.36% of the disposable respirator studies and 43% of the reusable respirator studies did not report fit test results. 67.86% of the disposable respirator studies had a fit test pass rate greater than 50%, and 35.84% of these studies had an FF greater than 100. Also, 85.71% of the reusable respirator studies had a fit test pass rate greater than 50%, and 52.77% of these studies had an FF greater than 1000. Overall, the fit test pass rate was relatively acceptable. Newly developed or modified respirators must undergo reliable testing to ensure the protection of HCWs. Subject and respirator characteristics should be considered when implementing fit testing protocols. An optimal fit test panel should be developed prior to respirator design, certification, procurement decisions, and selection procedures.

Correlation between use of different type protective facemasks and the oral ecosystem

BACKGROUND

Spread worldwide through droplets, the Virus Sars-Cov-19 has caused a global health emergency alarm. In order to limit its spread, the use of masks has become part of the daily life of the entire population, however, little is known about its constant use and the changes generated in the oral cavity. This work aims to investigate correlations between the continuous use of masks covering the nose and mouth for 3 h and changes in the ecological factors of the oral cavity.

METHODS

34 volunteers were divided into 2 groups: wear only the filtering facepiece code 2 (FFP2) mask (Group A) and wear the FFP2 mask covered by a surgical mask (Group B). Measurement of Volatile Organic Compounds (VOCs), saliva rehydration and consistency test, collection of basal saliva and saliva stimulated with paraffin gum and mucosal swab were collected and analyzed at two times: before using the mask(s) (T0) and 3 h after continuous use of the mask(s) (T1).

RESULTS

The results indicated a significant difference between the groups, in which the basal saliva volume and pH and the peaks of VOCs increased for group B between T0 and T1. The rehydration time decreased and the volume and pH of the stimulated saliva increased, but with no significant difference between the groups. Furthermore, group B showed a significant decrease in Candida albicans Colony Forming Units (CFUs) and Total Bacterial Count (TBC) between T0 and T1.

CONCLUSION

It is concluded that the prolonged use of the FFP2 mask covered by a surgical mask can generate oral alterations in the user.

The adequacy of user seal checking for N95 respirators compared to formal fit testing: A multicentred observational study

OBJECTIVE

The objective of this study was to evaluate the adequacy of the user seal check (USC) in predicting N95 respirator fit.

DESIGN

This was a prospective, observational study conducted from May to September 2020.

SETTING

The study setting included three private intensive care units (ICUs) in Victoria, Australia.

PARTICIPANTS

ICU staff members in three private ICUs in Melbourne and regional Victoria participated in this study.

MAIN OUTCOME MEASURES

The main outcome measure is the proportion of participants who passed a USC and subsequently failed fit testing of an N95 respirator.

INTERVENTION

Three different respirators were available: two N95 respirator brands and CleanSpace HALO® powered air-purifying respirator. Participants were sequentially tested on N95 respirators followed by powered air-purifying respirators until either successful fit testing or failure of all three respirators. The first N95 tested was based on the availability on the day of testing. The primary outcome was failure rate of fit testing on the first N95 respirator type passing a USC.

RESULTS

Of 189 participants, 22 failed USC on both respirators, leaving 167 available for the primary outcome. Fifty-one of 167 (30.5%, 95% confidence interval = 23.7-38.1) failed fit testing on the first respirator type used that had passed a USC.

CONCLUSION

USC alone was inadequate in assessing N95 respirator fit and failed to detect inadequate fit in 30% of participants. Mandatory fit testing is essential to ensure adequate respiratory protection against COVID-19 and other airborne pathogens.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12620001193965.

Retrospective evaluation of factors affecting successful fit testing of respiratory protective equipment during the early phase of COVID-19

OBJECTIVES

Respiratory protective equipment is critical to protect healthcare workers from COVID-19 infection, which includes filtering facepiece respirators (FFP3). There are reports of fitting issues within healthcare workers, although the factors affecting fitting outcomes are largely unknown. This study aimed to evaluate factors affecting respirator fitting outcomes.

DESIGN

This is a retrospective evaluation study. We conducted a secondary analysis of a national database of fit testing outcomes in England between July and August 2020.

SETTINGS

The study involves National Health Service (NHS) hospitals in England.

PARTICIPANTS

A total of 9592 observations regarding fit test outcomes from 5604 healthcare workers were included in the analysis.

INTERVENTION

Fit testing of FFP3 on a cohort of healthcare workers in England, working in the NHS.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was the fit testing result, that is, pass or fail with a specific respirator. Key demographics, including age, gender, ethnicity and face measurements of 5604 healthcare workers, were used to compare fitting outcomes.

RESULTS

A total of 9592 observations from 5604 healthcare workers were included in the analysis. A mixed-effects logistic regression model was used to determine the factors which affected fit testing outcome. Results showed that males experienced a significantly (p<0.05) higher fit test success than females (OR 1.51; 95% CI 1.27 to 1.81). Those with non-white ethnicities demonstrated significantly lower odds of successful respirator fitting; black (OR 0.65; 95% CI 0.51 to 0.83), Asian (OR 0.62; 95% CI 0.52 to 0.74) and mixed (OR 0.60; 95% CI 0.45 to 0.79.

CONCLUSION

During the early phase of COVID-19, females and non-white ethnicities were less likely to have a successful respirator fitting. Further research is needed to design new respirators which provide equal opportunity for comfortable, effective fitting of these devices.

Personal protective equipment (PPE) related adverse skin reactions among healthcare workers at the main COVID-19 isolation center in Barbados

Background

The use of personal protective equipment (PPE) reduces the risk of transmission of infectious agents significantly among healthcare workers (HCWs). The study aimed to investigate the prevalence and characteristics of PPE-related adverse skin reactions among HCWs working at the main COVID-19 isolation center in Barbados.

Methods

A cross-sectional web-based online survey was conducted during April to June 2021 which recorded demographic information, details of PPE use and adverse skin reactions including severity and duration of onset of symptoms.

Results

Most of the respondents used PPE for consecutive days (77.9%), 1-6 h/day (59.2%), and more than a year (62.5%). Fewer than half of the participants (45.6%) experienced adverse skin reactions from the use of PPE. The reactions were mostly observed in the cheeks (40.4%) and nose bridges (35.6%). Females had more reactions than their male counterparts (p = 0.003). The use of N95 masks and a combination of surgical and N95 masks produced adverse effects predominantly in the ears (60%) and cheeks (56.4%). Binary logistic regression showed that female HCWs (OR = 5.720 95% CI: 1.631, 20.063), doctors (OR = 5.215 95% CI: 0.877, 31.002), and longer duration of PPE use (>1 year) (OR = 2.902 95% CI: 0.958, 8.787) caused a significantly higher prevalence of adverse skin reactions.

Conclusion

The PPE-related skin reactions were common among HCWs which mainly occurred due to prolonged use. Preventive measures inclusive of appropriate training of HCWs on the use of PPE are recommended to minimize these adverse events.

Improving the fit of filtering facepiece respirators

Aims To assess the effectiveness and acceptability of smartphone customised frame technology to improve the fit of disposable filtering facepiece class 3 (FFP3) respirators for dental staff who previously failed fit testing.Method In total, 20 volunteers who previously failed FFP3 fit testing were recruited to use smartphone technology (Bellus3D FaceApp) to have a 3D-printed bespoke face frame produced for them. They underwent qualitative fit testing with and without the frame with two freely available disposable FFP3 respirator designs (mask A: GVS F31000 Segre folded model; mask B: Valmy Spireor). The order of testing was random. Ease of use of the smartphone technology and the comfort of the frame were determined by questionnaire.Results Fit test passes increased from 5% without the frame to 70% and 95%, respectively, for masks A and B with the frame (p <0.01). Very few participants reported using the technology as difficult (n = 1/20) or the frame uncomfortable (n = 3/20) or difficult to wear (n = 0/20).Conclusion Customised frames produced using smartphone technology improved qualitative fit test pass rates for two commonly available FFP3 respirators. Using smartphone technology for frame design, wearing a frame and frame comfort levels were all acceptable to the majority of participants.

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.

Prediction of N95 Respirator Fit from Fogging of Eyeglasses: A Pilot Study

Aim and objective

Fogging of eyeglasses while wearing N95 respirators is common. It is commonly held that the N95 respirator has a poor fit if there is fogging of eyeglasses. We conducted this prospective, pilot study to determine if fogging of eyeglasses predicts poor fit of N95 respirator.

Materials and methods

Seventy volunteer healthcare workers from a tertiary intensive care unit in Sydney, Australia participated. The participants donned one of the following N95 respirators: three-panel flat-fold respirator (3M 1870), cup-shaped respirator (3M 1860), or a duckbill respirator. After a satisfactory "user seal check" as recommended by the manufacturer, the participants donned eyeglasses and checked for fogging. A quantitative fit test (QnFT) of the respirator was then performed (using PortaCount Respirator Fit Tester 8048, TSI Inc., Minnesota, USA). A fit factor of <100 on quantitative fit testing indicates poor fit. The sensitivity and specificity for fogging of eyeglasses (index test) to predict the poor fit of N95 respirator was determined, compared to QnFT (gold standard test).

Results

Fogging of eyeglasses as a predictor of poor respirator fit (i.e., fit factor <100 on QnFT) had sensitivity of 71% (95% CI, 54-85%) and specificity 46% (95% CI, 29-63%). The odds ratio of fogging as a predictor for poor fit was 2.10 (95% CI, 0.78-5.67), with a two-tailed p-value of 0.22 (not significant). The receiver operating characteristic curve for fogging of eyeglasses as a diagnostic test had the area under the curve of 0.59.

Conclusion

Fogging of eyeglasses is neither a sensitive nor a specific predictor for poor fit of N95 respirators.

How to cite this article

Kyaw S, Johns M, Lim R, Stewart WC, Rojas N, Thambiraj SR, et al. Prediction of N95 Respirator Fit from Fogging of Eyeglasses: A Pilot Study. Indian J Crit Care Med 2021;25(9):976-980.