Measuring Total Filtration Efficiency of Surgical and Community Face Masks: Impact of Mask Design Features

Surgical and community face masks are used worldwide to reduce the transmission of respiratory infections in indoor environments. Performance parameters for these loose-fitting devices are mainly focused on material filtering efficiency, while, differently from face respirators, there are no standard methods for measuring the fraction of air leaking at the face seal. This study quantifies the total filtration efficiency (TFE), a parameter based both on filter efficiency and air leakage, of 50 face mask models with the aim of understanding the role of several mask design features on TFE performance. An instrumented head form equipped with sensors for measuring volumetric airflow and differential pressure was used to simulate the air exhalation from the mouth of a person wearing a face mask. A response surface method (RSM) was used to model the TFE experimental data. Results showed that TFE values ranged over a wide interval (from 5% to 73%), with better values at higher flow rates. A significant positive correlation was found between TFE and filter breathability. The presence of a nosepiece (NP) showed to increase the TFE on average from 4% to 6%, according to the flow rate. Significant improvements were associated only to nosepieces incorporating a metallic wire. The RSM model evidenced that the increase in the number of the filter layers and the use of a meltblown layer result in higher TFE only when a nosepiece is in place. Differently, the benefit of the nosepiece is less marked for masks made of highly breathable filters. To improve overall mask performance, the design of loose-fitting face masks should carefully compromise between breathability and filtration efficiency of the filter materials. The addition of a metallic nosepiece helps improving the TFE by limiting the air leaking at the face seal. © 1963-2012 IEEE.

The role of filter breathability in reducing the fraction of exhaled air leaking from surgical and community face masks

Face masks are used worldwide to reduce COVID-19 transmission in indoor environments. Differently from face respirators, there are no standards methods for measuring the fraction of air leaking at the face seal of loose-fitting masks such as medical and community masks. This study applies a recently developed method to quantify air leakage at the face seal to 14 medical and community mask models with the aim to understand the role of mask design and filter properties in air leakage. An instrumented head-form equipped with sensors for measuring volumetric airflow and differential pressure was used to simulate the air exhalation from the mouth of a person wearing a face mask. Results showed that the fraction of leaking air at the face seal is not negligible and can range from 10% to 95% according to mask model. The higher the exhaled airflow rate and the lower the amount of leaking fraction. A strong correlation was found between leaking fraction and filter breathability, indicating that a better breathability can lower air leakage. Highly breathable filtering materials should be employed in the production of medical and community face masks to maximize user comfort and minimize the fraction of exhaled air leaking unfiltered at the face seal. © 2022 IEEE.

From face-To-face environments to distance learning universities: The transition period of first-year students

The sudden transition from face-To-face into distance learning activities in higher education during the Covid-19 pandemic has highlighted the need to improve student induction and transition into distance learning settings. This study explores the experiences of first-year students at a distance learning university. Semi-structured interviews were conducted with students, aged 18-19, who transitioned from a face-To-face environment (school, college or another university) to distance-learning higher education. Thematic analysis yielded themes related to students early perceptions on distance-learning, experiences with learning and assessment, and social interactions. Noteworthy findings include students early misconceptions of distance-learning, distancelearning as a shelter for students with mental health issues, views on hybrid learning and continuous assessment, and approaches to socialising. Insights from this study have implications for how universities with new and existing distance learning practices design their induction and support programmes to facilitate student transition and enhance the first-year student experience. © HEAd 2022. All Rights Reserved.

Measuring breathability and bacterial filtration efficiency of face masks in the pandemic context: A round robin study with proficiency testing among non-accredited laboratories

Six Italian non-accredited laboratories participated to an interlaboratory study aimed at measuring Differential Pressure (DP) and Bacterial Filtration Efficiency (BFE) of three face-mask models using methods in-line with EN 14683 standard. Methodological non-conformities were annotated. Repeatability and reproducibility on quintuplicate samples were calculated according to ISO 5725-2. Sample stability was also assessed. Laboratories were ranked according to the total standard deviation over all samples and proficiency was evaluated using z-score according to ISO 13528. Although some non-conformities were present, performances for the DP measurements were always acceptable. One laboratory had to revise the bacterial suspension preparation for the BFE test. Overall, non-accredited laboratories working during pandemic emergency performed satisfactorily. Sample-to-sample variability impacted measurement repeatability. BFE values above 98% showed good repeatability (≤1.0%) and reproducibility (≤6.1%), but high BFE uncertainty was associated to community masks. Our findings suggest that relevant face-mask conformity standards should consider uncertainty of BFE and DP measurements. © 2021 The Authors