Outward and inward protections of different mask designs for different respiratory activities

Mapping Intimacies ◽

10.1101/2021.04.07.21255097 ◽

2021 ◽

Author(s):

Xueqi Koh ◽

Anqi Sng ◽

Jing Yee Chee ◽

Anton Sadovoy ◽

Luo Ping ◽

...

Keyword(s):

Droplet Size ◽

Protection Efficiency ◽

Surgical Masks ◽

Additional Protection ◽

Filter Layer

We evaluate the outward and inward protections of different mask types (N95, surgical and two cloth mask designs) taking into account the imperfect fit on the wearer. To this end, we built a manikin to simulate exhaling, coughing and inhaling of aerosol droplets 0.3-5.0 um in diameters. The outward and inward protections depend on many factors, including the droplet size, the mask fit and the presence of a filter layer. Here, we show that cloth and surgical masks with a non-woven filter layer can achieve a combined outward and inward protections between 50% and 90%. Removing the filter layer greatly reduces the protection efficiency to below 20% for the smallest droplet size. While a well-fitted N95 masks offer protection efficiency close to 100%, a poorly fitted N95 mask with gaps offers less protection than a well-fitted surgical/cloth mask. We also found that double masking or the wearing of cloth mask on top of a surgical mask is only effective at reducing outward droplet emissions when coughing, while offering no additional protection when exhaling/inhaling as compared to a single cloth/surgical mask. The results of our work can inform the implementation of mask mandates to minimize airborne transmissions of coronavirus disease of 2019 (COVID-19).

Download Full-text

Surgical Masks for Protection of Health Care Personnel Against Covid-19: Results from an Observational Study

Clinical & Investigative Medicine ◽

10.25011/cim.v44i2.36355 ◽

2021 ◽

Vol 44 (2) ◽

pp. E48-54

Author(s):

Zhengqi Pan ◽

Huijing Zhang ◽

Jianming Yang ◽

Shengli Tang ◽

Zhenshun Cheng ◽

...

Keyword(s):

Health Care ◽

Observational Study ◽

Hand Washing ◽

Health Care Personnel ◽

Intimate Contact ◽

Preventative Measures ◽

Surgical Masks ◽

Additional Protection ◽

Student’S T ◽

Index Cases

Purpose: The aim of the study was to describe the use of masks among health care personnel (HCP) exposed to index cases of coronavirus disease 2019 (COVID-19), and to evaluate any association with infection rate. Methods: We did a retrospective, observational study of HCP at Zhongnan Hospital of Wuhan University for the management of COVID-19 (before person-to-person transmission was official confirmed, no additional protection was provided). A questionnaire was given to all staff listed on the roster in the clinical regions providing care for index patients with COVID-19. All participants were surveyed regarding hand-washing and use of surgical masks and gloves and were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Data were analysed (Student’s t test and Pearson χ2 test) for an association between infection and use of personal protective equipment. Results: Exposure of a total of 299 non-infected and 30 infected staff was confirmed. None of the 149 staff who reported use of all three preventative measures (hand-washing and use of gloves and masks) became infect-ed. In contrast, all 30 of the staff who became infected had omitted at least one of the measures. Fewer staff who wore surgical masks (P=0.000003) became infected compared with those who did not. Infections rates were significantly lower in HCP from the internal medicine departments, as these personnel generally wore masks. Conclusion: An association was found between SARS-CoV-2 infection of HCP and the non-use of masks when working with index cases in clinical settings. We recommend that all HCP follow the strict instructions for prevention and treatment of nosocomial infection during intimate contact with COVID-19, especially staff from surgical departments.

Download Full-text

Use of respirator vs. surgical masks in healthcare personnel and its impact on SARS-CoV-2 acquisition: a prospective multicentre cohort study

10.1101/2021.05.30.21258080 ◽

2021 ◽

Author(s):

Sabine Haller ◽

Sabine Guesewell ◽

Thomas Egger ◽

Giulia Scanferla ◽

Reto Thoma ◽

...

Keyword(s):

Risk Behaviour ◽

Healthcare Personnel ◽

Surgical Masks ◽

Mask Type ◽

Multicentre Cohort Study ◽

Additional Protection ◽

Antigen Tests ◽

The Impact ◽

Multicentre Cohort

Background There is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. We analysed the impact of filtering facepiece class 2 (FFP2) vs. surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW). Methods Our prospective multicentre cohort enrolled patient-facing HCWs from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferred mask type when caring for COVID-19 patients outside of aerosol-generating procedures (AGP). For those performing AGPs, we asked whether they used FFP2 irrespective of the patients COVID-19 status (i.e. universal use). The impact of FFP2 on i) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and ii) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed. Results We enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2 respirators. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users (median follow-up 242 days); seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was non-significantly associated with a decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0.8, 95% CI 0.6-1.0, p=0.052) and seroconversion (adjusted odds ratio [aOR] 0.7, 95% CI 0.5-1.0, p=0.053); household exposure was the strongest risk factor (aHR for positive swab 10.1, p<0.001; aOR for seroconversion 5.0, p<0.001). In subgroup analysis, FFP2 use was clearly protective among those with frequent (>20 patients) COVID-19 exposure (aHR 0.7, p<0.001; aOR 0.6, p=0.035). Universal FFP2 use during AGPs showed no protective effect (aHR 1.1, p=0.7; aOR 0.9, p=0.53). Conclusion Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients.

Download Full-text

Size- and Time-Dependent Particle Removal Efficiency of Face Masks and Improvised Respiratory Protection Equipment Used during the COVID-19 Pandemic

Sensors ◽

10.3390/s21051567 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1567

Author(s):

Anja Pogačnik Krajnc ◽

Luka Pirker ◽

Urška Gradišar Centa ◽

Anton Gradišek ◽

Igor B. Mekjavic ◽

...

Keyword(s):

Removal Efficiency ◽

Time Dependent ◽

Respiratory Protection ◽

Particle Removal ◽

Scanning Mobility Particle Sizer ◽

Protection Efficiency ◽

Surgical Masks ◽

Size Of Particles ◽

Particle Sizer ◽

Respiratory Droplets

Size- and time-dependent particle removal efficiency (PRE) of different protective respiratory masks were determined using a standard aerosol powder with the size of particles in the range of an uncoated SARS-CoV-2 virus and small respiratory droplets. Number concentration of particles was measured by a scanning mobility particle sizer. Respiratory protective half-masks, surgical masks, and cotton washable masks were tested. The results show high filtration efficiency of FFP2, FFP3, and certified surgical masks for all sizes of tested particles, while protection efficiency of washable masks depends on their constituent fabrics. Measurements showed decreasing PRE of all masks over time due to transmission of nanoparticles through the mask-face interface. On the other hand, the PRE of the fabric is governed by deposition of the aerosols, consequently increasing the PRE.

Download Full-text