Evidence map›Paper›PMID 33075669›Full record

ArticlePublic health2020

Home-made masks with filtration efficiency for nano-aerosols for community mitigation of COVID-19 pandemic.

I W-S Li, J K-M Fan, A C-K Lai, C-M Lo

Open access · greenAbstract read
In one paragraph

Article in Public health, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 9 papers, 2 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
9citing papers in PubMed, 2 pooled it
2.4field-weighted citation impact, top 9% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

9 citing papers in PubMed, 2 syntheses or guidelines pooled it, 21 citations in OpenAlex.

  1. A Review of Filtration Performance of Protective Masks.International journal of environmental research and public health · 2023
    Pooled it
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

4 authors at 3 institutions in 2 countries.

I W-S LiHKU-Pasteur Research Pole, School of Public Health, The University of Hong Kong, Sassoon Road, Pokfulam, Hong Kong, China. Electronic address: irisli.irisli.irisli@gmail.com.
J K-M FanDepartment of Surgery, The University of Hong Kong-Shenzhen Hospital, Futian District, Shenzhen, China; Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Sassoon Road, Pokfulam, Hong Kong, China.
A C-K LaiDepartment of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
C-M LoDepartment of Surgery, The University of Hong Kong-Shenzhen Hospital, Futian District, Shenzhen, China; Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Sassoon Road, Pokfulam, Hong Kong, China.
University of Hong Kong - Shenzhen Hospital · CNCity University of Hong Kong · HKHKU-Pasteur Research Pole · HK

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

objectivesThe novel coronavirus disease 2019 (COVID-19) epidemic that emerged in December 2019 has rapidly evolved in recent months to become a worldwide and ongoing pandemic. Shortage of medical masks remains an unresolved problem. This study aims to investigate the filtration efficiency (FE) of home-made masks that could be used as alternatives for community mitigation of COVID-19. STUDY

designExperimental observational analytic study.

methodsThe FE of home-made masks and medical masks (as the control) were tested under laminar flow within a scaled air duct system using nebulised NaCl aerosols sized 6-220 nm. The size-resolved NaCl aerosol count was measured using a scanning mobility particle-sizer spectrometer. Home-made masks with an external plastic face shield also underwent a splash test. In addition, the fibre structures of medical masks were studied under an electron microscope after treatment with either 75% alcohol or soap and water at 60 °C.

resultsThe FE of the home-made masks at 6-200 nm were non-inferior to that of medical masks (84.54% vs 86.94%, P = 0.102). Both types of masks achieved an FE of 90% at 6-89 nm. A significantly higher FE was achieved when one piece of tissue paper was added adjacent to the inner surface of the medical mask than medical mask alone (6-200 nm: 91.64% vs 86.94%, P < 0.0001; 6-89 nm: 94.27% vs 90.54%, P < 0.0001; 90-200 nm: 82.69% vs 73.81%, P < 0.0001). The plastic face shield prevented the home-made mask from fluid splash. The fibre structures of the external surface of medical masks were damaged after treatment with either 75% alcohol or soap and water at 60 °C.

conclusionsThe home-made masks in this study, which were made of one piece of tissue paper and two pieces of kitchen towels, layered from face to external, had an FE at 6-200 nm non-inferior to that of medical mask materials, which had a certified FE of ≥95% at 3 μm. In the current COVID-19 pandemic with the shortage of medical masks, these home-made masks combined with an external plastic shield could be used as an alternative to medical masks for community mitigation. In addition, one piece of tissue paper could be placed adjacent to the inner surface of a medical mask to prolong effective lifespan of the medical mask. These demand reduction strategies could be used to reserve medical masks for use in healthcare and certain high-risk community settings, such as symptomatic persons, caregivers and attendees to healthcare institutions.

Indexed as

AerosolsCoronavirus InfectionsCOVID-19FiltrationHumansMasksNanoparticlesPandemicsPneumonia, ViralAerosolsCOVID-19Filtration efficiencyHome-made masksNano-aerosolsPandemicSARS-CoV-2

Identifiers

PMID33075669
PMCPMC7466940
OpenAlexW3082067050

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.