Is a two-layer cotton mask just as effective as a surgical/medical mask at preventing the wearer from spreading COVID-19 to others?

Last updated: February 20, 2022
Yes. All the studies in this list that examine the question agreed on this conclusion. We identified one of these studies as a literature review, which is a type of study that reviews and often evaluates the findings of many studies on a question. This gives us more confidence that the answer is correct.
This short answer was generated by aggregating the answers that each of the studies below gave to the question (as indicated by State of K members) and adjusting for source quality and other factors. If key studies are missing or the answers attributed to individual studies are incorrect, the above answer could be wrong. For medical questions, don't rely on the information here. Consult a medical professional.
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Chart summary of 4 studies examining this question

All answers are assigned by State of K users. The label Couldn't Identify means that State of K was not able to determine whether a study answers the question "yes" or "no". This could be due to several factors. One possibility is that a study found some evidence to indicate that the answer to the question is "yes" and some evidence to indicate that the answer is "no". This often happens when a study uses two or more proxies to study the same phenomenon (i.e. firearm sales figures and self-reported firearm ownership rates as proxies for the prevalence of firearms) and the proxies yield different results when looking for correlations with another phenomenon (i.e. firearm-related deaths). Alternatively, the label may be applied if the phenomenon under study (i.e. whether breast milk improves cognitive function) is true for one group, but not another (i.e. true for girls, but not for boys). Yet another possibility is that a study found there was insufficient evidence to reach a conclusion regarding the question. Finally, the full text or abstract of a study may not have been written clearly or was inaccessible. This would make it difficult to determine how a study answered a question.

All labels of Literature Reviews and source quality are assigned by State of K. All labels of High Quality Source are assigned based on whether the publication in which the article appeared was ranked as Q1 by Scimago Institutions Rankings. Certain well-regarded think tanks are also given this label.

Literature Reviews
Although we recommend you consider all of the studies below, we believe the following study is a literature review, which surveys and evaluates many studies on this question:

SUMMARIES OF STUDIES
Total studies in list: 4
Sorted by publication year
1
Cloth face masks to prevent Covid-19 and other respiratory infections
"Objectiveto analyze scientific evidence on the efficacy of cloth masks in preventing COVID-19 and other respiratory infections.Methodintegrative literature review based on the following guiding question: What is the efficacy of cloth face masks in absorbing particles that cause respiratory infection? The search was conducted in eight electronic databases, without any restriction in terms of language or period.Resultslow coverage cloth face masks made of 100% cotton, scarf, pillowcase, antimicrobial pillowcase, silk, linen, tea towel, or vacuum bag, present marginal/reasonable protection against particles while high coverage cloth masks provide high protection.Conclusioncloth face masks are a preventive measure with moderate efficacy in preventing the dissemination of respiratory infections caused by particles with the same size or smaller than those of SARS-CoV-2. The type of fabric used, number of layers and frequency of washings influence the efficacy of the barrier against droplets."
AUTHORS
Thamires Sales Macêdo
Francisco Marcelo Leandro Cavalcante
Magda Milleyde de Sousa Lima
PUBLISHED
2020 Rev Lat Am Enfermagem
Literature Review
Yes
Yes
2
Performance of Fabrics for Home-Made Masks Against the Spread of Respiratory Infections Through Droplets: A Quantitative Mechanistic Study
"Respiratory infections may spread through droplets, Respiratory infections may spread through droplets and aerosols released by infected individuals coughing, sneezing, or speaking. In the case of Coronavirus Disease 2019 (COVID-19), spread can occur from symptomatic, pre-symptomatic, and asymptomatic persons. Given the limited supply of professional face masks and respirators, the U.S. Centers for Disease Control and Prevention (CDC) has recommended home-made cloth face coverings for use by the general public in areas of significant community-based transmission. There is, however, little information on the effectiveness of cloth face coverings in reducing droplet dissemination. Here, we ascertained the performance of 11 household fabrics at blocking high-velocity droplets, using a commercial medical mask as a benchmark. We also assessed their breathability (air permeability), texture, fiber composition, and water absorption properties. We found that droplet blocking efficiency anti-correlates with breathability; less breathable fabrics being more effective in blocking. However, materials with high breathability are desirable for comfort and to reduce airflow through gaps between the mask and face. Our measurements indicate that 2 or 3 layers of highly permeable fabric, such as T-shirt cloth, may block droplets with an efficacy similar to that of medical masks, while still maintaining comparable breathability. Overall, our study suggests that cloth face coverings, especially with multiple layers, may help reduce droplet transmission of respiratory infections. Furthermore, face coverings made from biodegradable fabrics such as cotton allow washing and reusing, and can help reduce the adverse environmental effects of widespread use of commercial disposable and non-biodegradable facemasks."
AUTHORS
M. Taher A. Saif
Leonardo P. Chamorro
Liu Hong
Shyuan Cheng
Bashar Emon
Onur Aydin
PUBLISHED
2020 MedRxiv
Yes
Yes
3
Textile Masks and Surface Covers – A ‘Universal Droplet Reduction Model’ Against Respiratory Pandemics
"The main form of COVID-19 transmission is via oral-respiratory droplet contamination (droplet; very small drop of liquid) produced when individuals talk, sneeze or cough. In hospitals, health-care workers wear facemasks as a minimum medical droplet precaution to protect themselves. Due to the shortage of masks during the pandemic, priority is given to hospitals for their distribution. As a result, the availability/use of medical masks is discouraged for the public. However, given that asymptomatic individuals, not wearing masks within the public, can be highly contagious for COVID-19, prevention of environmental droplet contamination (EnDC) from coughing/sneezing/speech is fundamental to reducing transmission. As an immediate solution to promote public droplet safety, we assessed household textiles to quantify their potential as effective environmental droplet barriers (EDBs). The synchronized implementation of a universal community droplet reduction solution is discussed as a model against COVID-19. Using a bacterial-suspension spray simulation model of droplet ejection (mimicking a sneeze), we quantified the extent by which widely available clothing fabrics reduce the dispersion of droplets onto surfaces within 1.8m, the minimum distance recommended for COVID-19 social distancing. All textiles reduced the number of droplets reaching surfaces, restricting their dispersion to <30cm, when used as single layers. When used as double-layers, textiles were as effective as medical mask/surgical-cloth materials, reducing droplet dispersion to <10cm, and the area of circumferential contamination to ~0.3%. The synchronized implementation of EDBs as a community droplet reduction solution (i.e., face covers/scarfs/masks & surface covers) could reduce EnDC and the risk of transmitting or acquiring infectious respiratory pathogens, including COVID-19."
AUTHORS
Sanja Ilic
Theresa T. Pizarro
Abigail R. Basson
Fabio Cominelli
Alex Rodriguez-Palacios
PUBLISHED
2020 MedRxiv
Yes
Yes
4
Medical mask versus cotton mask for preventing respiratory droplet transmission in micro environments
"The objective of this study was to investigate whether cotton mask worn by respiratory infection person could suppress respiratory droplet levels compared to medical mask. We recruited adult volunteers with confirmed influenza and suspected cases of coronavirus disease 2019 (COVID-19) to wear medical masks and self-designed triple-layer cotton masks in a regular bedroom and a car with air conditioning. Four 1-hour repeated measurements (two measurements for bedroom the others for car) of particles with a size range of 20–1000 nm measured by number concentrations (NC0.02–1), temperature and relatively humidity, and cough/sneeze counts per hour were conducted for each volunteer. The paired t-tests were used for within-group comparisons in a bedroom and in a car. The results showed that there was no significant difference in NC0.02–1 or cough/sneeze counts between volunteers with medical masks and cotton masks in a bedroom or a car. We concluded that the cotton mask could be a potential substitute for medical mask for respiratory infection person in microenvironment with air conditioning. Healthy people may daily use cotton mask in the community since cotton mask is washable and reusable."
AUTHORS
Kai-Jen Chuang
Shao-Ping Weng
Lian-Yu Lin
Kin-Fai Ho
PUBLISHED
2020 Science of The Total Environment
High Quality Source
Yes
Yes