Effectiveness And Use of Non-Medical Masks For The Public In Community Settings

Last Updated: September 17, 2020

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This Briefing Note was completed by the Research, Analysis, and Evaluation Branch (Ministry of Health) based on information provided by a member of the COVID-19 Evidence Synthesis Network. Please refer to the Methods section for further information.

Purpose

This note provides a summary of evidence on the effectiveness of non-medical masks including cloth/homemade and surgical masks and their use in community settings for all age groups. It also includes information from Canadian and non-Canadian jurisdictional statements about mask use in community settings.

*The full version of the Briefing Note including the Appendix can be accessed in the PDF file at the top of the page*

Key Findings

Analysis for Ontario

The decision about whether/how to enforce masking has been left up to individual municipalities.

Supporting Evidence

This section below summarizes the evidence on the types of masks and their effectiveness and summarizes the conditions in which it is recommended that masks are used in community settings. Additional details are provided in the Appendix.

Types of Masks and their Effectiveness

Scientific Evidence
  • Types of masks:
    • Cloth/home-made: Currently, there is no uniformity in the recommended design, material, layering, or shape of non-medical masks. The WHO recommends a minimum of three layers, with the following combination: 1) an innermost layer of a hydrophilic material (e.g., cotton or cotton blends); 2), an outermost layer made of hydrophobic material (e.g., polypropylene, polyester, or their blends), which may limit external contamination from penetration through to the wearer’s nose and mouth; and, 3) a middle hydrophobic layer of synthetic non-woven material, such as polypropylene or a cotton layer, which may enhance filtration or retain droplets.
    • Medical masks worn in non-medical settings: This mask category includes surgical masks but excludes N95 masks.
    • Other: Other face coverings may include plastic face shields, scarves or may be of a type not specified.
  • Effectiveness of masks: In general, the evidence supporting the effectiveness of wearing of medical and cloth facemasks in community settings is mixed, though overall most reports conclude that both types appear to have a small protective effect. The lack of conclusive findings stems largely from differences in study designs–experimental and modelling studies tend to under emphasize the protective role of facemasks, while observational studies tend to over emphasize them.
    • Medical/surgical masks versus cloth masks: Systematic reviews and rapid reviews found that medical masks were more effective in filtering out smaller particles than cloth masks. However, when applied to community settings with other public-health measures in place, the difference was not significant.
    • Effectiveness for adults versus children: No evidence was found related to differences in effectiveness of masks between adults and children. One guidance document indicated that the use of masks for children in the community should not impede development or learning outcomes and any requirements for masks should consider the feasibility of implementation within the specific context of each community.

Use of Masks in Community Settings

Scientific Evidence
  • Conditions of mask use:
    • Single-use masks should not be re-used; damp masks should never be worn and should be immediately changed.
    • Masks are more effective when used in conjunction with other public health measures including physical distancing and hand washing.
  • Adherence to mask wearing: Two systematic reviews found significant variation to adherence of mask wearing. In one review, adherence was significantly higher when required rather than suggested. Reasons for challenges with adherence included: experiences of discomfort, problems with communication, lack of breathability, and potential stigma related to indicating illness. Suggested solutions to help mitigate these challenges included education on the type and fabric of masks to be used and clarity on when and how they should be worn.
    • A July 2020 survey of Canadians (approximately 2,000 respondents) revealed the following:
      • About 60% of people reported wearing facemasks most of the time when they leave the house.
      • People who were most likely to wear masks “most of the time” were women, older adults, and those living in suburban areas.
      • About 30% of people reported being unaware that there is a mask wearing policy, and two-thirds of these people report not wearing masks.
      • About 30% of those who know there is a policy do not wear masks most of the time
  • Potential harms due to mask wearing: Harms related to mask wearing included some reports of headaches and feelings of a false sense of security when wearing a mask, which could potentially lead to a reduction in adherence to other public health measures. However, there is currently very little evidence related to harms and their potential effects on mask wearing.
    • The available evidence does not support concerns that wearing face coverings will adversely affect hand hygiene. In two studies, self-reported rates of hand washing were higher in the groups allocated to wearing masks.
International Scan
  • Mask use in non-healthcare settings: In Australia, Denmark, France, Germany, New Zealand, the United Kingdom (UK), and the United States (US) (with a focus on Maine, Oregon, and Vermont) the following information was identified:
    • Mask use in indoor spaces: Most jurisdictions require individuals to wear masks in indoor spaces (including while in transit) and outdoors when physical distancing cannot be maintained. The two exceptions to this at national level is Denmark and New Zealand, where there are currently no national requirements to wear masks, except on public transit in both countries.
      • Fines: Three countries (Australia, Germany and the UK) have implemented fines for not adhering to masking requirements.
    • Regional or state-level policies: Three countries, Australia, Germany, and US are taking state or regional approaches to masking requirements. However, Germany has also reached an agreement with 16 states to require masks (or something that covers the mouth and nose) in shops and on public transportation, with a fine of $80.85 CADf imposed for non-compliance. One German state (Saxony-Anholt) is the exception to this rule as it did not agree to introduce it given its low number of cases.
    • Exemptions: Exemption for mask requirements include children (with ages varying between five and 11) and those with physical or developmental limitations that make wearing a mask difficult.
Canadian Scan
  • Most Canadian provinces are suggesting that individuals wear non-medical masks when indoors and when physical distancing is not possible.
    • Required use of non-medical masks: Quebec, Nova Scotia, Newfoundland and Labrador, have put in place province-wide requirements.
    • Role of municipalities: The provinces of British Columbia (BC), Alberta, Saskatchewan, Manitoba, Ontario, and Prince Edward Island (PEI) have left the decision up to individual municipalities about whether and how to enforce masking.
    • Provinces that require masks in schools: BC, Alberta, Ontario, PEI, and the Northwest Territories require masking for children, teachers and staff at schools, though the grades in which requirements begins varying from junior kindergarten to grade seven.
      • Nunavut is the only province or territory where there is no requirement for children to wear a mask in school; children may be asked to put one on should rates of infection change.
    • Transit and other forms of transportation: In BC, all provincially run transit services require face masks to be worn. While none of the three territories are requiring face masks in public spaces, the Yukon and Nunavut are requiring that all travellers wear masks in airport buildings.
Ontario Scan
  • In Ontario,
    • The decision to require or enforce mask wearing has been left up to the municipalities.
    • Masks are required for children, teachers and staff at schools from grade four to 12. Students in Kindergarten to Grade 3 are encouraged to wear a mask.
    • The City of Toronto requires all individuals to wear a mask or a face covering in indoor public spaces, except for those below the age of two or those with specific medical conditions.
    • Businesses are required to develop a mask policy for their establishment and to communicate this with their team and customers. Owners of apartment and condominium buildings are also required to develop policies for their properties and to communicate this with tenants.
    • Simcoe County, Durham, Wellington-Dufferin-Guelph, York, Brampton and other municipalities have also mandated masks and face coverings for residents.
  • A Synthesis by Public Health Ontario offers the following key points about mask wearing:
    • Public mask-wearing is likely beneficial as source control when worn by persons shedding infectious SARS-CoV-2 virus.
    • Mandatory public mask policies have been associated with a decrease in new COVID-19 cases compared to regions without such policies.
    • Studies evaluating masking in children are limited and have demonstrated variable results with respect to their effectiveness for source control. However, studies have consistently shown lower adherence, especially in younger children.
    • Masking to protect the wearer is unlikely to be effective in non-healthcare settings. Existing evidence demonstrates that wearing a mask within households after an illness begins is not effective at preventing secondary respiratory infections.
    • There is variability in the effectiveness of homemade and cloth masks. Some materials adequately filter the expulsion of viral droplets from the wearer making them theoretically suitable for source control.
    • There are theoretical risks of harms from public mask use including self-contamination from improper use and facial dermatitis or discomfort. Children may experience more discomfort from wearing a mask compared to adults.

Methods

The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers as the pandemic continues. The following members of the Network provided evidence synthesis products that were used to develop this Evidence Synthesis Briefing Note:

  • Ontario Health (Quality). Effectiveness of Universal Mask Use: An Expedited Summary of the Evidence and Jurisdictional Scan, June 25, 2020.
  • Public Health Ontario. Wearing Masks in Public and COVID-19 – What We Know So Far. September 14, 2020.
  • Waddell K, Wilson MG, Gauvin FP, Moat KA, Wang Q, Ahmad A, Bhuiya A. COVID-19 rapid evidence profile #18: Which types of non-medical masks are effective in community settings for reducing the spread of COVID-19 for different populations and under different conditions? Hamilton: McMaster Health Forum, 4 September 2020.