How could wearing a mask reduce COVID-19 transmission?

Theoretically, wearing a mask can help reduce transmission in two ways:

• Masks may reduce the amount of respiratory particles entering the environment through coughing, sneezing, speaking, and breathing by trapping them in the mask (‘source control’). Respiratory particles can contain the SARS-CoV-2 virus. Therefore, reducing the amount of particles emitted by people infected with SARS-CoV-2 may reduce exposure risks for healthy individuals. Since asymptomatic and pre-symptomatic individuals can still spread the SARS-CoV-2 virus, mask use by ‘healthy’ people (people without COVID-19 symptoms) may be important in reducing exposure risks to others.

• Masks may offer some level of protection against personal exposure by preventing some respiratory particles from reaching your nose or mouth. The level of protection is dependent on the type of mask (or respirator) used (see this section for more info on mask types).

While both mechanisms may help prevent virus transmission, the primary benefit from the universal community-level use of masks is the reduction in the amount of SARS-CoV-2 entering the environment (‘source control’). See the below infographic which illustrates how masks may help reduce pathogen transmission via airborne particles.

Source: Science

Want to learn more about mask use for interrupting the spread of COVID-19?

• What types of masks are there and what are they designed to do?

• What is a N95 respirator and who should use one?

• What is a surgical mask and who should use one?

• What is a fabric mask, who should use one, and how should they be made?

• What should be considered when making fabric masks?

• Hygienic use of fabric face masks

• What is an occupational mask and who should wear one?

• Why doesn’t the WHO recommend that everyone wears face masks in all settings?

• What do we know about the effectiveness of masks to prevent and COVID-19 transmission in community settings?

• What can modelling studies tell us about the effectiveness of wearing masks?

• How well do masks work under laboratory (experimental) conditions?

• Do homemade masks increase the risk of respiratory disease?

• How might an evolving understanding of virus transmission affect mask recommendations?

• Should hygiene promotion staff wear masks to protect themselves and others?

Editor's note

Author: Jackie Knee
Review: Peter Winch, Julie Watson
Last update: 06.18.2020