The evidence is strong: masks limit the spread of COVID-19.

We have put together this page as a resource to clearly show the benefits of mask wearing in the nationwide effort to limit the spread of COVID-19. Information on this page is directly sourced from, the US group for the #Masks4All movement.

Why do the experts agree that masks limit the spread of COVID-19?

Note: Your mask helps protect others, and other people’s masks help protect you but masks are not a replacement for other critically important things like staying home, frequently washing your hands with soap and water, and maintaining your distance from other people (6 feet / 2 meters).


“If everybody [wears homemade masks], we’re protecting each other.”
Dr. Anthony Fauci, U.S. director of the National Institute of Allergy and Infectious Diseases (and the United States’ leading expert on infectious diseases)



Research finds speaking produces droplets that could be a mode of SARS-CoV-2 transmission. Asymptomatic people should wear masks to prevent spreading the virus through saliva droplets. Keep those around you safe by wearing a mask!”
Francis S. Collins, Director of The U.S. National Institutes of Health (the primary agency of the United States government responsible for biomedical and public health research)


“The big mistake in the U.S. and Europe, in my opinion, is that people aren’t wearing masks. This virus is transmitted by droplets and close contact. Droplets play a very important role—you’ve got to wear a mask, because when you speak, there are always droplets coming out of your mouth. Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others.” –China’s CDC Director 


There are “34 scientific papers indicating basic masks can be effective in reducing virus transmission in public — and not a single paper that shows clear evidence that they cannot.” –The Washington Post 



“Research supported by Nobel prize-winning virologist Harold Varmus tells us that placing a layer of cloth in front of a person’s face stops 99% of the droplets. And modeling by Yale researchers estimates that “the benefits of each additional cloth mask worn by the public are conservatively in the $3,000-$6,000 range due to their impact in slowing the spread of the virus”” –The Guardian 



“In a paper published in Nature on Friday, a five-year study from the University of Hong Kong and the University of Maryland has found that a simple non-fitted mask blocked 100% of coronavirus droplets and aerosol.” –The Guardian


“The available evidence suggests that near-universal adoption of non-medical masks when out in public, in combination with complementary public health measures could successfully reduce effective-R to below 1.0, thereby stopping community spread. Economic analysis suggests that the impact of mask wearing could be thousands of US dollars saved per person per mask “, so “we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.” –Face Masks Against COVID-19: An Evidence Review



Want the full scientific explanation? You can read more about the science here.

There are still a few skeptics about the effectiveness of masks, why?

The WHO only recommends masks for those infected with COVID-19 or those taking care of people infected with COVID-19. (source)

But ~50% of people who have COVID-19 are asymptomatic. (source)

So it follows basic logic that if we don’t know who has it and anyone who has it needs to wear a mask, then we should all wear masks.

“I think that wearing a mask is equally effective or more effective than distancing.”
Professor David Heymann, World Health Organisation (WHO) adviser

The Prime Minister of Slovakia released this statement after making masks mandatory: The WHO says “that only those infected should wear a mask. Only the future will show which countries have chosen the right approach and which haven’t.”

“The study proves the importance of washing hands and wearing face masks in public places because the virus can linger in the air attached to fine droplet particles.”
Study published in the peer reviewed Practical Preventative Medicine

“Implementing barriers to transmission, such as isolation, and hygienic measures (wearing masks, gloves and gowns) can be effective in containing respiratory virus epidemics.” –Study from the Cochrane Database of Systematic Reviews


Want the full scientific explanation? You can read more about the science here.

Why homemade masks keep yourself and others safe

Jeremy Howard, Founder of Masks4all and research scientist from University of San Francisco explains how masks keep you and others around you safe. 

“A double layer of 100% cotton cloth is about 70% as effective as a surgical mask at capturing small particles (up to five times smaller than coronavirus).”
Office of the Principal Scientific Advisor to the Government of India (study #1 & study #2)



  1. Protect others by not spreading the virus if you have it.

  2. Protect yourself by reducing your chances of catching the virus when you go outside.

  3. Reduce face touching by wearing something that covers your face.

Source: Covid-19: Why We Should All Wear Masks – There Is New Scientific Rationale




“Any type of general mask use (including homemade masks) is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence.” –2008 Study Published In The U.S. National Library of Medicine




“Currently available research supports the possibility that [coronavirus] could be spread via bioaerosols generated directly by patient exhalation. I’m not going to wear a surgical mask, because clinicians need those. But I have a nice western-style bandana I might wear. Or I have a balaclava. I have some pretty nice options.”
Dr. Harvey Fineberg, Chair of the U.S. National Academy of Sciences’ Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats

Now that we know that homemade masks can help end the COVID-19 crisis, how do we implement them?

Now that the science is widely accepted as fact, we need your help getting mandatory mask laws in place and if you haven’t already, please make a homemade mask.

Because my mask protects you and your mask protects me.

We now know that masks slash transmission of COVID-19. Modelling suggests if 80% of people wear a mask, we’ll stop the spread of the disease.

When we don’t have symptoms, in the early stages of infection, is when we’re most infectious. Countries with mask laws have 100x lower COVID-19 rates than other countries.

Masks can be made at home – they shouldn’t be medical grade, because hospitals need them. A scarf or bandana is fine, or make a mask out of a handkerchief.

Comparison between mandatory mask wearing and no masks.