The Science of Masks

The Science of Masks

The Secretary of Health announced this week a statewide public health order requiring us to wear masks in public. So, how much do we really know about how much a cloth face covering can protect us from COVID-19? So much more than before!

Prior to this pandemic, there wasn’t a whole lot of research going on into the benefit of wearing cloth face coverings to prevent COVID-19, which, of course, we didn’t even know about until six months ago. Some researchers compared countries that promoted face masks as part of their early response to COVID-19 to countries, like the US, that did not. The countries that promoted face masks ended up with fewer cases than the countries that did not. Research is continuing, and we’re still learning more, but here’s what the science is telling us now:

  • COVID-19 be spread by people who do not know they have it (yet).
  • Having COVID-19 and not having any symptoms feels the same as feeling “healthy” or “normal.” The difference is, with COVID-19, you are contagious.
  • The virus that causes COVID-19 is principally spread by droplets that you exhale when you are normally breathing, as well as when you talking, singing, coughing or sneezing. These droplets can float in the air and infect people who are near you.
  • These droplets are more likely to reach other people if you are in an indoor space with poor ventilation, and within six feet of other people.
  • A cloth face covering helps you keep your breath, and those droplets, to yourself. You are even more likely to keep all those droplets to yourself if you are also standing six feet away from other people. And it works even better if the people around you are also wearing cloth face coverings.
  • Researchersreviewed the scientific literature looking at the effectiveness of surgical masks and cloth face coverings. They found that the masks and cloth face coverings were effective at preventing the spread of COVID-19 — if we wear them! The biggest limitation to their effectiveness was inconsistent mask use.

This means that people who feel healthy need to wear a cloth face covering in public places — especially indoors — and stay at least six feet away from other people.

And, no, wearing a cloth face covering is not at all likely to restrict your oxygen or make you breathe too much carbon dioxide or affect your immune system. If you feel dizzy or lightheaded, or have trouble breathing, sit down and remove your mask. If it continues, call 911.

Practice compassion. “Everyone shall wear a mask. Those who are not doing so are not showing their independence — they are only showing their indifference for the lives of others.” Sydney Morning Herald, February 3, 1919. Even before the modern research, people understood that wearing a mask is an act of compassion for others.

More information

Answers to your questions or concerns about COVID-19 in Washington state may be found at our website. You can also contact our call center at
1–800–525–0127. Hours: 6 am-10 pm, seven days a week.

Department of Health call center: 1–800–525–0127, 6 a.m. to 10 p.m, seven days a week.


Washington State Department of Health

Jun 23