Does a Face Mask Work if You’re the Only Person Wearing One?

Pointing to proof that one-way masking with an N95 works, infectious disease expert Carlos del Rio, M.D., says that when he is taking care of a patient with tuberculosis, for example, he doesn’t make the patient wear a mask, but he wears one. “And I have never been infected by tuberculosis by doing that,” says del Rio, professor of medicine at Emory University School of Medicine.

There’s plenty of research to back up the effectiveness of masks, too, including a recent California-based study published by the Centers for Disease Control and Prevention, which found that people who wore an N95-type mask in indoor public settings were 83 percent less likely to test positive for COVID-19 compared to those with no mask. 

Focus on fit of face mask

Fit is key, however. Even a high-quality mask doesn’t do much good if unfiltered air seeps in because it’s too loose. You want to make sure the mask completely covers your nose and mouth and that there are no gaps along the edges.

To test your fit, breathe in. If the mask collapses slightly, “that tells you that there's a tight-enough seal around your face, and that essentially all the air that you're breathing in is going through the filter part of the mask and not coming in through the edges,” Fabian says.

When you exhale, you shouldn’t see any condensation on your glasses. (You can use a cold spoon that’s been in the fridge for a few minutes to do this test if you don’t wear glasses.) “Because similarly, the air should just be coming out through the filter and not through gaps around your nose,” Fabian says.

Don’t have an N95 mask? Check to see if your local pharmacy is distributing them for free under a federal program. (The CDC has a free-mask locator online; you can also call 800-232-0233.) A word of warning: Beware of counterfeit masks being sold online, UC Riverside’s Brown says. The CDC maintains a list of N95 masks approved by the National Institute for Occupational Safety and Health, as well as examples of counterfeit versions.

A surgical mask still offers some protection against the virus, albeit less, experts say. Knotting the loops and tucking in the sides (see here for an example) can improve its effectiveness, a CDC study shows. Cloth masks, while better than nothing, are not especially great at keeping out the highly transmissible omicron variant and its increasingly contagious sibling strains, BA.2 and BA.2.12.1., which now make up the majority of infections in the U.S.

Other variables at play

A few other factors influence how well one-way mask wearing works. A big one is time. The longer you’re around an infected person, the bigger your risk for contracting COVID-19, del Rio explains.

Ventilation is another variable. A well-ventilated space — this could be as simple as opening windows and doors — reduces the concentration of airborne contaminants, including viruses. And while vaccines and boosters are most effective at preventing hospitalization and death from COVID-19, they, too, lower your risk of infection, federal data shows.

As pandemic-era restrictions continue to ease, it’s important to think through your risks and feel comfortable in the decisions you make, while also respecting the decisions others make, Fabian says. “And know that you can do something for yourself, irrespective of what the rest of the world is doing — and that’s wearing a mask,” she adds.

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.​