Does Wearing 2 Masks Protect Against COVID-19 Better Than One?

The case for wearing a face mask to protect against SARS-CoV-2 is strong. According to a scientific brief from the Centers for Disease Control and Prevention (CDC), face coverings can reduce the risk of COVID-19 by more than 70%. But if wearing one face mask offers solid protection, does wearing two masks at the same time work even better? Some people started "double-masking" to increase their odds of staying COVID-free. What does the science say about this trend?

Wearing Two Masks: What Research Said

As of July 2022, there's some data to say that wearing two masks is better than one, but that depends on the kinds of masks you wear, and in what order you double up different masks. One August 2021 study published in JAMA Internal Medicine tested the filtration efficiency (FFE)—the percentage of particles the filter could protect you from—of single masks and different mask combinations.

Here's what researchers in the 2021 study found (The higher the FFE, the more protection you get from the mask.):

• Wearing a surgical mask under a cloth mask increased FFE most significantly (from 66% with just a surgical mask to 81% with a combo).
• Wearing a surgical mask on top of a cloth mask was less efficient than a surgical mask on its own.
• Wearing two surgical masks increased FFE (from 55% with one surgical mask to 66% with two).
• Doubling up on a cloth mask also increased FFE, but could make it harder to breathe.
• Single cloth masks performed worse than single surgical masks.

"Wearing two masks might be a reasonable idea if the filtration capability of the masks isn't very strong," Scott Segal, MD, Thomas H. Irving professor and chair of anesthesiology at Wake Forest Baptist Health in Winston-Salem, North Carolina, told Health.

Studies have found that multiple layers of cloth filter viral particles better than one single layer, and two layers of high-quality cloth with a tight weave perform best. "With poorer quality materials, more layers may perform better," Dr. Segal said.

Infectious disease expert Amesh Adalja, MD, senior scholar at the Johns Hopkins University Center for Health Security in Maryland, agreed that the effectiveness of wearing two face masks depends on the mask material. "Where you need to wear two masks depends on the quality of the mask," Dr. Adalja told Health. "It depends on the fit of the mask and how well it serves as a barrier."

What About Wearing a Separate Filter Inside the Mask?

Another mask trend had some people inserting a filtering material inside their mask, such as a piece of an air conditioning filter or coffee filter. As with double-masking, doing this might give you more protection if your mask doesn't fit well or the material quality is poor. If the mask is otherwise poorly functioning, this may improve its capability significantly, according to Dr. Segal.

"There is evidence that just as a coffee filter is an effective strain in limiting small coffee grains from seeping through, it might also filter some COVID-19 droplets," Leonard Krilov, MD, chief of Pediatric Infectious Disease at NYU Langone Hospital–Long Island, told Health. But Dr. Krilov added that a coffee filter inside a mask could be uncomfortable and make it harder to breathe—which would cause the wearer to tug at the mask and not keep it on appropriately. "Best to leave the coffee filter for its intended purpose of making a good cup of joe," Dr. Krilov said.

Bottom Line on Double-Masking

The issue comes down to quality vs. quantity: If a well-fitting, effective face mask isn't available, then two lesser-quality face masks worn together might improve protection.

However, if wearing two masks makes it difficult to breathe, ditch one of them. "No mask works if you can't comfortably wear it, and doubling up masks to the point that you can't breathe easily through them may make you either take them off or breathe around them, disabling the filtration effect," Dr. Segal said.

"It's a double-edged sword," Dr. Krilov agreed. "An extra barrier may sound like a good idea, but that extra layer may make it more difficult to breathe, making it more likely that you pull on the mask to breathe better and not keep it adequately in place."

Overall, as of July 2022, the CDC recommended to "wear the most protective mask you can that fits well and that you will wear consistently." Respirators such as N95 provide the highest level of protection. Here's how different types of masks stack up based on the protection they offer, from least to most protection, per the CDC:

• Loosely woven cloth masks (lowest level of protection)
• Layered finely woven masks
• Well-fitting disposable surgical masks and KN95s
• NIOSH-approved respirators such as N95s (highest level of protection)

The CDC said the mask must completely cover your nose and mouth and fit snugly against the sides of your face (no gaps). Don't wear a mask that's made of vinyl or another fabric that makes it difficult to breathe. The CDC also advised against a mask with exhalation valves or vents, as these let virus particles escape.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.