Wearing a face mask has been recommended since the onset of the COVID-19 pandemic to help reduce the transmission of the coronavirus. Some people have even been wearing two face masks instead of one since the pandemic began. It’s becoming more popular since new, more contagious COVID-19 variants are circulating. But is wearing two masks really safer than one? Find out what the research says about one versus two face masks in protecting against COVID-19 virus infection.
In January 2021, the Centers for Disease Control and Prevention conducted an experiment with disposable medical procedure masks, which tend to fit more loosely than respirator masks like N95 face masks. In the experiment, a medical procedure mask was tightened by knotting the ear loops where they attach to the mask’s edges and then tucking in and flattening the extra material close to the face. As a result, the receiver’s exposure to simulated virus particles emitted from the source dropped by 95% when both the source and the receiver wore a modified medical face mask.
When wearing a cloth mask over a medical procedure mask, the wearer’s exposure to the coronavirus (simulated by potassium chloride particles) decreases by 90%. This is because the cloth mask helps the medical procedure mask fit more tightly to the wearer’s face and reduces edge gaps, which prevents leakage of air around the masks’ edges. Look for a cloth mask with multiple layers of fabric; a medical procedure mask with at least two layers also is best. When wearing both masks, be sure you can see and breathe without difficulty.
Other options to wear over a medical procedure mask to improve fit include solid or elastic mask fitters that are secured with head ties or ear loops. The CDC experiment also found that placing a sleeve of sheer nylon hosiery around the neck and pulling it up over either a cloth or medical procedure mask could improve the mask’s fit and reduce exposure to respiratory droplets and aerosols. Wearing a mask with a nose wire along the top also can improve fit by bending the wire over the nose so the mask fits close to your face.
During the CDC experiment, only two types of masks were used: a three-ply medical procedure mask and a three-ply cloth mask. Therefore, the CDC cautions that the same effectiveness may not be achieved when wearing different masks together, such as two cloth masks or two medical procedure masks. The CDC also cautions that, when tightening masks, to take care not to alter the shape of the mask so it no longer fully covers both the nose and the mouth.
Because disposable masks are not designed to fit tightly, there is no benefit to wearing two together because you still will have air gaps around the masks’ edges. The goal of the second—outer—mask is to push the edges of the inner mask against your face, and disposable masks will not do this due to their loose fit. In addition, N95 and KN95* respirator masks are not designed to be worn with any other mask. They already are designed to have a snug fit with filtration, so additional masks are not needed.
*N95 respirators are fabricated to U.S. design standards whereas KN95 respirators are fabricated to Chinese standards. Both are rated to filter out 95% of very small particles. Buy KN95s that meet the National Institute of Occupational Safety and Health (NIOSH) requirements from trusted medical supply companies. About 60% of KN95s in the U.S. may be fake and do not meet NIOSH requirements.
Proper masking plays a crucial role in helping reduce the spread of the coronavirus, but following COVID-19 protective measures also remains important. This includes social distancing of at least 6 feet apart from others outside your household, avoiding crowds and poorly ventilated indoor spaces, and washing hands often with soap for at least 20 seconds each time. Use hand sanitizer frequently when washing hands is not available.