Why snug, multi-layered masks are more effective

The best protection we have against COVID-19 continues to be vaccines plus booster shots. Early data from South Africa and the United Kingdom indicates a booster shot provides 75% effectiveness against infection with the Omicron variant.

But we can’t relax our behavior when it comes to masking. COVID-19 spreads when an infected person breathes out droplets and tiny particles that contain the virus. Other people can then inhale these droplets and particles. Because the Omicron variant spreads more easily than the Delta variant, wearing a well-fitting mask is more important than ever to slow the spread of COVID-19.

Everyone should wear a mask indoors and in crowded outdoor settings to protect themselves and those around them. Wearing two masks, in fact, is even better. Start with a disposable surgical mask next to the face, followed by cloth mask on top that fits snugly so that less breath (and particles) escapes. Do not wear two disposable masks. You can also consider a single high-filtration efficiency mask designed for a tight fit to the face. These include N95, KN95 and KF94 respirators from trusted sources.

Combine masking with social distancing and frequent handwashing for a winning strategy to end this pandemic.

Additionally, the Centers for Disease Control and Prevention (CDC) estimates more than 50 percent of COVID-19 transmission occurs from people who either don’t have symptoms or have not yet developed symptoms. This underscores the importance of mask wearing for everyone.

Dr. Ali Hamade, senior health advisor at the Oregon Health Authority, said, “To maximize mask efficiency, you need effective filtering material and a tight fit to the face. The better the combination of these two qualities, the fewer particles you release or inhale. Fewer virus particles in the air can result in a lower risk of transmission from an infected person.”

Hamade also noted the importance of good ventilation indoors to refresh the air. An air purifier (HEPA, preferred) can also help reduce the number of any virus-containing particles in indoor air when ventilation is not adequate.

Summary of masking tips

  • Masks must be worn over the mouth and nose, which are both potential habitats for viruses.
  • A cloth mask may be worn over a disposable mask. This adds a layer and improves the poor fit of disposable masks. Do not layer two disposable masks.
  • A high-filtration efficiency mask with a tight fit to the face is another option. These include N95, KN95, and KF94 respirators. Be careful of counterfeit items among these products that might not have the desired filtration efficiency.
  • Do not wear masks with ventilation valves. These ventilation valves allow particles and droplets to escape into the air.
  • Choose a mask that fits snugly against your face and is secure under your chin. A mask that has gaps around your nose or along your cheeks allows air to freely leave or enter. Masks with nose wires can improve the fit and ensure most air and breath is being filtered through the mask.
  • A cloth mask with multiple layers of washable, breathable, tightly woven fabric blocks more droplets than a cloth mask with only one layer of fabric. A study by the University of Illinois found the first layer reduces the speed of the droplets that escape, thereby allowing the second layer to trap and block most of the remaining droplets, as much as 94 percent total. Some masks have space for an additional layer of fabric to be inserted.