Now we need 3-layer masks? Study advocates even greater barrier to COVID-19

• Three-layer masks have been found to keep you most protected from COVID-19 viral particles.
• Recent research found that only about 30% of large respiratory droplets are blocked by single-layer surgical masks.
• The N95 and KN95 masks remain the most effective at keeping you safe.

Forget double-masking: three-layer masks are more effective at preventing the spread of Covid-19 viral particles, according to a new study.

Researchers from the University of California-San Diego found that three-layered masks are better at preventing large particles from breaking down into smaller droplets, which makes them a better option for protection than two-layered efforts.

How are three masks more effective against COVID-19?

The study, which appears in the journal Science Advances, advocates for masks that have three layers but also notes that single and double-layer masks do provide protection in blocking some liquid particles, which is better than wearing no mask at all.

Mask wearing has once again made its way back into Americans’ lives following the Centers for Disease Control and Prevention’s decision to rollback mask recommendations for fully vaccinated Americans, a decision that came just two months after they said fully vaccinated people do not have to wear masks in public indoor places.

Researchers looked at surgical masks with one, two and three layers to see how these masks prevent small particles from passing through the mask pores. Using a droplet generator, the study found that large respiratory droplets containing the virus get atomized when they meet the surface of a single-layer mask, and these can pass through that layer. Only about 30% of droplet volume is restricted by single-layer surgical masks, while double-layer masks restrict around 91% of the droplet volume, according to the study.

However, the best protection is in three-layer masks — researchers said these masks had nearly zero droplet ejection.

“While it is expected that large solid particles in the 500–600-micron range should be stopped by a single-layer mask with average pore size of 30 micron, we are showing that this is not the case for liquid droplets,” said Abhishek Saha, professor of mechanical and aerospace engineering at UC San Diego.

“If these larger respiratory droplets have enough velocity, which happens for coughs or sneezes, when they land on a single-layer of this material it gets dispersed and squeezed through the smaller pores in the mask.”

The debate over mask-wearing comes as the Delta variant continues to rage across the U.S. and as many businesses begin mandating vaccines for workers returning to the office. It’s becoming clear that the COVID-19 pandemic is not ending anytime soon, and masking up remains the most effective way to keeping yourself and others safe.

A recent study found that surgical and cloth face masks are not the most effective masks, but N95 and KN95 — the gold standard of masks — continue to be the best options for crowded indoor events.

More on COVID-19:

• How effective is the Johnson & Johnson vaccine against the Delta variant — and do you need a booster shot?
• The race to produce antiviral pills — for COVID-19 — includes Pfizer, Merck, and other drugmakers
• Does natural immunity provide a better defense than vaccines?