CDC: Double masking can block more than 90% of infectious particles

Virus Outbreak Pence
Posted at 4:29 PM, Feb 11, 2021
and last updated 2021-02-11 17:49:35-05

TAMPA, Fla. — As the transmission of the COVID-19 virus reaches new records, you’re likely seeing more and more people heading out with two masks on. So the big question is, are these people paranoid, or are they proactive?

New research from the CDC shows it’s likely the latter.

“What they’re trying to tell us is that the tighter the mask is, the better it is,” said Dr. Charles Lockwood, Dean of USF’s Morsani College of Medicine.

It’s not rocket science, in fact, if you think about it, it’s pretty common sense.

“It’s just reducing leakage,” said Dr. Lockwood.

If air is coming out the sides of your mask, particles are probably spreading. So the CDC’s endorsement of double masking aims to prevent that leakage.

“What the CDC showed is that when you combine a surgical mask, which is what I would use in the operating room, with a cloth mask… you combine those two, you reduce the risk of infection by 95%,” said Dr. Lockwood.

The CDC study showed that wearing an unknotted surgical mask alone blocked 42% of the particles from a simulated cough. A cloth mask alone blocked 44.3%. And the combination of the two blocked 92.5% of cough particles.

The study also showed that when the source was unmasked, and the receiver was wearing a double mask, the receiver’s exposure was reduced by 83%, versus 64.5% when the receiver is only wearing a knotted surgical mask.

However, when both the source and the receiver were both fitted with double masks, exposure to the receiver was reduced by 96.4%. And when both the source and the receiver were fitted with a knotted surgical mask, exposure to the receiver was reduced by 95.9%.

So essentially, if you and the people around you knot the ear loops of your surgical mask, and combine it with a cloth mask, it blocks more than 95% of particles.

“It’s literally like wearing an N95 mask, and everybody has access,” said Dr. Lockwood.

But the benefit falls to around 80% if only one of you is double masking.

Dr. Lockwood also assures that double masking will not affect your oxygen levels.

“What’s gonna really affect your oxygen level is being in the intensive care unit ventilated because you have viral pneumonia and you can’t get any oxygen,” said Dr. Lockwood.

But it will slow the spread as we reach toward herd immunity through vaccination. Double masking will buy us time.

“I’m making a wild guess that we will be through it all by August 1st, so it’s not forever, it’s just for a few more months,” said Dr. Lockwood.

While the CDC is not officially changing their mask-wearing guidelines, they are updating information about masks for the public on