After All These Months We Finally Get A Little Science!

 So do masks work, or not?  And if so, how much?

The answer is:  it depends:

[A] group of researchers at Duke University created a simple technique to analyze the effectiveness of various types of masks which have become a critical component in stopping the spread of the virus.

The quest began when a professor at Duke's School of Medicine was assisting a local group buy masks in bulk to distribute to community members in need. The professor wanted to make sure the group purchased masks that were actually effective. 

 

In the study published Friday, researchers with Duke's physics department demonstrated the use of a simple method that uses a laser beam and cell phone to evaluate the efficiency of masks by studying the transmission of respiratory droplets during regular speech.

Imagine, having some curiosity and trying to learn something rather than having preconceived notions about what should be right! 

Public health experts have spent months emphasizing that masks are one of the most effective tools to help fight the pandemic, and many US states have now introduced some kind of mask requirement. 

 

But when testing their effectiveness, researchers discovered that some masks are quite literally useless.

Ruh roh, Shaggy.   

Neck fleeces, also called gaiter masks and often used by runners, were the least effective. In fact, wearing a fleece mask resulted in a higher number of respiratory droplets because the material seemed to break down larger droplets into smaller particles that are more easily carried away with air.

 

Folded bandanas and knitted masks also performed poorly and did not offer much protection.

 

"We were extremely surprised to find that the number of particles measured with the fleece actually exceeded the number of particles measured without wearing any mask," Fischer said. "We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work."

So what worked well?

The most effective mask was the fitted N95. Three-layer surgical masks and cotton masks, which many people have been making at home, also performed well.

We would expect N95 masks to work "well", but what does "well" mean?  And are there many three-layer homemade cotton masks out there, or did "three-layer" apply only to surgical masks?  What fraction of corona-cooties are stopped by these masks?

 

Do we even know yet if corona-cooties require water vapor in order to be transported?

This is shoddy journalism, probably written by someone whose mind doesn't think in the realm of science.  Let's look at the actual report.

Here are the 14 masks they studied, and here are their descriptions.  Could you pick up a mask at random and identify which of those 14 categories it fit into?  I can't.

And again, do corona-cooties even require water vapor to spread?

 

And is there evidence that having the entire population, over 99% of which do not have corona, wear masks, is a good idea?  Or should mask wearing be confined to people who actually have corona-cooties?  Because it doesn't matter how much water vapor your mask stops if there are no corona-cooties in it anyway.

If nothing else, this study shows us the (relative) vapor spread stopping power of these different masks.  At least that's a start.