Our latest research article exploring the relationship between humidity, the properties of respiratory particles, and the survival of viruses. In collab with @jfdavies and @linseymarr. I try to articulate implications here. 1/n

pnas.org/content/119/4/… TLDR: Public health implication is that viruses likely survive in aerosol particles across wide range of relative humidity (RH), so ventilation, filtration, etc. are important (of course!). The ideal RH is likely 55-60% (any higher and mold is issue) 2/n

As an aerosol scientist with expertise in the niche sub-field of droplet fragmentation, I’ve been meaning to provide some commentary on this article for a while. What does it tell us about masks? Here’s what this article tells us and doesn’t tell us. 1/n

advances.sciencemag.org/content/7/10/e… Key observation 1: droplet penetration/ fragmentation occurs at high velocity and large droplets (coughing/sneezing conditions).

Takeaway: you should not be out in public coughing and sneezing (this goes for with or without a mask) 2/

1/ Some prelim observations: When shooting 100 micron water droplets at a strip of Buff-brand neck gaiter (95% polyester, 5% spandex, woven - material is more important than style) at ~1 m/sec, I saw no droplet breakup and no transmission through the mask. 2/ In the image above, I was personally surprised to see that 100,000 droplets actually accumulated into a macroscopic drop that didn't drip through the mask; the wonders of surface tension.

Is wearing a "neck gaiter" a bad thing? I am going to try and clarify a few things in a thoughtful way.

https://twitter.com/washingtonpost/status/1293170815052152835

First and foremost, the style of mask does not matter as much as the material. I interpret "neck gaiter" to be the sports-style spandex, and authors state "The gaiter tested by the researchers was described in the study as a 'neck fleece' made out of a polyester spandex material"

Much discussion lately in aerosol/disease transmission communities about the “5 micron cutoff” where droplets supposedly fall to ground w/in 1-2 m. @jljcolorado and @linseymarr has suggested ~50 microns.

Here’s some video evidence for that. 50 micron droplets wafting in lab... Mind you, I’ve arranged my lab to minimize air currents, and they still easily float around (without a propeller: imagine that). It doesn’t take much convention to elevate picoliters of volume. Imagine a typical indoor environment with doors opening and people talking...