TEACHERS. If you're heading back to the classroom soon, are concerned, and would like additional protections, I have 2 quick things you can do:

Better masks

Portable air cleaner w/ HEPA filter

Details and tips for you in this thread

1/n

Let's start w/ masks b/c these are the most important layer of defense. A typical cloth mask may only capture 25% of particles, but also could be as high as 75%. That's the problem. So, it's time to pick a #BetterMask. Here's my 'cheat sheet'

2/n https://twitter.com/j_g_allen/status/1354553833775632384?s=20

The power of masks comes when everyone wears one. If everyone in the room is wearing a blue surgical mask, which captures ~70%, respiratory particles have to go through 2 masks - mine, and yours. The *combined* impact is 91%!

And that's before distance or ventilation

3/n

If a student has a 70% mask, and now a teacher wears a KF94, for example, the *combined* benefit is 98%!

Immediate exposure reduction of 98% just from masks, even before any distance or any ventilation/filtration

More details on #BetterMasks here
4/n https://www.washingtonpost.com/opinions/2021/01/26/n95-masks-safest-next-best-options/

If you're having trouble finding a #bettermask, you can always double-mask using masks that are widely available.

-->Place cloth mask on top of blue surgical mask

That will help with the two "Fs": filtration and fit

Surgical mask for filtration, cloth mask to improve fit

5/n

If you're confused about N95, KF94, KN95, double-mask, welcome to the club! I try to explain this and clear up the confusion in this short clip. Only 90-seconds.

6/n https://twitter.com/j_g_allen/status/1354608059771973648?s=20

Now, let's move to portable air cleaners with a HEPA filter.

These are a quick way to add 'clean air' into a classroom, even if you're not sure about how well your room's ventilation system is working

7/n

Only buy a portable air cleaner with a HEPA filter. You don't need or want UV, ions, or any other gimmicky (and expensive) option

Then look for the device's 'clean air delivery rate', or CADR.

Quick guide: look for a CADR of 300 for every 500 square feet of classroom

8/n

We recommend trying to get 4-6 total air changes per hour in your classroom through any combination of ventilation (eg, open windows) and filtration (eg, portable air cleaners)

You can get 4 ACH just from a portable air cleaner if you size it right

9/n

To help figure out what size air cleaner to buy, use this tool we built w/ @ShellyMBoulder

--> Enter the size of your classroom
--> Enter the device's clean air delivery rate

The tool then tells you how many air changes per hour you are getting

10/n https://schools.forhealth.org/covid-19-tools/ 

If your school won't let you bring in a portable air cleaner with a HEPA filter, send me a note. I'll support you and your efforts, and I'm certain my other colleagues in this space will, too. @ShellyMBoulder @CorsIAQ @Poppendieck @linseymarr @stephensbrent + many.

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