Thread by @DavidLKeating

1/ To get maximum protection from #covid19, you need great filtration AND fit.

If your mask doesn’t fit well, you'll breathe in unfiltered air from leaks around your mask.

That could make the difference between 60-70% effective filtration and 95%+

A 🧵 on getting a good fit.

2/ I'm assuming you are wearing one of the #bettermasks, such as an #N95, N99, N100, KF94, FFP2, FFP3, non-fake KN95, etc and that you're happy with it.

(If yours doesn't fit well or you don't have one of these high-performance masks yet, I get to that below.)

3/ All high-quality masks will come with instructions -- read them!

If you have a 3M N95, you can often find good video or printed instructions by searching for "wear it right 3m XXXX" where XXXX is the model number.

General basic instructions here:.
uwsp.edu/rmgt/Documents…

4/ Watch this short video below to learn how to do a user seal check.

5/ This short printed guide by NIOSH is also useful.
cdc.gov/niosh/docs/201…

6/ Official CDC guidance here (scroll down to "Respirators"):
cdc.gov/coronavirus/20…

7/ This video by @masknerd has a nice under 3-minute segment showing how to adjust the fit of your mask. (It should start at 16:28)

8/ Here's a nice tweet thread by @CorsIAQ showing "a quick & dirty test of leakage around your mask."

https://twitter.com/CorsIAQ/status/1422433693117779977

9/ Many masks come with adjustable straps. If your mask has an adjustable strap, use it to obtain a tight fit. Many people who are getting a poor fit fail to adjust their ear or head straps.

10/ If you want maximum protection, you should avoid earloop masks. I know of no N95s with just earloops.

11/ But If you have an earloop mask and the straps do not adjust, your best bet is to buy or make an ear savers attachment, which not only take the pressure off your ears, but it will likely improve your fit.

12/ Alternatively, you may be able to cut the earloops in the middle and then tie them to use as headbands.

13/ If you have a fold-style N95 mask or KN95 mask, you need to work the nose wire to get a proper seal. It comes out of the package with a v-shape in the nose wire.

14/ Since no one has a sharp v-shaped nose, you will need to reshape the nose wire to get a better fit. The video in this tweet is an excellent explanation of how to fix the nose wire in fold-style mask.

https://twitter.com/amandalhu/status/1472725100168302592

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15/ Many get their best fit with an elastomeric mask. These masks have a soft material that will adapt to your face. Many people find them more comfortable.
@PPEtoheros

You can read more about good elastomeric options at this link.
masks4all.co/faqs-on-better…

16/ I highly recommend you read this excellent "Respirators FAQ: General Public" by 3M. Click this link for the full text. H/T @AbraarKaran
multimedia.3m.com/mws/media/1791…

17/ If you want the best fit, you're going to have to have a clean shave where the mask touches your face. (See the chart.)

If you can't accept the idea of getting rid of your beard, make it as short as possible, 1/4" or less, and wear a cup-style hard shell mask.

18/ If you wear a beard for religious reasons, consider the Singh Thattha technique. Info on that (and beards in general) at this link:
masks4all.co/faqs-on-better…

19/ If you want to go all out, you can get a professional fit test. There are professional kits for it. Like this one:
shop.projectn95.org/gerson-fit-tes…

Here's a paper that describes a DIY fit test at home. There are tweet threads on DIY versions.
medrxiv.org/content/10.110…

20/ Now if you don't have an N95 mask yet, get one, but don't buy a box of 20 or 50 without trying one!

Consider masks that come in different sizes and consider different designs. You might get a better fit from a different size or even a different type of mask.

21/ A mask that fits a friend or even a sibling well might not fit your face well.

This may be especially true for N95 masks, which come in different shapes, with cone/cup, v-fold, duckbill being the most common. One of those shapes might work better on your face.

22/ By far the best option (and only so far) to find the best N95 is the @armbrust_usa Mask Sampler Kit (available later this month).
armbrustusa.com/collections/us…

I'm hoping @projectN95 will do the same kind of kit someday.

23/ Another great option for N95 class protection is the @FixTheMask brace plus @armbrust_usa surgical masks. The brace comes in different sizes. If nothing else, it can tide you over inexpensively until you find the right N95 for you.

armbrustusa.com/collections/ma…

24/ If you have a hard-to-fit face, consider trying the SoftSeal brand masks that have a silicone seal around the edges. It comes in multiple sizes, including small. You can order a 3-pack so you don't have to spend a lot to try it.
softsealmask.com

25/ If you need an N95 right away, like today, check out this thread:

https://twitter.com/DavidLKeating/status/1475871569062805517

26/ For more info on better masks, check out the Masks4All page:
masks4all.co/faqs-on-better…