Thread by @jonlevyBU

1. FAQ for #BetterMasks in schools and colleges - a long 🧵

My goal is to provide information to parents, teachers, and students who want to protect themselves, but also to give sufficient background to allow people to advocate for policy changes.

2. Why am I doing this? Other than the fact that it is incredibly important given #Omicron, I have already prepared 3 versions of this for different schools this week. It is clear that many people don’t have the background needed to support mask upgrades.

3. The info below draws on insights from a number of experts, who I will try to acknowledge where possible. Apologies for any omissions. Errors are my own. Special thanks to @PatriciaFabianS and Wendy Heiger-Bernays @busphEH for their contributions to one of the FAQs.

4. Ok, let’s begin!

Q: Why use masks to protect against #COVID19?

A: Simply put, #COVIDisAirborne. COVID-19 is spread via airborne viral particles and the virus is transmissible from presymptomatic, asymptomatic, and symptomatic people to uninfected people.

5. When people breathe and talk, the virus is expelled and small viral particles remain in the air for a long time until the air is diluted with “clean” air or the air is filtered. The most effective method for decreasing exposure is with 😷 + adequate ventilation and filtration.

6. Q: Why was I told that cloth masks were fine, and now all of a sudden they aren’t?

A: The #Omicron variant is even more infectious than previous variants, making it even more important to use upgraded masking and ventilation/filtration to reduce exposure.

7. Q: Why use KF94, KN95, or N95 masks?

A: These masks do much, much better at keeping you from inhaling the virus. A typical cloth mask removes up to maybe 50% of the airborne particles. A well-fitted KF94/KN95/N95 can be more like 90-95+%.

jamanetwork.com/journals/jamai…

8. That's actually 5-10 times better than a cloth mask - for every 100 particles in the air, 50 would be inhaled with 50% removal, but only 5 would be inhaled with 95% removal.

9. As with many other respiratory viruses, it is likely that the more virus you inhale the more likely you are to get infected.

onlinelibrary.wiley.com/doi/10.1111/j.…

10. And if everyone wears masks, the benefits are multiplicative, since the masks would filter out both what is being exhaled and what is being inhaled, resulting in smaller inhaled doses.

11. Q: What is the difference between KF94, KN95, and N95 masks?

A: All these masks can have similar filtration efficiency. The labels just have to do with what country they come from - KF94 is from Korea, tested and approved by the Korean FDA. KN95 is the equivalent from China.

12. N95 is from the US, approved by NIOSH. Since this is occupational safety and health, they won’t work for younger kids. But any of these three would be appropriate for use at schools for kids or teachers.

13. Q: How do you decide which mask to purchase, given the importance of filtration efficiency, comfort, and fit?

A: For filtration efficiency, if authentic and tested, all of these types of masks do well, but performance can vary.

14. NIOSH does testing of N95s, but you can find systematic testing databases that include KF94s and KN95s elsewhere, including via @masknerd and at armbrustusa.com/pages/mask-tes….

15. For comfort, you want to make sure the masks are breathable so you can wear them for multiple hours. KN95s and KF94s have ear loops, whereas N95s generally have straps that go behind your head which both provides a tighter fit and greater long-term comfort for many.

16. One little-known fact is that the best KF94/KN95/N95s are actually more breathable than cloth, and more comfortable. You can teach in them, wearing them comfortably for many hours.

(I hiked in my Gerson N95 for > 1 hour, no problem and no fogged glasses)

17. Fit is key - you can have the best filtering mask material in the world, but if there are gaps where air can come in and out, you are breathing air that is not filtered. If you can feel your breath coming out the sides or your glasses fog up, you do not have an adequate fit.

18. However, it is incorrect that without a formal “fit test” you cannot have a protective mask. There are some very easy informal “fit tests” you can do at home. One is to simply blow out and see where you feel air, but @CorsIAQ has a more rigorous one that works well.

19. Here is @CorsIAQ’s content, summarized. Place several small mirrors or reading glasses (or knives or spoons) in the fridge for 2 to 3 min. Avoid putting them in the freezer, as they will get too cold and you will get condensation on lenses when you remove them.

20. Take the first one out and place it directly in front of your mask. As you breathe, the high water vapor content of your warm breath will condense on the lens, a good thing as it shows air going through the mask.

21. Now take out a second and put it at the edge of the mask near your chin, nose crease, or cheeks. You want to see as little, and preferably no, condensation as possible. Lack of visible condensation does not mean zero leakage, but does give a good indication of relative fit.

22. It is best to do the front of the mask first & edges after, as glass lenses will become cooler as they sit in the fridge and yields a safety factor.

(Apologies @CorsIAQ that I couldn’t add your original tweet and images to this thread - not adept enough to do so)

23. Q: Can I wear the KF94, KN95 or N95 more than once?

A:  Yes, you can actually wear them multiple times without a problem. But do not wash them! Good practice is to have a few and rotate them - wear one and hang it up or put it in a paper bag for a few days, then reuse.

24. You can generally get 40 hrs out of a KF94 or KN95, as long as they don't get wet or disgusting. Also watch that the elastic doesn’t stretch out or the nose piece loosen, which will decrease the effectiveness because it will not fit as well.

jem-journal.com/article/S0736-…

25. The N95s typically fail at the straps before they fail at the mask, so watch for strap stretching or breakage.

But the ability to reuse them cuts down on costs significantly.

26. Q: So where can I purchase #BetterMasks?

A: One warning is that there are a lot of counterfeits on the market. Projectn95.org is a reputable non-profit that has great options for adults and older kids, a bit less for younger kids.

27. If you are looking for KF94s, great options for younger kids, @masknerd has some listed websites and resources. I don’t want to endorse a specific business over another, but there are many Korean vendors with a wide range of products.

28. Lots of people have asked me which masks to buy. It’s hard to be specific, since it is a matter of what fits your face best as well as mask performance (filtration and breathability). And there are many options available.

29. For my family, 8 yr old has been very happy with Bluna FaceFit KN94. Adults and 11 yr old like Gerson N95 3230, Indiana foldable A105 N95, or the Bluna FaceFit KN94. Others rave about 3M Aura N95. But there are many others that could work well.

29. Although the masks are relatively inexpensive (roughly $1 each, so $0.25-$0.50 per use), many come in packages of 10-50, so it can be a big investment to find out something doesn't fit well. Schools ordering a few types for people to try and share would be wise.

30. Ok, back to the big picture - #BetterMasks work well, are comfortable, are affordable, and are necessary right now. Do what you can to protect yourselves in schools, but advocate for broader policy change.

31. In my view, any school should have a sufficient supply of #BetterMasks available to ensure universal access. This will keep our educators and students safe, our schools open, our parents able to work, and our communities with less #COVID19.

32. If your school does not have masking, #Omicron will spread quickly throughout the school, and things will close down. But even schools with cloth masks aren’t meeting the moment. Time to up our game, since our kids and university students deserve in-person education.

Addendum 1: Upthread I said KF94s/KN95s/N95s were “from” South Korea/China/US, respectively. Would have been more accurate to say “approved by”. Twitter shorthand may have been misleading.

Addendum 2: I find it incredibly sad that, at this point in the pandemic, the US has no strategy for general population mask approvals, providing masks to the public, or even communicating basic information about what #BetterMasks are and why you need them.

Addendum 3: South Korea has a formal process to evaluate masks for the public. The US relies on Amazon reviews, YouTube videos, and tweet threads. There are other differences in pandemic response, but the difference in Korean vs. US impact from #COVID19 is notable.