Share this page!

Dr. Alex Huffman Profile picture
Twitter logo
14 Jan, 15 tweets, 13 min read
CDC came out with another incremental update on #mask & #respirator guidance today: cdc.gov/coronavirus/20…

Clarifies N95s aren't in short supply & can be worn again!

It's still not perfect, but it feels like we're at least inching in the right direction. Some thoughts via a🧵.
2/ New statement that most respirators (i.e. #N95s) "are disposable and should be discarded WHEN they are dirty, damaged, or difficult to breathe through."

So you CAN #ReuseN95s‼️
See, e.g.:

That's *much* better guidance than to toss after a single use!
3/ Also clearly states that:
"Loosely woven cloth products provide the least protection ... and well-fitting NIOSH-approved respirators (including #N95s) offer the highest level of protection."

YES!!
4/ The statements that tight-fitting #N95s offer better protection than other types of masks is not exactly ground-breaking, but glad CDC is getting on board.
Tons of examples of this messaging. But no matter what, make sure the mask is tightly worn.
5/ The CDC retained the section clarifying that many #KN95 respirators from the open marketplace are counterfeit and may not provide sufficient protection.

See their links or @projectn95 for help to think through possibly suspect versions. Or just get a NIOSH-stamped #N95.
6/ One thing I don't yet love is CDC guidance about procedure (surgical) masks. They clarify that you should not wear these masks with gaps for a loose fit.

The problem is that these aren't designed for a tight fit. So without a mask brace (@FixTheMask) the fit is usually poor.
7/ Remember it isn't just about the TYPE of mask, but esp. about the FIT of that mask.

N95s (many KN95, KF94, & even surgical) have excellent filtration - but if they are loosely draped on your face the air just goes around them.
Upgrade, but make it fit!
8/ The CDC director has made some now famous statements that N95s are uncomfortable. That's because she's been pushing the wrong respirators. Follow @AbraarKaran for plenty of comments on #ComfortableN95s.
washingtonpost.com/outlook/2022/0…
9/ You may still hear push-back on N95s being $$ b/c they should be used only 1x. Aerosol scientists & other mask experts have been encouraging public to reuse #N95s for a while, so I'm glad that it has trickled into the mainstream: cnn.com/2022/01/13/hea…
10/ Today's update by #CDC is just the latest in an incremental walk toward better #mask guidance. I talked through some of the changes from another one of their important updates on Sept. 11, 2021. This one has more analysis & resources links in thread:
11/ There have been a lot of previous #CDC updates on mask guidance as well, including this one from Feb. 10, 2021, as summarized here by @DrEricDing:
12/ To stay up on CDC mask updates & #BetterMasks or #N95s, see also excellent old & new 🧵's by @AbraarKaran @masknerd @claire_horwell @PPEtoheros @sri_srikrishna @trishgreenhalgh @jeremyphoward @DrEricDing @CPita3 @projectn95

🔹
13/ For other new & archived updates or articles on #masks or other topics, search (Cntrl-F) on the various tabs on this #openaccess resource on the airborne transmission & prevention of COVID.
Not only articles, but search a selection of threads on tab 5.
bit.ly/3fzmB16
14/ Same idea about CDC update on masks/N95s, by @ErinSandersNP & @tmprowell, but gets to the point much more quickly & with much more enthusiasm than I could muster today. 😉

Still moving forward, but I agree that this is a very important step! 😷
15/ Or for the even shorter version, today's CDC graphic.

🔹 To be clear, better protection in a line ⬅️ moving from right to left
🔹 And a minor quibble here, but #N95 masks filter >95% of particles at 0.3 microns (and nearly *💯%* at all other sizes!)

• • •

Missing some Tweet in this thread? You can try to force a refresh
　

Keep Current with Dr. Alex Huffman

Dr. Alex Huffman Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @HuffmanLabDU

Dr. Alex Huffman Profile picture
12 Jan
Really happy to see our paper led by @DaveyRachel1 just out in the #Forefront section of @AnalBioanalChem: rdcu.be/cEJN7

Improves a procedure to expose surrogate proteins to urban air (especially NO2, O3) to quantify changes in protein nitration ➡️ allergies, etc.
1/🧵 Image
2/ @DaveyRachel1 did a great job of quantifying & improving each step of the #bioanalytical procedure; ozone loss across PM filters, extraction & detection efficiencies, even good old analytical #FiguresOfMerit sensitivity & limit of detection.
rdcu.be/cEJN7 Image
3/ Possibly the most broadly useful piece is the data showing ozone loss across several filter types. The HEPA capsule scrubbed >60% of the ozone (bad if you're trying to quantify ozone). Kynar removed only 3%.
Important if using filter to remove PM, while quantifying O3 behind. Image
Read 6 tweets
Dr. Alex Huffman Profile picture
6 Jan
If you have more experience & credibility than Dr. @brosseau_lisa on topics of industrial hygiene, aerosol science & mask use, etc. - then by all means speak up.
Otherwise, dispense w/ silliness that surgical masks are safer than N95s. Use #BetterMasks.
🔹cidrap.umn.edu/news-perspecti…
2/ See also this additional flurry of tweets by @brosseau_lisa on the importance & use of high-quality N95 respirators:
🔹
🔹
🔹
🔹
🔹
3/ Regarding new mask mandates:
“Once you go into a store & you know you’re gonna be there for more than a couple minutes, you’ve got to wear a respirator.”: @brosseau_lisa
Look for NIOSH stamp & a tight fit. "If it has ear loops, it's not a respirator."
minnesota.cbslocal.com/2022/01/06/bes…
Read 4 tweets
Dr. Alex Huffman Profile picture
5 Jan
It's frustrating to see pervasive misunderstanding that N95 masks (respirators) need to be fitted or they are useless. Some of the same people champion surgical masks instead.
Illogical - If N95s don't work unless prof. fitted, how could surgical masks w/ big gaps work better? 1/
2/ The chart & thread here gathered by @akm5376 helps add perspective. Yes, a professionally fitted N95 provides tremendous protection! But even a un-fitted N95 is better than almost anything else, b/c the filtration is great & fit is already good.
3/ This is a nice thread by @claire_horwell on the differences between surgical masks and respirators.
(BTW, Prof. Horwell has been on a tear lately with a great OpEd & a number of great threads - worth following!)
Read 6 tweets
Dr. Alex Huffman Profile picture
17 Dec 21
Another good study simulating effects of masks, HEPA cleaners, ventilation in a small meeting room. By NIOSH team incl. Lindsley, et al.
mdpi.com/1999-4915/13/1…

🔸 Masks reduced aerosol by 50% +
🔸 Additive further exposure reduction w/ any combo of HEPA, ventilation
Summary 🧵
2/ For reference, this is essentially the same NIOSH team that did some other really nice work on masks and air cleaners:
e.g.:
And:
3/ The experimental team here used one aerosol source (0.3 - 3 microns) and three recipients, in various combinations. They used a relatively small room (54 m3) with 2 ACH on low fan speed in order to simulate a realistic meeting-type room.
Read 12 tweets
Dr. Alex Huffman Profile picture
5 Dec 21
Nice mask study ~consistent w/ prev. results.
pnas.org/content/118/49…

"... face masks sign. reduce the risk of SARS-CoV-2 infection compared to social distancing. We find a very low risk of inf. when everyone wears a face mask, even if it doesn’t fit perfectly on the face." 1/🧵
2/ The authors perform "upper bound" analyses to get around complexities in modeling risk.

"We conclude that wearing appropriate masks in the community provides excellent protection for others and oneself, and makes social distancing less important."
pnas.org/content/118/49…
3/ I especially like this overview schematic comparing FFP2 (~N95) to surgical mask usage based on combos between two people.

Consistent with the old refrain "any mask is better than no mask, but masks with better fit & filtration protect much more."
Read 14 tweets
Dr. Alex Huffman Profile picture
2 Dec 21
The #Omicron variant has been found in Colorado, thx to thorough surveillance by @CDPHE.

Omicron cases now detected in three counties in the US. I live in one of them. Seems like a great*time to take both individual & collective responsibility to slow spread. How?
Short 🧵 Image
2/ Don't freak out. It's "not a time for panic, a time for caution." You have some indiv control over your COVID health risk:
✅ Vax + boost yourself & family
✅ Wear a tight-fitting, high-quality mask
When possible:
✅ Avoid crowded areas
✅ Move meetings outside
✅ Open windows
3/ Loads of resources on what high-quality mask to choose & the #COVIDisAirborne safety protocols that you can follow.

A couple example recent threads on #BetterMasks:
*
Read 10 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us on Twitter!

Like this author's thread?

Get emails when @HuffmanLabDU has new unrolls!

Check out other threads from @HuffmanLabDU!

Read all threads by @HuffmanLabDU

:(