Share this page!

Dr. Alex Huffman Profile picture
Twitter logo
11 Aug, 15 tweets, 11 min read
A 🧵 to counter some confusing messages about masks & wildfire smoke (1/x)

1. High-quality masks (i.e. #N95) best for both viral aerosol + #wildfire smoke
2. N95s readily available & should be used for both
3. But other masks can provide non-zero benefit
denverpost.com/2021/08/10/wil…
2/ The #CDC and #EPA both strongly recommend upgraded masks (respirators) like #N95 or #KN95 to protect against wildfire smoke. I totally agree (unless using something even better like N99 or elastomeric), b/c these filter the smallest particles very well.
cdc.gov/disasters/covi…
3/ But the #CDC also says not to use N95s, b/c they "should be reserved for health care workers." I totally disagree, as do countless others, b/c supply chain problems in 2020 have recovered in the US.

Follow @projectn95 & see resources to easily buy.
projectn95.org
4/ Furthermore, with the more transmissible Delta variant of COVID now dominant, we have to work harder (even if vaxxed) on airborne virus protection by using #BetterMasks, like N95s.

E.g., watch this important perspective by @mtosterholm.
5/ Why are N95/N99 respirators rec'd by CDC, EPA to protect against inhaling wildfire smoke? B/c smoke has really tiny particles that more easily pass through lower quality, looser masks.

Size peaks at 0.2-0.5 microns in this old paper by @gavinmcmeeking. agupubs.onlinelibrary.wiley.com/doi/full/10.10…
6/ And #N95s are rated to take out 95% (or 99% if N99) of particles at 0.3 microns (300 nm), which is around the peak of the smoke size distribution.

One of the best videos (~6 minutes) that explains how N95 respirators work is this one by @minutephysics.
7/ *But* #CDC also strongly implies that cloth masks do nothing to protect against inhaling smoke. This part is misleading.

Many non-N95 masks can still remove some fraction of even the hard-to-filter 300 nm (0.3 um) particles.
E.g., Morais et al.:
tandfonline.com/doi/figure/10.…
8/ Wearing an N95 or the best mask possible is important, BUT (wrt both COVID & wildfire smoke) ... any mask is still better than no mask.

Watch the whole interview (see thread below), for useful perspectives from @mtosterholm:
9/ Not only is the quality of the filter material important, but also the quality of the fit. If a mask sits only loosely on your face, viral or smoke aerosol enters through gaps. Use tight straps & nose clip.

Here's an old thread w/ info on #MaskFit:
10/ For example, here is a German study from Oct. 2020 by Drewnick et al. that shows that even a ~2% mask leak area could reduce filtration by ~50-70%.
tandfonline.com/doi/full/10.10…
11/ So yes, high-quality (N95) masks are great against #wildfire smoke, but an imp. 1st approach is to avoid the smoke or go to a cleaner indoor environment.

For details on how to get yourself some clean air, read this by indoor air quality expert @etgall
elliott-gall.medium.com/wildfires-and-…
12/ Masks (on your face) & filters (in room air) don't take out the nasty gases in the smoke, but they can remove the small particulates/aerosols.

Search #Boxfanfilter or #CorsiRosenthalBox for cool anecdotes on #DIY air cleaners.

13/ Also imp. that any particulate matter (i.e. wildfire smoke or urban haze) stresses & damages your lungs. That can make them more susceptible to respiratory infection. So ... protecting your lungs against smoke is ALSO helping to protect against COVID.
nature.com/articles/s4137…
14/ To help you make decisions related to #wildfire smoke episodes in your area, these are great and freely available tools. My favorite is the AirNow Smoke/Fire Map: fire.airnow.gov.

15/ So in summary ...

✅ Respiratory aerosols (COVID) & wildfire smoke bad for your lungs & health
✅ N95 masks are best against both
✅ Indoor HEPA or DIY air filtration also great
✅ But if in smoke w/o an N95, most masks still better than no mask

• • •

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
13 Aug
Feeling helpless as a parent, trying to work w/ school guidance based on @CDPHE rec's that are often vague or misunderstand aerosol science (i.e. no mention of #lunch air risk; says misnomer AGPs esp. risky)

Could *someone* here ask an airborne scientist?
covid19.colorado.gov/practical-guid…
The struggle is a circle: Colorado (@CDPHE) bases guidance on @CDCgov, which is still mo's behind & catching up to an accurate understanding of airborne virus spread.

School district guided by state. So to get local school to budge, need CDC to improve. So, as a parent ... ?
The best #CDC guidance I found (from Aug. 5 👇) on #school meals or #lunch is vague and doesn't get at the real problem -- which is that when people take off #masks (when eating, esp. when sitting really close), exposure increases.
cdc.gov/coronavirus/20… Image
Read 7 tweets
Dr. Alex Huffman Profile picture
12 Aug
Lots of questions about best #masks for kids at school. Practical answer: highest quality, tightest fit they will *wear*

No one answer, resources to consider as you look; short thread. #MaskUp #KidsMasks #MasksInSchools

(1/x) This by @CleanAirCrewOrg:
cleanaircrew.org/kids-masks/ Image
2/ Recommendations, with accompanying video + data on #KidsMasks by @masknerd.

Data: drive.google.com/drive/folders/…
Thread w/ links:
Video:
3/ Article by @zoermalin summarizing children's #KN95 masks:
nbcnews.com/shopping/welln…
Read 8 tweets
Dr. Alex Huffman Profile picture
11 Aug
This interview with @mtosterholm is 🔥. One of the clearest & most succinctly accurate 6-min summaries of where we are with Delta/COVID mitigation, masks, & vax (best part starts at 1:30).

#VaxUp #BetterMasks #N95 #MasksInSchools
A few quotes below. h/t @PPEtoheros, @citlanx
"This virus is an #aerosol. It’s transmitted in the air, just like we see with cigarette smoke. If you’re in a room and you have a covering on your face and you can smell* the smoke, then you know you’re also getting virus in there if in fact you had an infected person in there."
* (Editorial comment on the smoke smell comment. Aerosols in smoke come out as a concentrated plume, waft through the air, & build-up indoors. But the smell is from the gases & can go through masks, whereas aerosols are blocked. Good visual analogy, but it breaks down at smell).
Read 7 tweets
Dr. Alex Huffman Profile picture
22 Jul
I keep thinking about articles discussing importance of being both #VaxxedAndMasked. Some comments via 🧵. (1/x)

Data shows:
✔️ Vax safe & wildly effective
✔️ No vax 100% (think raincoat or sunscreen)
✔️ Masks very effective
✔️ Both help indiv & public health
✔️ Delta is a beast
2/ Through hard work we know:
✔️ COVID could spread by several routes
✔️ Airborne aerosols likely to be a critically important piece of that spread
✔️ We can reduce w/ masks, distancing, reducing #SharedAir
✔️ Vax reduces number & severity of infections
thelancet.com/journals/lance…
3/ So if the only factor (indiv or collectively) is to provide the best protection, the answer is clearly to #VaxUp ASAP & to still #MaskUp in crowds or indoors w/ anyone who is unvaxxed. Delta is dangerous & many not yet protected.
Read 17 tweets
Dr. Alex Huffman Profile picture
21 Jul
Why should vaccinated people wear masks? Seven points outlined by @Bob_Wachter in article by @amyjeangraff & in 🧵 with his reasoning below.

I'm still very careful about taking off my #N95 mask in mixed settings & support #mask mandates for schools.
sfgate.com/bayarea/articl…
1) The rate of breakthrough infections is small but very real.
2) The rate of breakthrough infections with delta is likely somewhat higher than with the original virus; this number is still being debated.
3) Delta might be more likely to lead to a serious infection than the original virus.
4) Though the chances of long COVID with a breakthrough infection seem to be low, there is no rigorous evidence on this & we certainly have seen mild primary infections cause prolonged symptoms.
Read 6 tweets
Dr. Alex Huffman Profile picture
21 Jul
Should you still wear a #mask, even if you're vaxxed?

Answer isn't just about science, but also your risk tolerance & philosophy of humans. Nice overview by @olgakhazan w/ (contrasting) comments below by Profs @linseymarr @cmyeaton @j_g_allen @ashishkjha
theatlantic.com/politics/archi…
"According to Rivers, the vaccinated should keep masking indoors in these places until children under the age of 12 can get vaccinated. 'I don’t think we should give up on mitigation until we can offer kids the same protection afforded to everyone else,' says @cmyeaton."
"Though your heart might not break for your local anti-vaccine conspiracy theorists, 2 - 4% of American adults are immunocompromised, which means the COVID-19 vaccines do not work as well for them. By masking, you are ... also protecting kids & the immunocompromised." @olgakhazan
Read 8 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 Become our Patreon

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

:(