Thread by @HuffmanLabDU

🧵1/ The #CDC update today (2/26) on "Ventilation in Schools and Child Care Programs" looks like good progress.

Details on #ventilation, #filtration, #bettermasks, w/ helpful links. Seems they're listening to @kprather88 @j_g_allen @CorsIAQ and others?
cdc.gov/coronavirus/20…

2/ The relatively short #CDC page seems to have more succinct, yet clear #K12 guidance & connection to other pages of support.

Though I admit, I haven't digested yet fully. What are your takes? (also e.g. @jljcolorado @linseymarr @ProfCharlesHaas @Don_Milton @ShellyMBoulder)

3/ I was pleased to see early mention that "Wearing a well-fitting, multi-layer mask helps prevent virus particles from entering the air or being breathed in by the person wearing the mask."

(BTW, need for good fit implies aerosols)

Links (twice) here:
cdc.gov/coronavirus/20…

4/ The new #CDC doc then goes on to say (w/ various specific tips & links):

* bring in "as much outdoor air as possible"
* ensure HVAC settings are maximizing ventilation
* filter and/or clean the air
* use exhaust fans
* open windows in transport vehicles

5/ I was happy to see specific mention at least to "consider":

* portable air cleaners that use high efficiency particulate air (HEPA) filters, and
* ultraviolet germicidal irradiation (UVGI)

@polsiewski
BTW, if you're looking for HEPA filtration, see:
docs.google.com/spreadsheets/d…

6/ And the bit about opening windows on transportation vehicles is important too. I think this is an overlooked area & where easy measures (e.g. cracked windows) can make a huge impact (for school or any transport).

E.g. some simple modeling by @CorsIAQ:

https://twitter.com/CorsIAQ/status/1246323018780930048

7/ Though "recommendations" that have no teeth are still going to be met by some communities who "feel" differently or who don't seek expertise to implement changes. Need to keep advocating for communities to put *good* preventative measures into practice.

https://twitter.com/CorsIAQ/status/1364689330246098945

8/ For example, there are lots of well-meaning administrators who will buy products made available.

One tip: Don't rely on plexiglass barriers to prevent airborne spread. Small aerosol particles flow around like smoke.

https://twitter.com/HuffmanLabDU/status/1360841578852458497

9/ Another tip: Put more resources into cleaning the air than cleaning surfaces. Evidence suggests the spread is more strongly driven by airborne aerosols than surface contamination. Buy HEPA filters, not air foggers.

Nice article by @dyanilewis
nature.com/articles/d4158…

10/ Yet another tip: Buy & mount #CO2 sensors for ~$150 each as a real-time measure of how well ventilation is matched to the occupancy in your rooms (basically a proxy of "rebreathed" air, or how much air from someone's exhale is now in your lungs).

https://twitter.com/HuffmanLabDU/status/1362906731685142528

11/ Also lots of good data emerging on the efficacy of #HEPA filtration in settings like schools. See link above for a guide to choose the right type of air filtration for your needs. But rely on the filtration, and don't buy with extras like ionization.

https://twitter.com/HuffmanLabDU/status/1359893171023478785

12/ As far as portable, in-room portable #filtration, one option is to build relatively inexpensive #DIY options for ~$40:

https://twitter.com/HuffmanLabDU/status/1359893190791233536

13/ But along w/ ventilation & filtration, don't forget critical strategies of mandating good, tight-fitting masks and physical distancing.

Indoor lunch time is especially risky, b/c masks are off. See guidance e.g. by @j_g_allen et al via:
schools.forhealth.org/risk-reduction…

14/ Loose-fitting masks allow aerosols to flow around through gaps. High-quality, tight-fitting masks control the source of infectious aerosols.

For more motivation & basis for updating your mask see🧵 e.g.:

https://twitter.com/HuffmanLabDU/status/1357816930569129985

15/ Investing in the improvement of indoor air quality in classrooms & #K12 schools will have strong, positive benefit not just during respiratory virus pandemics, but during all other times as well. Now is the time to listen to experts and do it right.

(I meant to add in somewhere that the CDC update doc was HT @Concern14923094 & @DocJeffD, so Thx!)

16/ One addition to points above about mitigation strategies against airborne infection in schools -- see this *very* cool @nytimes aerosol emissions #visualization, also w/ windows, HEPA filtration, etc. (and an augmented reality view).

HT @Poppendieck
nytimes.com/interactive/20…