Share this page!

David Elfstrom Profile picture
Twitter logo
11 Jan, 4 tweets, 4 min read
🇨🇦EXCELLENT! Public Health Agency of Canada @GovCanHealth today (11 Jan 2021) releases a full pandemic #ventilation guide!

PROVINCES break out the #scicomm, update regulations, investigate ventilation in LTC, schools, & other congregate settings

Link: canada.ca/en/public-heal… Screen capture of web page titled: COVID-19: Guidance on ind
The new Public Health Agency of Canada #ventilation guidance references the Aerosol FAQ & work of @kprather88 @linseymarr @ShellyMBoulder @jljcolorado @ASHRAE_Journal & many others

FAQs on Protecting Yourself from COVID-19 Aerosol Transmission, link: tinyurl.com/FAQ-aerosols Screen capture of the top of the FAQs on Protecting Yourself
WHO recently issued guidelines for air changes per hour in long term care. Must check each facility. Can't repeat the Vigi Mont-Royal outbreak (faulty ventilation, 100% infection rate, 70 deaths)

• • •

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

Keep Current with David Elfstrom

David Elfstrom 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 @DavidElfstrom

David Elfstrom Profile picture
9 Jan
Published today (8 January 2021) Public Health Ontario's FAQ on Portable Air Cleaners and Transmission of COVID-19.

A good resource, and quite the opposite to what INSPQ released for Québec, also today.

PDF: publichealthontario.ca/-/media/docume… Screen capture of the top o...
Ontario's FAQ comes five months after @jljcolorado's 22-tweet thread on air cleaners, and earlier work by @ShellyMBoulder. Be ahead of the curve, follow them.
FOIRE AUX QUESTIONS - L’utilisation de dispositifs portatifs de filtration d’air et la transmission de la COVID-19 (PDF): publichealthontario.ca/-/media/docume… FOIRE AUX QUESTIONS L’utili...
Read 4 tweets
David Elfstrom Profile picture
3 Nov 20
Wow, this is what I've been advocating for Ontario school boards since August!

The School District of Philadelphia is measuring the outdoor air amount supplied by mechanical #ventilation of every room in every school. THREAD #onted
They use 15 CFM per person of outdoor air as the threshold.

Technically, ASHRAE Standard 62.1 is 10 CFM/person plus 0.12 CFM/sqft. If there are 18 persons in a 750 sqft room it works out to the same.

You can view the ASHRAE standards from this page: ashrae.org/technical-reso… Recommended healthy air flow in a classroom is 15 CFM per pe
Back in August, I recommended posting a sign on each school room:
Read 14 tweets
David Elfstrom Profile picture
2 Nov 20
I'm already seeing 6 Air Changes per Hour as a blanket number. However this depends on volume, or rather, the ceiling height vs floor area and occupancy. A rough guide might be:
12 ACH small volume (vehicles)
6 ACH average (office, classroom)
3 ACH large vol (arena, warehouse)
Houses and apartments are quite a bit different: ASHRAE has an entirely different standard just for residential #ventilation! Easier to think of per person amounts.

Try for 30 CFM per person for COVID-19 but no less than ASHRAE 62.1 Table 4-1a in ASHRAE 62.1-2019
Drat. I meant no less than ASHRAE 62.2

By the way, the relevant pandemic ASHRAE standards are available for free to view on their website, which I greatly appreciate. <glares at CSA>
Read 5 tweets
David Elfstrom Profile picture
20 Sep 20
BREAKING
CDC changes COVID-19 guidance, airborne is primary way the virus spreads, touching surfaces is NOT the main way. #Ventilation is important, as it goes beyond 6 ft and remains suspended in the air.
H/T @jljcolorado & @jmcrookston Comparison of text from archive.org showing difference betwe
Canada, you need to revise your guidance to be in line with science, known since February. Add breathing and inhalation. Minimize surface transmission. Add poorly ventilated spaces as risk factor, remains in the air and travels greater than 2m indoors.
canada.ca/en/public-heal…
One-stop must-read by the top aerosol scientists:
FAQs on Protecting Yourself from COVID-19 Aerosol Transmission
This document is frequently updated.
Shortcut: tinyurl.com/FAQ-aerosols
Read 8 tweets
David Elfstrom Profile picture
31 Aug 20
HVAC is trending in #Ontario.

Let's clear the air, #onted.

It should be immediate #VENTILATION, with filtration improvements, for a #SaferSeptember to buy us time, and Indoor Environmental Quality improvements (#IEQ), for the long term. Not generic 'HVAC'. Not "AC".

THREAD
We say we urgently need quality HVAC in schools (we do!) but HVAC is:

(H)eating the building,
(V)entilating using outdoor air, and
(A)ir (C)onditioning,
where AC = removing heat and moisture.

ALL classrooms have H and V, though often no AC.
In old schools Ventilation was provided naturally, using a chimney effect to cause negative pressure in the school, drawing outdoor air inside. It's unreliable, so these schools were later retrofitted with exhaust fans to force the air out. (if you find unrenovated, send pics!)
Read 20 tweets
David Elfstrom Profile picture
24 Aug 20
1/ #VENTILATION is a key factor in #SafeSeptember for #onted. In this thread I'll cover:

🔸My immediate 3 asks of @sfleece and @fordnation

🔸A suggested room-by-room assessment and implementation methodology

🔸Who to follow Photograph of a rusty rooftop classroom exhaust fan that was
2/ My immediate asks of Ontario:

1⃣ Update the Guide to Reopening Ontario's Schools to add #ventilation, currently absent. I recommend using Schools for Health: Risk Reduction Strategies for Reopening from Harvard School of Public Health schools.forhealth.org/risk-reduction…
3/
2⃣ Also update the Guide to Reopening Schools to reflect current knowledge regarding the relative importance of airborne transmission of COVID-19 compared to surface transmission.
Read 39 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 @DavidElfstrom has new unrolls!

Check out other threads from @DavidElfstrom!

Read all threads by @DavidElfstrom