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14 Jan, 9 tweets, 6 min read
BREAKING! Ontario Society of Professional Engineers @O_S_P_E calls on the Ontario government @ONgov to IMMEDIATELY address the #airborne transmission of COVID-19 to help slow the spread.

Summary thread follows
/1
ospe.on.ca/featured/engin…
"OSPE and its engineers believe a key piece to our defence against this virus has not been properly addressed by the Ontario government - the need for proper #ventilation and air #filtration to stop the spread of the virus via #aerosol particles"
/2
"OSPE believes that airborne transmission is one of the main reasons why we are seeing so many outbreaks in schools and long-term care facilities across the province"
/3
"both World Health Organization and Public Health Agency of Canada have recognized the spread of COVID-19 transmission via #airborne #aerosol particles; however Public Health Ontario seems less convinced"
🤬
/4
"With outdoor temperatures dropping, many buildings have shut themselves off from fresh air that would have helped get rid of these particles. Instead, many buildings have closed HVAC systems that recirculate the same, potentially infected, air"
/5
"Earlier this year @ASHRAE_Journal published their report ASHRAE Position Document on Infectious Aerosols", noting that HVAC systems have a major effect on transmission of disease" Link to PDF: ashrae.org/file%20library…
/6 Screen shot of title with logo. ASHRAE Position Document on
"Other groups have already voiced their concerns to the government, and after careful consideration of the evidence, we are reaffirming our position" says Ontario Society of Professional Engineers
/7
theglobeandmail.com/canada/article…
" @O_S_P_E believes consulting with engineers, scientist, HVAC specialist and other experts in these fields should be done immediately in order to help the Ontario government adequately address this issue before more outbreaks occur"
/8
A sincere thank you to @O_S_P_E and fellow engineers for speaking out in the interest of public safety.

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More from @DavidElfstrom

David Elfstrom Profile picture
11 Jan
🇨🇦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
Read 4 tweets
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

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