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6 Feb, 8 tweets, 4 min read
CBC Marketplace and UofT's Dr Jeffrey Siegel tested 3 samples of 5 models of air purifier, including the DIY box fan with MERV-11 filter, which was better than the Dyson #filtration cbc.ca/news/business/…
The Marketplace/UofT tests did not consider how loud the air purifier is on its highest setting, which can be a limiting factor for practical use.
cbc.ca/news/business/…
Also consider the Clean Air Delivery Rate per Watt of power. ENERGY STAR air purifiers are tested for both.

Link: energystar.gov/productfinder/… Screen capture of web page
In the ENERGY STAR tests the Blue Air models are at the top with 13.7 CADR per Watt while the Dyson models are near the bottom at 2.4 CADR/W, so not only are they expensive to buy, they are expensive to operate
A reminder that #filtration and #ventilation are important for #IAQ but, so is source control. Don't put "stinky things" in your home.

Health Canada has a great resource on indoor air quality in the home

Link: canada.ca/en/health-cana… Infographic "Maintain and improve indoor air quality&qu
The DIY air cleaner: CBC's Marketplace tested the single-filter option.

Making a cube out of filters taped together provides higher flow, and the filters last longer. In this test @JimRosenthal4 also found a box fan with MERV-11 filters beats a HEPA texairfilters.com/its-all-about-…
More details on the Clean Air Delivery Rate from @CorsIAQ
Finally got around to watching the full 22-minute episode on CBC GEM. There's also some CO2 measurements, indoor air quality tests, and lots of good advice. Highly recommended!
cbcgem.app/EpRveQjsVvzvsc…

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More from @DavidElfstrom

David Elfstrom Profile picture
2 Feb
ASHRAE guidance on in-room air cleaners for reducing COVID-19 in the air (Jan 21, 2021)
@ShellyMBoulder
Link (PDF): ashrae.org/file%20library…
/1 IN-ROOM AIR CLEANER GUIDANCE FOR REDUCING COVID19 IN AIR IN
Stick to the basics of filtration. Beware of some technologies used by portable air cleaners: Ionizers, UV-PCO and other names may claim to remove or destroy contaminants but may convert them to other compounds that may be harmful
Link (PDF): ashrae.org/file%20library…
/2 In-room air cleaners may contain one or more technologies de
Good example of sizing a portable air cleaner for a classroom with a MERV-8 filter already present in the HVAC system to achieve 6 air changes per hour equivalent.
Link (PDF): ashrae.org/file%20library…
/3 Example of how to choose the right size: A 45 x 20 ft (14 x
Read 13 tweets
David Elfstrom Profile picture
31 Jan
New plain-language guidance for reducing virus transmission in schools using HVAC systems, by @HRAI_Canada

#Ventilatio, #filtration, UV, CO2 meters, humidity, portable air cleaners

Link (PDF):
hrai.ca/uploads/userfi… Reducing the Risk of Virus ...
HRAI has also reached out to school boards and Education Ministries Canada-wide to ensure decisions concerning #ventilation and #IAQ in schools are informed by the best available information.

mediaedgedigital.com/supplierinsigh…
Since children are likely to be the last to receive a vaccine, we must continue to push for indoor air quality funding.

The lasting benefits of better academic performance and reduces absenteeism of students & staff alike are worth it. /3
Read 4 tweets
David Elfstrom Profile picture
15 Jan
New preprint from J Lednicky & al: Isolation of SCV2 from air in a car driven by a COVID patient with mild illness. (Jan 15 2021).
While virus detected at all sizes, "Remarkably, viable virus was only detected in particles 0.25um to 0.5um)"
doi.org/10.1101/2021.0…
@jmcrookston
Automobiles are one of the worst places to be. Roll down windows, wear good, well-fitting masks, and especially use NO recirculation.
"The patient drove the car for 15 minutes w/windows closed and the A/C on, then parked it and exited, leaving the windows up and the air sampler running for an additional 120 minutes. Total collection time of 135 min to
sample 1.22 m3 of air within the vehicle"
Read 4 tweets
David Elfstrom Profile picture
14 Jan
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
Read 9 tweets
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

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