Aerosol particle emission increases exponentially above moderate exercise intensity resulting in superemission during maximal exercise (2 W/kg+).
So spin class outbreaks weren't caused by droplets aerosolizing after hitting the bike's flywheel? [sarc]
pnas.org/doi/10.1073/pn… October 2020:

https://twitter.com/DavidElfstrom/status/1315491534062710784?s=20&t=rg5IHgv2FgWKWnNwadrdeQ

When your board of health hires an unqualified MOH who can only be Acting, you get a minimizer who ignores the 51%-80% prevalence of Post-Acute COVID-19 Syndrome and recommends treatment of chicken noodle soup and ginger ale. simcoereformer.ca/news/local-new… (May 4, 2022) Post-Acute COVID-19 Syndrome is no picnic. Link to PDF from Public Health Ontario: publichealthontario.ca/-/media/Docume…

Welcome to Strausslandria, Ontario, where apparently “COVID was 10x more deadly than the flu... Today, flu is more deadly than COVID on average because our population is so highly vaccinated” /1 @JacobShelley norfolktoday.ca/2022/05/02/moh… Flu is now more deadly than COVID? Where's your reference for that, Dr. Strauss? Compare with “the mortality risk of COVID versus flu is likely greater than 24 times” (h/t @DGBassani @LadyScorcher) /2

https://twitter.com/danielgoyal/status/1519985415138250753?s=20&t=EGaCdJa9htN7gNKVv36pBg

Will Dr. Conly complain that today's award overstates his influence? After all, he complained to the CBC ombudsman in part because it described him as “An influential Canadian doctor and top adviser to the WHO” in reporting his controversial views of N95 respirators.

https://twitter.com/DFisman/status/1503388996671574023

Dr. Conly is the primary & corresponding author of WHO commentary article stating "SARS-CoV-2 not airborne to any significant extent, respirators offer no advantage & may result in unintended harms" aricjournal.biomedcentral.com/articles/10.11… /2

The Levoit Core 400S is a quiet and economical air purifier. I bought two of them for the kid's bedrooms and put one through some tests.
TLDR: Recommended! No conflicts of interest, this is self-funded. @LevoitLifestyle /1 @LevoitLifestyle The Levoit Core 400S is compact. There is an app to control units from your phone over wi-fi (the "S" indicates "Smart"). The sleep mode automatically turns off the display. It is quieter than my laptop in sleep mode. /2

The Ontario Energy Board has proposed an optional enhanced time-of-use price that would see residential/small commercial pay just 2.5¢/kWh overnight to encourage EV charging and battery storage, in return for a peak rate of 10x, or 25¢/kWh. /1 news.ontario.ca/en/release/100… With behind-the-meter battery storage and PV panels, along with increasing carbon price on natural gas, this could finally tip the balance in Ontario from gas towards heat pumps, ushering in cost-effective low carbon home heating and cooling. /2

Thread on why a typical building may be safer in spring and fall than any other time of the year:
Mild temperatures during the shoulder seasons result in the highest outdoor air change rates compared to winter and summer: /1 This is because of the economizer function on HVAC equipment. Due to solar gains and heat from people and equipment, it's warmer inside than outside. If the outdoor air is cooler than inside, use it instead of running mechanical cooling (air conditioning). /2

The next time someone denies the use of a portable air cleaner in a classroom on a (false) basis that it might spread infection by moving air, or interfere with the HVAC system, show them this paper. @amandalhu @sameo416 (HT @Poppendieck).
onlinelibrary.wiley.com/doi/epdf/10.11… /1 When determining the amount of outdoor air provided to a space, ASHRAE Standard 62.1's Zone Air Distribution Effectiveness factors to account for the inefficiency of air delivery and mixing to provide outdoor air to the breathing zone. /2

Insufficient ventilation at arena causes fog in the stagnant air over the ice between the plexiglass. CO₂ rose constantly without end until intermission, when we left, at 2000 ppm.
Great show! We wore our respirators, few others did. Some coughing behind and beside us. Dew point was approximately 4.5°C

The power was out this weekend so I decided to reclad the ELFSTRÖM in final permanent form: /1

https://twitter.com/DavidElfstrom/status/1429526273009889286

I used vinyl adhesive shelf liner to wrap the box. Still using painter's tape to mount the filter - makes it easy to change the filter and won't ruin the vinyl adhesive pattern. The filter gets sucked on when running anyway. /2

Highly recommended! Detailed summary of the main engineering controls for airborne infection control to reduce transmission indoors:
#Ventilation #Filtration #UVGI
👇

https://twitter.com/CathNoakes/status/1488639015507144708

#DoAllTheThings! Implement multiple engineering controls to reduce airborne infection and improve indoor air quality
#Ventilation
#Filtration
#UVGI

Having a CO₂ meter with visible display can enable an educator to be a manual version of a demand-controlled ventilation system, with control over the indoor environment using windows (Source: Di Gilio et al 2021, pubmed.ncbi.nlm.nih.gov/34224708/) #COVIDCO2
HT @Billius27 @Billius27 If a CO₂ display was in my daughter's mechanically ventilated classroom, her teacher might have opened the windows, or moved to another room after seeing rising levels. Principal: waiting for parts to repair the HVAC system. Daughter developed common cold symptoms 48h later.

Very exciting news on the #corsirosenthalbox front! @CorsIAQ & @CappaSnappa thanks for the (Elfstrom 2021) reference, it made my day! Some comments & questions follow: /1

https://twitter.com/CappaSnappa/status/1481049117736505351

"AHAM recommends that CADR is 2/3 of floor area" Yes, it's floor area = 1.55 x sqft. That's for 8' ceiling with 1 ACH residential outdoor air exchange, described in Annex E of AHAM AC-1 2020: /2

The air cleaner purchased by @nseducation for schools has a Clean Air Delivery Rate almost HALF of a common retail unit and may create secondary products by reacting with gas phase contaminants in a poorly ventilated room using photocatalytic oxidation #nspoli /1

https://twitter.com/MWES_School/status/1480586633867149324

As seen in the photo, it's not running on its highest setting. For #ventilationequity in non-mechanically ventilated classrooms, should be a min 15 CFM per person, or 375 CADR for 25 people, AND at an acceptable noise level. How many per classroom? #DoTheMath! /2

My wife & daughter traveled to @sickkids @SickKidsNews today for an appointment.

Several lapses occurred at screening. Most egregious:
They were made to remove their CA-N95 respirators for the blue surgical mask, shown below.

Let's go through all of them: /1 Your policy is to protect everyone, especially those at higher risk of COVID-19. How is downgrading masks consistent with that? What is the "right" amount of protection, anyway?
My wife and daughter were NOT offered the option of masking overtop. /2

Swiss study finds SIX TIMES the cases in poorly ventilated classrooms (those with over 2000 ppm CO₂) compared to better-ventilated ones. #COVIDCO2
#Ventilate2Educate #COVIDisAirborne
H/T @SamJCauston
swissinfo.ch/eng/society/st… More details on the Swiss CO₂ classroom study here: empa.ch/web/s604/covid…

While #Ventilate2Educate is geared towards schools, we can #Educate2Ventilate with simple directives for small businesses & organizations. Simple low-cost changes can make for an enormous indoor air quality improvement. Low-rise small commercial buildings are everywhere.

https://twitter.com/DavidElfstrom/status/1468957829851537416

These simple ventilation actions and more are described on the CDC's Ventilation in Buildings Page: cdc.gov/coronavirus/20…

Uh oh @GEDSB. My daughter's classroom was doing well in the fall with CO₂ levels below 800 ppm, so I stopped sending the logger. After my presentation last night with @DFisman, I decided to check it again. #COVIDCO2 /1 This is a school with full mechanical ventilation. This room is centrally provided so air is shared with other classrooms.
Filters have NOT been upgraded to MERV-13 or better.
HEPA is only in the rooms required by the province. Not in this classroom. /2

https://twitter.com/normsworld/status/1468021363172642817?s=20

Genome sequencing analysis shows spread of new variant in HK in hotel quarantine between suites across from each other when the air flowed to the corridor. Here we go again—no amount of positive pressure in the suite is acceptable. /1
h/t @nzm8qs news.gov.hk/eng/2021/11/20… If there is a 5 Pa positive pressure difference between the suite and the corridor, air will shoot out under the door continuously at an average velocity of 2.1 m/s (higher in the centre). No open door required. For a 10 mm bottom door gap, that's 19 L/s (40 CFM) of flow /2

#corsirosenthalbox flow tests for Lasko 3733 and 3M Filtrete 1900 20x20x1 filters.
Shroud optimization: 20 cm radius (15.75" diameter) /1 Effect of shroud size on outlet flow. Having a shroud is important, but don't stress over it. Without it, air flows backwards at the corners instead of through the filters. /2

Canadian Aerosol Transmission Coalition calls on federal party leaders for stronger, consistent COVID-19 protections:
1⃣Messaging on aerosol transmission and airborne protection,
2⃣clean air ventilation standard,
3⃣HEPA filtration, and
4⃣respiratory PPE. /1 Remember the prescient quote by the late Justice Archie Campbell, head of the 2003 SARS Commission:
📢“If we do not learn from SARS and we do not make the government fix the problems that remain, we will pay a terrible price in the next pandemic” /2