1/ Since start of the pandemic there's been one obvious and absolute truth. COVID-19 is an airborne infectious disease. As such, to reduce chance of infection and community spread we must significantly reduce the amount of virus-laden aerosol particles that we inhale. Period.
2/ That was true every second of every day before vaccinations, and while vaccinations are critical for reducing severe outcomes of infection, we should still be doing everything possible to reduce our inhalation dose of virus-laden aerosol particles. The steps are simple, folks.
3/ Wear a high-quality mask (e.g., KN95 or N95) at all times while indoors w/ others outside your own family.

Avoid indoor spaces where people are not wearing high-quality masks or masks at all.

Where one has control, ventilate to a much greater degree.
4/ Where one has control, increase effectiveness of filtration in HVAC systems (to MERV13 if possible) and/or use appropriately-sized HEPA filtration systems or DIY air cleaners - cleanaircrew.org/box-fan-filter…
5/ Lowering your inhalation dose lowers your probability of infection and, thus, lowers the extent of community spread if the majority of others do the same. High quality mask, avoid non-essential high risk environments, ventilate, filter. QED
6/ A simple message that should have been repeated for much of the past two years on a daily basis by those the public looks to for guidance.

It’s not rocket science. It's not a Rubik's cube. It's simple, folks. Just do it!

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More from @CorsIAQ

5 Jan
1/ Reducing respiratory aerosol particle concentrations in dorm rooms.

I have heard from parents who have children returning to dorms at universities across North America. The #corsirosenthalbox can help with these situations a lot! Really a lot, folks. read on.
2/ 8 hours unmasked while sleeping each night w/ 2 or 3/room should be a concern regarding infection, not to mention being poorly-masked while studying with others in the room.
3/ Increasing ventilation will help to reduce respiratory aerosol particle concentrations to the extent it is possible, but will be limited by system constraints or inoperable windows.
Read 8 tweets
1 Jan
1/ Some thoughts spurred by the guidance below

6 eACH (ventilation + filtration) is somewhat arbitrary, but a reasonable guidepost. Keywords here are "at least." The allusion to 95% removal of contaminant in 30 min is a bit deceiving. It ONLY relates to after source is removed. Image
2/ For a well-mixed indoor air space, an increase in eACH from, say, 2/hr (unfortunately not untypical for K-12 classrooms) to 6/hr yields a maximum decrease in indoor aerosol concentration of 67% and not 95%. Starting at 3/hr = max of 50% reduction w/ increase to 6 eACH.
3/ And the net benefit is particle size dependent, as particle deposition to surfaces is a third sink (removal mechanism) that adds to removal by ventilation and filtration.
Read 18 tweets
31 Dec 21
1/ The governor's words might be turned on those making such absurd statements. Inhalation of aerosols that contain the SARS-CoV-2 virus causes COVID-19. Right-sized HEPA air cleaners can be effective at reducing aerosol concentrations in classrooms.
2/ It is one important intervention amongst others (vaccines, masks, ventilation, testing) & plays a magnified role when significant increases in ventilation are not possible, when children have masks off, and/or some are not vaccinated. But it provides benefit in all scenarios.
3/ There have been dozens and dozens of peer-reviewed papers in high quality journals by high quality researchers that reinforce the value of HEPA filters for lowering indoor aerosol levels, even during the past two years and in the context of COVID-19.
Read 7 tweets
23 Nov 21
1/ With COVID-19 on the rise (again). Remember, the SARS-CoV-2 virus is transported by respiratory aerosols. INHALATION of aerosols is the dominant transmission pathway. Many of us have not wavered on this fact since early in the pandemic. It's about inhalation dose, folks.
2/ Since the dominant pathway is INHALATION of virus-laden respiratory aerosols, then reducing inhalation dose of these particles or inactivating viruses in the particles is the answer to reducing infection (pre- or unvaccinated & even vaccinated breakthroughs).
3/ Science & engineering gave us all of the tools we need to drive this pandemic into the ground. Vaccinations are a gift handed to us on a silver platter. The rest is not rocket science. The rest should be common sense.
Read 7 tweets
29 Oct 21
1/ A Quantitative Risk Estimation Platform for Indoor Aerosol Transmission of #COVID19 (Open Access paper)

Some Cliff Notes in thread below.

2/ This paper offers a platform that is somewhat more mechanistic than traditional risk estimates for airborne infectious disease. It includes ability to include aerosol size distributions & emissions from infected individuals + particle fate mechanisms indoors.
3/ Insertion of control options (increasing ventilation, masks, filtration) in single zone systems can be employed. The model predicts particle deposition in the respiratory system of receptors & converts these to total volume of particle deposition.
Read 7 tweets
21 Oct 21
1/ Indoor Air Quality in Schools
Some slides from a presentation on indoor air quality in schools a decade ago. It contains reference to what I thought were important/insightful papers at the time. A lot more slides than shown here. Will post at corsiaq.com
Read 18 tweets

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