Thread by @CorsIAQ

1/ COVID-19 Risk Reduction
Positivity rates are currently increasing significantly in many locations. Whether vaccinated (hopefully) or not, the risk of COVID-19 infection can be significantly reduced by lowering your inhalation dose of virus-laden respiratory aerosol particles.

2/ In indoor air quality parlance, that can be done by
* Source removal
* Source reduction
* Concentration reduction

3/ SOURCE REMOVAL
“If there is a pile of manure in a space, do not try to remove the odor by ventilation. Remove the pile of manure." Max von Pettenkofer (1858)

4/ I do not mean to draw analogies between piles of manure and humans, but von Pettenkoffer goes to the heart of "no source, no issue."

Test and stay home if positive. Stay home if you feel any relevant symptoms until you have a chance to test. Play it safe and protect others.

5/ SOURCE REDUCTION
Use high-quality, e.g., N95, masks to signif' reduce emissions from someone (maybe you) who is infected and also reduce inhalation of respiratory aerosol particles by those not infected, a double benefit that can lead to 99+% reduction in inhalation dose!

6/ CONCENTRATION REDUCTION
This means lowering the concentration of respiratory aerosol particles in indoor air given that sources do exist. Have outdoor meetings whenever feasible and reasonable.

7/ Outdoor dispersion of respiratory plumes is orders of magnitude > dispersion indoors.

If meeting outdoors is not possible, bring some of that outdoors in as conditions allow. Increase outdoor air ventilation where you have control (at home, the building you manage, etc.).

8/ The concentration of respiratory aerosol particles can be reduced by using right-sized HEPA air cleaners, a proven technology that can easily add to 2.5 to 3.5 or more equivalent ACH in many school classrooms, small apartments, rooms in homes, shared office spaces.

9/ #CorsiRosnethalBox es not only lower the concentration of respiratory aerosol particles indoors but the high flow rates can also lead to significant dispersion of respiratory aerosol plumes in close contact by adding significant mixing to indoor spaces.

10/ Based on published data, these devices can lead to 2 x the CADR of good $300 air cleaners for 1/4 to 1/3 the cost, meaning the addition of 5 to to 7 or more equivalent ACH to the spaces described above. Proof here: tandfonline.com/doi/full/10.10…

11/ Listen to @Don_Milton, @ShellyMBoulder and others about the benefits of appropriate germicidal UV technology. In this case the concentration reduction is not of virus-laden aerosol particles, but rather effective inactivation of viruses in those particles.

12/ None of this has changed during this entire pandemic. Lower inhalation dose of virus-laden respiratory aerosol particles. It's not rocket science, folks. Just do it!