Yaneer Bar-Yam
Dustin D. Wind@yaneerbaryam For those who don't have money to drop on an expensive "official" device for air filtration, a Corsi-Rosenthal box can be a relatively-affordable godsend. Four furnace filters and a box fan, and it cleans air much faster than many "official" devices that cost 10x as much.
https://cleanaircrew.org/box-fan-filters/
DIY box fan filters – Corsi-Rosenthal box - Clean Air Crew
Also known as a Corsi-Rosenthal box, this DIY method of building your own air filter with MERV13 furnace filters and a box fan are an easy and cost-effective way to help clear indoor air from airborne virus particles, wildfire smoke, pollen, dust, and more! If you can seal a box, you can build one (or
@MySideIsHumanity I agree completely. Be aware that the relative filtration rates mean that at the time average level the Corsi-Rosenthal Box has to be 4X ACH to achieve the same level of filtration. So the 10X lower cost means that it is about 2.5X more cost effective.
Paul Briley 🇪🇺@yaneerbaryam @MySideIsHumanity
#corsirosenthalbox is legitimate way to clean air & is as efficient as HEPA air filtration & in most instances is quieter at doing it with higher CADR
https://news.3m.com/2022-02-24-3M-scientists-This-Corsi-Rosenthal-box-movement-is-legit?utm_term=corp-brd-en_us-ba-corsirosenthalbox-osm-mtpl-na-learn-is-feb22-na
#corsirosenthalbox is legitimate way to clean air & is as efficient as HEPA air filtration & in most instances is quieter at doing it with higher CADR
https://news.3m.com/2022-02-24-3M-scientists-This-Corsi-Rosenthal-box-movement-is-legit?utm_term=corp-brd-en_us-ba-corsirosenthalbox-osm-mtpl-na-learn-is-feb22-na
@paul_briley @MySideIsHumanity We should correct for the filtering efficiency. CADR is not a like for like comparison as we require a certain ACH for a particular room and that has to be combined with filtration rate (i.e. 80% compared to 99.97%. See other comments.
David Elfstrom@yaneerbaryam @paul_briley @MySideIsHumanity CADR is an experimentally tested particle removal value independent of filtration efficiency and reflects the equivalent outdoor air exchange rate. No further adjustments are needed to calculate the equivalent air changes per hour.
@DavidElfstrom @paul_briley @MySideIsHumanity Let's discuss so it will be clear. I sent my number by DM so we can discuss.
@DavidElfstrom @paul_briley @MySideIsHumanity
Please also clarify why we would need any particular filtration rate if this were true. For example why not 50% or 10%?
Clean Air Stars@yaneerbaryam @paul_briley @DavidElfstrom @MySideIsHumanity For infection control purposes there may be a lower bound of required efficiency where the additional mixing of air containing particles with infectious virions accompanied with inadequate filtering may increase the average risk to participants throughout the space. Eg Dyson with a HEPA filter but ~6% single pass efficiency due to ~15x flow multiplier
@cleanairstars @paul_briley @DavidElfstrom @MySideIsHumanity
We are on the same side. Speculative statements don't constitute science. Please provide information that would explain the different regimes and the behavior that connects them.
@yaneerbaryam @paul_briley @DavidElfstrom @MySideIsHumanity There is some protection for each occupant related to their distance from the emitter that would be a function of particle/virus concentration & airflow patterns plus time for viability decay (a function of time, humidity, temp, & presence of UV). Quantifying these in any meaningful way that adequately represents the variables present in each unique situation, is not going to be easy
@yaneerbaryam @MySideIsHumanity @paul_briley @DavidElfstrom Therefore it will not be straightforward understanding the impact that high mixing with low (inadequate) outside air or filtered recirculated air will have, or how we determine what “inadequate” filtration single pass efficiency actually is. It would be a continuum. Assuming same mixing, 0% filter efficiency with no outside air will increase *average* risk across the room, 99.97% filter efficiency will decrease risk.