The PC Fan #CorsiRosenthalBox

I'm now a convert. PC fans from now on. I built two PC fan CR boxes and I'm addicted. Using PC fans might be the most important innovation to portable air cleaners since the invention of the original CR box. These are unbelievably quiet.

I think PC fans are the future of portable air cleaners. Noise is the problem and these are the solution. For those who don't want to completely DIY it, you can buy the frame and instructions from @cleanairkits . @robwiss has been testing these and providing the data on twitter.

"Standalone HEPAs or Corsi-Rosenthal boxes are a quick way to lower the risk of inhaling SARS-CoV-2 virus. Filtering the virus out of the air reduces the chance of inhaling it---simple logic. The other option is to filter/trap it with a mask before it is released or inhaled."

3M tested the Corsi-Rosenthal Box with the same rigor it applies to its Filtrete brand of products and found the C-R Box “performs exceptionally well in its ability to capture unwanted airborne particles, including viruses," says Kelsey Hei, a 3M application engineer.

“A C-R box uses MERV-13 filters, which can only remove 60% to 80% of those particles, (but) the fan on the C-R box is much bigger and can clean more air,” says Joseph Fox, chair of the indoor air quality advisory group with the Ontario Society of Professional Engineers, who works with schools on HVAC issues. “All you care about in the end is the total rate at which the air is cleaned. So, what the C-R box lacks in efficiency, it makes up for in airflow.”

Many exciting innovations have emerged in the last two years alone. Once it is clearly acknowledged the virus is airborne, it becomes a very fixable problem. People will shift from cleaning surfaces to cleaning indoor air where we spend 90% of our time. This has huge positive health ramifications beyond COVID-19 by reducing the spread of all airborne pathogens, pollutants including wildfire smoke, and other asthma-inducing aerosols.

To lower inhalation dose of virus-laden respiratory aerosol particles (a major key to suppressing the mortaility and mobidity associated with COVID-19) the three Rs must be advanced from where they are now. Remove, Reduce, Remediate.

Appropriate combos of Remove, Reduce, & Remediate are what many of us called layered risk reduction (or layered inhalation dose reduction) back in Spring 2020. Not rocket science. For those who still care about reducing the spread of COVID-19, it all still applies, folks.

"I am thrilled to be part of something that is so accessible to people around the world, helping to protect children in school and families in their homes, all the while inspiring children about the power of STEM."