Experiments using a Corsi-Rosenthal DIY air purifier box

Been a long time since I posted here, but I feel it's the best place for me to share this in length.

So on September 12th, 2022 my wife was not feeling well and had COVID-19 symptoms so she used a rapid test which turned out positive. We went into isolation mode, which BTW in a 2 stories house with 1 bathroom and 2 teenagers is not that easy. 

Anyway we limited the kids going upstairs, I did meal preps, and they ate in their rooms (no complaints here), I ate in the kitchen, and my wife in the living room (again no complaints here). We both wear masks, teenagers, not so much, but they stayed in their rooms anyway.

My second reaction to this situation was to build a Corsi-Rosenthal box to keep the air clean to protect the kids. So I bought parts for 2 boxes from Amazon:

By the end of the day, I was starting to feel like something was going on with me. Cold sweat, coughing. After a bad night, I tested positive on Wednesday...

The Amazon kit for my CR boxes came in on Wednesday, but I did not have the energy and only built one unit on Friday when I had a bit more energy.

I did not want to just power it up and not know what it was doing, so I took the CPU module I use for my co2.click sensors and modified the code for Model C to just dump the reading from a Plantower PMSA003I PM sensor every minute to my cloud server. Nothing fancy, just pipe delimited to the log. I would use LibreOffice Calc and/or GoogleSheet to view the data for now.

I then set it in the vicinity of the CR box and let it log for about 1h45m to get a baseline. And then turned on the CR box at low speed.

And I went for a nap as I had pretty much spent all the energy I had coughing, sweating, making, and coding.

After a short nap (yeah I was thinking about the data being sent to my cloud server the whole time), I went back down to my basement office and pulled the first set of data. I was immediately amazed at what I was seeing. The CR box within a few minutes had brought the particles levels down and way down:

I did shut off the unit the first night out of security (just to be sure, I do that with all new DIY electronics), but it's been running all day for 2 days now and the data I got is amazing.

For instance, on Saturday, September 17th at around 16h30 I saw a high spike in the particle count. I am not 100% sure what caused it, but I was outside enjoying fresh air and sun, my wife was sleeping, and the teenagers were in their rooms doing whatever teenagers do (play video games off course!).

The only thing I remember is that about that time my neighbour started doing his lawn with his gas-powered tractor and mower. I live far from any city type of activities, surrounded by wood and lake/river nearby, so it was not caused by city type of activities and no-one in the house was cooking.

This is just to say that Corsi-Rosenthal boxes are working, and they do a hell of an amazing job filtering out bad particles out of the air including, but not limited to COVID-19. The numbers prove it.

For those interested, the complete dataset is available in a GoogleSheet format here:



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