Latest in my coronavirus series on facts and strategies for coping safely with COVID-19.
Check this out: a do-it-yourself air filter that I made myself for $100, vs the $300+ for commercial ones. People are making these “Corsi-Rosenthal boxes” and donating them to schoolrooms, churches, anyplace where people want to gather and you want the air as clean as is practical.
Watch as it cleans the air in my dining room, as measure by a couple of particle meters I got on Amazon. (Zero is absolutely clean; 12 is the desired limit for safe air.) (You don’t have to watch the whole six minutes – skip through it or speed it up.)
I’ll say more in subsequent posts but here’s the basic story:
- For virus defense, clean air is a must. Coronavirus rides on tiny particles, which can make you sick (or die) if they get in your lungs.
- In the past I’ve written about CO2 meters you can buy to check how good a place’s ventilation is. (Ventilation flushes stale and potentially dirty air out of a room.) Here’s one of my posts with links to others.
- Filters, on the other hand, remove particles that the virus might ride on.
This September 2020 post about filters includes the first Honeywell filter we bought for our home. (We have an idiot anti-science/anti-vax relative who must visit at times. We make her sit next to the filter with a mask on.)
Here’s the image from that post:
Since that time, some air quality nerd-professors named Corsi and Rosenthal collaborated with some others and developed a way of building your own filter, using stuff you can literally get from places like Home Depot. It works, it’s more efficient than the commercial filters (!), and costs way less. So now I get to update that image:
In a nutshell:
There are three strategies for air quality: source control, ventilation (“pollution dilution” – open a window), and cleaning (filtering).
- Getting others to wear masks is source control: you limit how much virus is likely to get out of them and into your air.
- CO2 meters check the ventilation, wherever you are. (I’ve been astounded that doctors’ offices often have mediocre ventilation.)
- Filters try to remove whatever pollutant might still be in the air. (That’s true for the filter on your face and for a room air filter.)
- Particle meters check the filter’s success. (I’ll say more about these meters in another post.)
- Here’s the definitive page on Corsi-Rosenthal boxes, with gobs of info and resources, on Clean Air Crew.
- If someone who wants a complete intro to the subject, I like the 8 minute This Old House video on that page
- Here’s an academic preprint assessing how well CR boxes work, compared to commercial filters.
- Here’s a lay article with 3 minute video on an Arizona State project to build them for schools
Sample tweets from happy people who made some for schools:
- for a day care
- high school students teaching middle schoolers to make them
- a thread about a box they named Gus (results after 1 month in classroom)
- Tweet from a “public school mom powered by coffee and righteous indignation” :-)
You can also check out my Facebook post (with video) from when I first made the thing.
I love it: grass roots public health at the community level. People helping people.
As I said, people aren’t making these “Corsi-Rosenthal boxes” for their dining rooms – they’re making them for places where people might be carrying virus droplets into the room, such as classrooms and churches. These “C-R boxes” are a do-it-yourself self-defense tool, based on real science that’s been validated by real air quality scientists. Citizen participation in public health. I love it.
More to come.