Clean air is something you don’t think about until you need it
I bought a 3M Respirator with P100 filters years ago when we used to have two cats and I was the one cleaning the litter. Kicking up cat litter and breathing it in can cause Toxoplasmosis.
This was around the same time I became a parent so I started thinking about my child. We have a gas stove and water heater, so thinking about particles in the air and her being exposed to the litter got me doing a lot of research on detecting combustion particles.
Understanding the problem
There are many different sensors on the market, but many don’t detect Volatile Organic Compounds (VOCs) or the microscopic particles that cooking can give off (PM2.5). I decided to start by purchasing an Awair air quality sensor after researching all of the different models.
For a while that was it. I was consistently using a respirator for the cat litter and the air quality sensor would occasionally compel us to open windows and turn on a fan (usually when cooking). I also occasionally do woodworking and electronics soldering and so was happy to have a respirator available for that as well.
Then 2020 happened…
In the early days of COVID I turned to my trusty respirator until we were able to purchase more convenient face masks. The west coast wildfires hit and DIY box fan air filters became a topic of conversation. This wasn’t a new topic (Youtube) and has been driven by those suffering from severe allergies and amateur woodworkers (Youtube). There are even some really fancy ones you can build (Youtube).
As more research into COVID came to light, indoor air quality joined the discussion there as well since the same systems severe allergy sufferers and those with weakened immune systems depend on started to become important for schools and restaurants.
I’ll be honest that I didn’t give this issue much thought until I started stepping up my woodworking game. I got to the point where I needed to do some serious sanding and purchased an random orbit sander. All went well for a little while, until my wife started complaining about a thin film of dust covering everything in the basement, including the laundry. This affected my woodworking as well as I’d have to shower immediately after a sanding session and wood dust can cause quality issues with your woodwork projects.
Building my own DIY Box Fan
So with wood dust as my trigger and thinking about all the issues above, I once again caught the clear air “bug”. I saw some of the other DIY woodworking ones, but was suspicious that they weren’t as good as they could be. One thing I learned from setting up a dust collection shop vac is that there are many things that can restrict air flow and lessen the effectiveness of your system. After all, the reason HVAC air filters are pleated is because the layers of material restrict air flow. The pleats increase surface area and thus allow more air to get through.
There is also the issue of MERV rating. I wanted to purchase at least a MERV 11 filter, but would that be too much for a cheap box fan? At best it might move less air than it otherwise could. At worst it might stress the motor and shorten the life of the fan. It was then that I came upon a clip from This Old House (Youtube) and knew this was the solution I wanted.
Since my initial need is just wood dust, I decided to stick with MERV 11 for now. Most days this is hanging out in the basement and is only turned on when I’m sanding, but it can also be easily brought upstairs if we have an air quality issue. If I’m happy with it I plan to keep a stack of MERV 13 filters in reserve in case of an air emergency in the future.
This is just the beginning of my journey. I still need to integrate the Awair sensor into my smart home and I have some future smart home and IoT ideas in my head for managing bathroom humidity and automatically bringing in fresh air from the outside.