Build a Do-It-Yourself Air Purifier for About $40

Michigan Medicine · 2.3M views · 2011 · 3:40

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Home, DIY & practical skillsMedicine & infectious diseasetutorial

Why Hacker News recommends it

HN people link it during wildfire smoke and air quality threads as a practical, cheap fix, though a few doubt how rigorously its effectiveness was shown.

What it is

A University of Michigan Medicine demonstration of building a cheap DIY air purifier from a box fan and a HEPA or high-MERV filter using hardware-store parts. It explains why this helps against dust, smoke and viruses and ties it to local air quality readings.

Recommended by 5 HN commenters across 4 different months, 2012 to 2022.

What Hacker News said

Strong rec polyfractal · 2012-01 · on “Ask HN: Does anyone use something to monitor air quality in their workspace?”

If you are worried about particulate, you can build one of these: [this video] I built one for my room because my previous tenants had cats, which I'm allergic to. Even after steamcleaning our apartment I was chronically congested. Built one of those purifiers and a few days later most of my symptoms are gone. It's been about a month now and the filter is noticeably soiled.

Recommends dublinben · 2020-01 · on “A small DIY air purifier”

Here's a video from the University of Michigan showing just how effective these cheap DIY air filters can be: [this video]

Recommends shard · 2020-09 · on “At JPMorgan, productivity falls for younger employees at home”

If this is because of high PM2.5 concentration (due to wildfires or otherwise), I suggest building a DIY air filter, such as the one in the video here: [this video] When the Air Quality Index shot up to ~150 in my area (you want to keep it below 100, preferably below 50), I went to Home Depot and bought box fans and furnace filters and built my own. You can check the air quality in your area on this site: [LINK]

Recommends Qub3d · 2020-09 · on “Smoke has caused temperature forecasts to go crazy”

The University of Michigan made an instructional video showing how you can easily make an air purifier out of a box fan and a HEPA-rated furnace filter for $25: [this video] It won't be as good as a purpose-built machine, but it will be far better than nothing at all. TheWirecutter found it reduced particulate matter in a room by 87%, if you do it right. They also make clear important caveats about this method -- in short, this works in a pinch, but probably should not be used in place of a purpose-built filter if you want one for year-round use. [LINK]

Recommends thomas · 2020-12 · on “Experiments on a $50 DIY air purifier that takes 30s to assemble”

Yeah, same thought. Something like the Coway air filter ( [LINK] ) regularly sells for under $200, and it is going to be much quieter than this option. It also has been tested fairly extensively from what I've seen, it's EnergyStar approved, etc, and it has a built in sensor. It doesn't look too bad either. But I understand the point, especially in times when you can't find a purifier. Also, good video on all this: [this video]

Cites vymague · 2018-03 · on “Cleaning sprays have an impact on lung health comparable to cigarettes”

But I thought it has been shown putting simple furnace filter on a fan is good enough. [this video] Are you talking about other filters to filter the larger particles, and carbon filters? Because aliexpress sell them too.

Cites meesterdude · 2018-10 · on “Air pollution linked to “huge” reduction in intelligence”

I know a certain framework creator that will be all over this - and has been vocal on twitter about it. I went looking, this seems like a pretty good air quality monitor: [LINK] (~$400) There are cheaper ones too; but do your research, as accuracy (and ideas about what constitutes accurate) can vary from manuf. to manuf. [LINK] also apparently, a box fan + filter ain't so bad. [this video]

Cites bryceacc · 2021-09 · on “Monitoring my home's air quality with AirGradient's DIY sensor”

[this video] you just put a fan filter on the back, you can increase the amount of filters to not hurt the fan motor as much by making a triangle config or fan on top of 4 filters in a cube. fans are for air throughput not static pressure so real air purifiers have squirrel cage blowers