Duct-Taped $70 DIY Air Purifier Outperforms $1,000 IQ Air

New head-to-head test data from a citizen scientist finds that a simple, taped-together DIY air purifier effectiveness is higher than a market-leading Swiss air purifier, IQ Air. This data adds to an accumulation of data suggesting that effective air purifiers need not be expensive.

The Setup

The underlying science of purifiers is simple: purifiers are just fans and filters. This fact is so basic that it’s easy to test at home. Recently, an air system nerd in the US designed a souped-up version for $70 using a box fan:

DIY box purifier

It doesn’t even use fancy HEPA filters. Instead, it uses lower-grade furnace filters (called “MERV filters,” MERV 11 in this case). To measure how effective it was, he tested it against a $1,000 IQ Air:

IQ Air Purifier

He ran both machines for one hour each in the same 600-square-foot room (4,800 ft3). The tests started with approximately the same baseline number of particles in the room air. He even made the comparison biased against the DIY purifier by running it on medium, whereas the IQAir was on its highest setting (300 CFM).

DIY Purifier Effectiveness Test

Using a Lighthouse 3016 laser particle counter to test for tiny 0.5-micron particles, he tracked the percentage of particles removed over the course of an hour.

Lighthouse 3016 IAQ Monitor

Over that hour, the DIY purifier removed more particulate than the IQAir.

IQ Air effectiveness VS DIY purifier

(His data and methods are available here.)

Do try this at home!

Bottom Line:

Purifiers are just fans and filters. Price does not equal effectiveness. 

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P.S. Entirely Reasonable Skepticism

1. Yeah, but it’s probably loud as hell

Maybe that DIY purifier works, but it’s probably got some major downside, like it’s incredibly noisy, right? Just the opposite! The IQAir was actually louder than the DIY purifier. But since it is a DIY, noise levels can vary a lot between machines.

DIY Purifier Noise Test Comparison IQAir

Of course, spending $1,000 does save you from the labor of taping filters to a fan.

2. But the IQAir gets the really small particles, right?

This is a marketing myth. All fiber filters–even MERV filters–capture nanoparticles. Data shows it works even for N95 masks.

MERV Filters Capture Nanoparticles

We can see the same pattern in this DIY test data if we look at the hardest to capture 0.3-micron particles. The DIY purifier reduced the concentration of these particles in the room by 79% versus 72% with the IQAir.

3. Maybe this test just cherry-picks the most expensive air purifier to compare to?

Sure, the IQAir is probably the most egregious example of an insanely expensive purifier out there. So what happens if we include a fuller range of purifiers?

I analyzed four different sources of open-data tests of air purifiers and found similar results. For example, the DIY Cannon achieved the same effectiveness as the Blue Air and the Philips purifiers:

air purifier effectiveness price product comparison

Thus, it’s not just an IQAir phenomenon. High price tags for purifiers seem to mostly benefit the companies, not the buyers.

Read More: 4 Things to Know About the Corsi-Rosenthal Box DIY Air Purifier

How I Protect Myself

Smart Air is a certified B Corp committed to combating the myths big companies use to inflate the price of clean air. Smart Air uses the simple fact that air purifiers are just fans and filters to create no-nonsense purifiers, that remove the same particles as the big companies for a fraction of the cost. Only corporations benefit when clean air is a luxury.

Smart Air purifier more powerful cost less than other big brand air purifiers like blue air iqair

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5 thoughts on “Duct-Taped $70 DIY Air Purifier Outperforms $1,000 IQ Air”

  1. I did my own experiment where i put cheaper MERV 8 filters on the inlet side of the fan and Merv 13 on the outlet side. definitely is a lot larger, but it’s dramatically more quiet.
    honestly, the fact that we can leave it on 24/7 w/o the annoying noise makes it way more effective because before my kid would turn it off after 2 hrs because of the noise and we wouldn’t remember to turn it on, often until the air quality got noticeably worse.
    it is quieter than any purifier i used until i tried the SA600, which is definitely the most quiet purifier i’ve found.

  2. Would be curious what you think of this personal experience to maybe go a little deeper into why the hyperhepa of IQ air might be useful. I had a moisture problem when a renter left the hose on for 3 days at the foundation of the house. Ended up the floors in the Laundry and bathroom were plywood underneath and had lots of mold. I was reacting strongly to the mold so my friend lent me his $650 Blueair (regular hepa), but it didn’t to make a difference with my door closed and it on high. So he then lent me IQ air which I put on high and in about 10 minutes started to feel better. nose stopped running, eyes stopped itching. I know mold spores are supposed to be big but maybe they release a mycotoxin that is much smaller? One anecdotal argument for the more expensive hyperhepa.

  3. I’m curious about the impact of humidity on HEPA filters. There is some literature showing that HEPA filters might lose effectiveness completely in high humidity. These days we get 90%+ humidity through the dense foggy nights in Delhi and I wonder if the filter loses its utility in such conditions. Any tests or data out there on this? Thanks.


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