$70 DIY Air Purifier Effectiveness Better than $1,000 IQAir

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. This data adds to an accumulation of data suggesting that the 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:

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:

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.

(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. 

Smart Air

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.

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, price is actually slightly negatively correlated with effectiveness in tests from the Shanghai Consumer Protection Bureau:

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

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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