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

New head-to-head test data from a citizen scientist finds that a simple, taped-together DIY purifier effectiveness is higher than a market-leading Swiss 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: … Read more

Dyson Pure Cool air Purifier Tower CADR Review

Dyson Pure Cool Air Purifier Review: Shockingly Bad

Dyson’s Pure Cool air purifier looks impressive. However a review of its clean air rating (CADR) reveals this filter does a poor job of providing clean air – the Dyson TP05 Pure Cool’s CADR comes in at just 164m3/hr. That means the Dyson Pure Cool air purifier out as much … Read more

how to choose best air filter air purifier guide

Four Steps To Choosing The Best Air Purifier

“What’s the best air purifier on the market?” It’s a question that many of us might ask. There are thousands of air purifier models to choose from, so how can you find the best air purifier that’s right for you? This article covers those steps in a slightly unorthodox way. What’s … Read more

Can Plants Filter Out PM2.5 Air Pollution From Our Homes?

Can plants be useful substitutes for air purifiers? Data shows that plants aren’t great at removing VOCs from the air. Despite a NASA study showing that some plants like ivy, spider plants, aloe vera and bamboo palm could reduce VOC levels, real-home data shows otherwise. But how well can plants … Read more

Do Air Purifiers Remove PM2.5?

When I was coughing through Beijing’s airpocalypse and thinking about buying an air purifier, I wanted to know something first–do air purifiers really remove PM2.5?     I wondered because I saw lots of air purifier tests on pollen, but pollen is generally 10 microns or larger, whereas I was … Read more

Measuring Air Purifier Noise

The new Cannon kicks butt (scientific definition of kicking butt), but it’s noisier than the Original DIY. How noisy is it? As is my habit, I wanted to answer this question scientifically.

So I bought a decibel meter:

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And I tested the Cannon, Original DIY, Blue Air 203/270E, and IQ Health Pro Plus on their highest settings from 1.95 meters away. That’s the distance between my pillow and where I put the purifiers. Here are the results:

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The cannon is noisier than I’d like, but it’s similar to the Blue Air on the high setting. To give you an idea of how loud that is, this decibel chart says that’s between “conversation at home” and “conversation in restaurant.”

It’s louder than I’d like, but fortunately I’ve found that the Cannon is still very effective on the lower settings:

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So I recommend running the cannon on a lower setting if you find it noisy.

Conclusions: 

  1. Cannon-owners can use the lower settings without sacrificing much performance.
  2. For people who are particularly sensitive to noise, the Original may be a better choice.
  3. For people who are VERY sensitive to noise, the Philips AC4072 is expensive (2,700 RMB), but it’s quite quiet on the low setting.

As always, I’m posting the data and methods below for fellow nerds.

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DIY Filter Compared to Expensive Filters

UPDATE: I now have directly comparable data with the DIY Filter, Blue Air, and Philips: Direct comparison tests.

In earlier posts (1, 2), I showed that you can make effective an DIY filter to clean air pollution out of your home. But just because it is effective doesn’t mean it’s as effective as the Ferrari filters. How effective is the DIY filter compared to the expensive filters?

I’ll attempt to answer this question from several angles in different posts.

 

Comparison with Dr. Saint Cyr’s Test

Here’s one method: comparisons with the published data from the blog of the Beijing doctor Dr. Saint Cyr (which was an original inspiration for me that air purifiers could actually reduce air pollution). He ran tests of an 11,000 RMB IQ Air and a 6,000 RMB Blue Air. I used the same calculation of effectiveness and compared his results for the pricey machines with tests of my DIY filter. Here are the results:

DIY Filter comparison

To make the comparisons more precise, I compared my filter results only to the tests he reports from the IQ Air and Blue Air on max power in his smaller room.

Dr. Saint Cyr calculated reductions based on outside air quality, which I do not think is the best method. I think it makes more sense to calculate reductions based on the room air before and after using the filter because my room air is significantly cleaner than outside air, even before using the filter. But to make the data comparable, I calculated effectiveness using Dr. Saint Cyr’s method.

Now, the comparisons aren’t perfect. Dr. Saint Cyr’s smaller room is still 6.5 meters larger than mine. He also doesn’t say how long he ran his filters and whether the doors were closed. My tests were with the doors closed and overnight, so the filter had several hours to run.

(Update: via email Dr. Saint Cyr said his tests were with doors closed and testing times of 1 hour+.)

But even if the difference in room size bumps mine down 5% and the others up 5%, that would mean 11,000 RMB and 166 RMB get you similar results. To illustrate that, I calculated a graph of how much you’re paying for each percentage reduction in air pollution:

DIY filter cost per reduction

Of course, the ideal test would use all three filters in the same room with the same particle counter. To that end, I will hopefully get the chance to borrow a friend’s Panasonic filter and test it in my home. I’ll post those results when I get them.

 

Conclusion: A DIY Filter can be as effective

Although the comparisons are imperfect, they show that a DIY filter is at least roughly comparable to expensive filters at a far lower cost. This illustrates my larger point: all you really need to combat particulate air pollution is a HEPA filter. In fact, Dr. Saint Cyr found the same thing in his tests of a much simpler Hunter brand HEPA filter. In a room with the doors closed, his HEPA got 91% of the pollution–similar to what I found.

For data nerds like me, I’m posting more details on my data and methods here:

Test Details:

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