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’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
“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 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
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
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:
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:
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:
So I recommend running the cannon on a lower setting if you find it noisy.
Cannon-owners can use the lower settings without sacrificing much performance.
For people who are particularly sensitive to noise, the Original may be a better choice.
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.
laundrylist 提问: What is the energy usage associated with running a cheap box fan for eight hours at night versus the two expensive models that you compared your cheaper model to? Excellent question! I’ve wondered about that myself. The fan is 50 Watts, compared to 27-215 for an IQ Air … Read more
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:
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:
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:
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