Air purifiers are devices that remove pollutants from the air and improve air quality. Air purifiers do this either mechanically, using air filters, or using ionizers or chemical reactions. Read more to learn about air purifiers, how to choose the best air purifier, and how they can protect against viruses, wildfire smoke, air pollution and PM2.5.
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.
Conclusions:
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.
I’ve wanted to know for a long time whether DIY air purifiers are as effective as the Ferrari filters.
In an earlier post, I compared my data to the tests of Dr. Saint Cyr (whose excellent posts inspired me to look into filters in the first place). But I noted that the comparisons were far from perfect because:
The rooms were different.
The Cyr post did not specify how long the tests were (and that can make a big difference if you’re looking at times under an hour–see this time comparison).
The Cyr post did not describe the particle counter or particle size.
How We Tested The Air Purifiers
But now I finally have directly comparable data! That’s because two kind souls donated a Blue Air 203/270E (3,600 RMB) and a Philips AC4072 (3, 000 RMB). That means I could finally test the DIY against expensive brands in the same room, for the same amount of time, with the same particle counter.
To do that, Anna ran 11 overnight tests with the Blue Air and 9 tests with the Philips. As always, I calculated effectiveness as percent reduction in particulates from the room air. Anna tested the air before she turned on the air filter, and then set a Dylos DC1700 laser particle counter to take hourly measurements of the air in her 15m2 room.
Anna used the highest setting on each purifier. (I’m putting the original data and more details about the methods for fellow nerds at the end of this post.)
And (drumroll!) here are the results:
The Cannon removed as much particulate as the expensive machines. Not bad for 450 RMB!
Yet all four filters were making the room air significantly cleaner. For particles 2.5 microns and above, all four removed over 90%. For particles 0.5 microns and bigger, all four removed over 80%. I’m not the first person to say: All you need to significantly reduce the particulate pollution in your home is a simple HEPA filter.
Based on the data, here’s how much you’re paying for each percentage reduction in 0.5 micron particles:
(And that’s not counting the cost of the exorbitantly priced replacement filters.)
Recently, a Chinese news article claimed air filter companies are making “falsely inflated profits.” That fits with this data showing that the Cannon removes as much particulate as the Blueair, yet costs about 10% per percentage of 0.5 micron reduction. Similarly, the Original DIY removes 4% less 2.5 micron particulate and 6% less 0.5 micron particulate than the Blueair on average, yet the Blue Air costs more than 16 times as much.
Bottom Line: Air Purifier Test
You can remove particulate pollution from the air in your home and pay far less than a Blueair or Philips
Ever since I started my DIY filter experiments, I’ve been wondering whether I could create a super DIY by using a stronger fan. In the past three months, my collaborator Anna has helped me test a half dozen different fans. She now has a home full of fans: …
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 …
Adam in Suzhou sent me a picture of a creative solution to a filter problem. The fan he had at his house had an opening that was slightly larger than the HEPA. So Adam cut out a piece of cardboard to close up the edges. Great idea! Adam …
Dr. Saint Cyr recently pointed me to great tests of air purifiers from the Shanghai Consumer Protection Bureau: The reason this type of research is so badly needed is that Western research (like this report from Consumer Reports) focuses on allergens, not general industrial air pollution. Allergens are probably more …
Independent Confirmation. I’ve always suspected that what I’ve “discovered” is so basic that people must’ve known about this before. Lo and behold, doctors at the University of Michigan recommend that people who suffer from allergies make a purifier for $25 with a furnace filter and a box fan. Getting independent …
How do I know if a DIY purifier works? I think you can break this down into two questions： Is the air coming out of the DIY purifier clean? The test results are as clear as can be. The DIY purifier shoots out very clean air. But is that enough to actually …
DIY Filter TestWatch this video on YouTubeSubscribe to Smart Air on YouTube I made a video to show if the air coming out of the HEPA filter of my DIY is clean. See the filter in action. This settles that the air is coming out clean. But is that enough …
Smart Air is a social enterprise and certified B Corp that offers simple, no-nonsense air purifiers and provides free education to protect people from the harms of air pollution. We are proud to be the only certified B Corp dedicated to fighting air pollution.
