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. 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 still 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.


  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 AC4072is 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 (depending on fan speed). So they are comparable, although the IQ Air is using less energy on the lowest setting.

DIY Compared to Expensive Filters


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

In earlier posts (1, 2), I showed that you can make an effective DIY air purifier to clean Chinese air pollution out of your home air. But just because the DIY filter 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. 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 purifier. 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 (more on that later). 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: 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: