#PollutionGram: Beijing

Ever since I started my DIY 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: 

After months of tests, one fan has proven itself to be the king of fans. I’m now ready to unveil a newer, more powerful DIY:

Informally I’ve been calling it the “大炮,” the cannon. That describes how it looks, but also what it does to air pollution. Simply put, this thing kicks butt: 

Even when you look at the really small stuff—PM .5—the cannon is equally impressive: 

Over five nights of testing, the cannon removed an average of 97% of PM .5 and 96% of PM 2.5. I think this may be close to the upper limit of how much particulate pollution you can remove from your air with a home-use filter.

But wait, isn’t the original DIY effective too? That leads to the question…

What’s the difference between the Original DIY and the Cannon?

1. In 8-hour tests, the cannon removes 4-13% more particulates. 

In the overnight tests, the cannon is removing somewhat more particulates—especially the smaller PM .5. 

Remember, this is an average, so the difference is larger on very polluted days and smaller on clean days. (You can see the data for individual days in the raw data at the end of this post.) 

2. The Cannon cleans faster.

Because the cannon circulates air a lot faster, it reaches those numbers faster than the original DIY.

This is harder to illustrate than average effectiveness, but you can see it clearly in our controlled tests. In the controlled tests, we burn a source of PM .5 pollution (a stick of incense) in a closed room. After 20 minutes, we turn on the filter. In those tests, the Cannon is clearly faster: 

3. The Cannon is better suited for very large rooms.

Some people have told me they want to use the original DIY to clean large spaces, like stores and multi-person offices, but the original DIY is not really made for large spaces. If you want to clean a large area, the Cannon has the power to get the job done. 

Is it still affordable?

One obvious question is, sure it works better, but won’t it be way more expensive? We’re still figuring out how much the cannon will cost to order and ship from Smart Air (it’s heavier than the original DIY), but I’m hoping we can set the price between 400-500 RMB. At that rate, you’d be removing 97% of your PM .5 at 3.6% the price of the 11,000 RMB IQ Air. 

When should I choose the Cannon vs. the Original DIY?

I would recommend the Cannon for:

1. People with larger spaces, like large offices or bigger-than-normal living rooms.

2. People who are very concerned about air pollution and therefore really value that extra speed and effectiveness—for example, people with health problems, pregnant women, and children.

But for most normal rooms, the original DIY will still do the trick.

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