Beijing’s DIY Clean Air Movement: If You Can’t Buy an Expensive Air Filter, Build One

On days when Beijing’s heavy air pollution is especially pungent, you can smell and taste the acridity—whether you’re outside on the street or inside most buildings. Air pollution doesn’t stay outdoors but seeps inside through open doors and window sealings. On most days, levels of dangerous pollutants, such as PM 2.5, are somewhat lower outside than inside, but not much lower.

This unhappy fact has fueled a growing market for pricey indoor air filters in China, made by such companies as Chicago’s BlueAir and Switzerland’s IQAir. A basic model will set you back at least $800. And ideally, you should have one for each room in your home, school, restaurant, or office. In other words, these filters don’t come cheap.

But what if there’s a simple but less costly way to achieve roughly the same effect? Now there might be.

During the Beijing “Airpocalypse” of January 2013, Thomas Talhelm, a Fulbright scholar spending a year in China, began to research how air filters worked. Soon Talhelm realized that the essential components—a HEPA filter, a fan, and a velcro strap to hold them together—could be purchased on Taobao, China’s leading e-commerce site, for less than $35. So he rigged up his own air filter and invested in a scientific particle monitor to see how well it worked. (The DC1100 Pro Air Quality Monitor, which measures levels of PM 0.5 and PM 2.5, was more of a splurge, at $260.)

Using a HEPA filter strapped to a simple flat-surfaced fan, he found that the device reduced indoor levels of PM 0.5 by 84 percent and indoor levels of PM 2.5 by 92 percent. When he tested a more powerful rotating fan, the results were even better. His DIY device lowered indoor levels of PM 0.5 by 97 percent, and indoor levels of PM 2.5 by 96 percent. (The expensive premade air purifiers he tested had similar results.)

Last fall, Talhelm began giving DIY workshops on how to build his simple air filters—at first to close friends, then to other interested expats, then to a wider audience of foreign and Chinese folks worried about their lungs. Last November he and a couple of friends set up a Taobao store to sell their DIY air filter kits—priced at 200 renminbi (about $33). Orders poured in from Beijing, Shanghai, and other Chinese cities. (They’ve even received order requests from India but haven’t worked out foreign shipping details yet.) The team hired three people to help fulfill orders—packing fans, filters, and straps into boxes and arranging courier deliveries.

Talhelm is now back in the U.S. finishing his Ph.D., but Gus Tate, his friend and business partner, is still in Beijing overseeing the growth of their enterprise, called Smart Air Filters. Tate hesitates when asked whether he should be identified as the chief financial officer, the chief technology officer, or general manager. “I’m just the guy who’s doing this who’s not Tom,” he tells me. Tate invited me to meet at Beiluo Bread Bar (motto: “Mean Beans and Badass Bread”), which was his mobile office this afternoon in Beijing’s trendy Gulou neighborhood.

While Smart Air Filters is somewhere between a labor of love and a business, it’s clear that demand is high for affordable air filters in China. Tate says they now receive 70 orders a day, on average—and that number spiked to more than 100 orders a day during Shanghai’s own Airpocalypse last December.

I first heard of DIY air filters last fall through an e-mail listserv for a group of mostly expat energy professionals, the Beijing Energy & Environment Network. About a week ago, my friend Li Hui, a 20-something handbag marketing director in Beijing, also sent me a Weixin message enthusing about the DIY workshop she’d just been to (“It is very interesting … because of the air pollution and the crazy [expensive] air filter market out there”). Next Saturday, May 17, is another DIY air-filter workshop at Beijing Normal University, and this time I’ll go, too.

Meantime, as Gus Tate openly acknowledges, other entrepreneurs in China are now seizing the idea and running with it. Together we searched for “DIY air filter” on Taobao and came up with more than a dozen hits, in addition to their own site. Most used similar fans and HEPA filters.

Does the copycat phenomenon bother you—from a business perspective? I asked. Or is it just a good thing that more people may breathe cleaner air?

“Well, it’s mostly good,” Tate began. “But wait, hey, that’s our picture.” We clicked through to one site displaying photographers and translated text lifted directly from Smart Air Filter’s website (and only vaguely crediting “foreigners in Beijing”). “I kind of wish they wouldn’t use our pictures,” he said. Tate had mixed feelings about the sincerest form of flattery. But undoubtably, there’s a strong market for cheaper, cleaner air in China.