A Yankee Inventor Takes On Beijing Smog

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.)

Read more at Bloomberg Businessweek.