A decade ago, Beijing’s air quality was much worse, and the easiest way to breathe clean air was to buy an air purifier. But if you turned to Taobao, one of China’s leading online shopping platforms, the cheapest air purifier would still set you back about 10,000 yuan ($1,371), a sum most people would consider too high a price to pay.
Thomas Talhelm, an American expat based in Beijing, wanted an affordable solution. He researched air purifiers and found that the “active ingredient” in most of them was a “high-efficiency particulate air” (HEPA) filter, a type of pleated mechanical filtration device also used to trap dust in vacuum cleaners. Then there’s a fan to move the air through the filter.
Talhelm found a HEPA manufacturer, ordered a
