Based on my research into how different filters work, I concluded that a HEPA filter is all you really need to fight particulate air pollution in China. Given the fact fancy air purifiers run for 8,000 RMB here in Beijing, and I’m only here for a year, I thought I’d try making my own. I’ll give details on how well it works later, but here I’ll explain how I made it:
1. Buy a fan. It’s important that it has a flat front so that you can strap the HEPA filter to it. Fans with flat fronts usually have a recessed motor unit, so look for that. Here’s the one I bought for 58 RMB:
3. Pull the grating off the front of the fan. It helps if you have pliers for this. Then turn the power setting to 3 and pull the knob off. The knob gets in the way of the HEPA. Without the knob, I turn the fan on and off by plugging and unplugging it.
4. Use string to strap the HEPA filter onto the front of the fan, and you’re done! The metal bar in the middle will stick through the filter a little bit. You could saw the metal bar off, but my tests show it doesn’t seem to make a difference.
Total cost, 166 RMB (US$27). Compare that to 8,000 RMB ($1,300) for the fancy purifiers here in Beijing.Your next question is probably, does it work? See a live test here.