Where should an air filter be placed relative to the fan for best efficiency?

If you’ve been wondering whether the filter should go on the front or back of the fan, then you’re in luck, because this nerd right here has been building and testing DIY air purifiers to survive Beijing for the last four years! I’ve got actual data on this question, and the answer is the opposite of what most people tell me […]

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35 healthy Shanghai college students used a purifier for 48 hours. Here’s what happened to their bodies

There are two things we know about purifiers and one really important thing we don’t know.   1. We know that purifiers reduce PM2.5   Loads of tests have found this in labs and in real-world homes. I’ve tested the hell out of this, in my room, in bigger rooms, for 200 days of Beijing air, comparison tests against the […]

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