A few months after I published my DIY tests, there were already Taobao stores up and running, selling DIYs even cheaper than my 200 RMB. I was intrigued. If we could really lower the cost of clean air, that’s a win! But we have to be sure these cheaper machines are as effective. So I […]
Tag: HEPA filter
Is a 30 RMB HEPA Reliable?
After I published directions for how to make your own purifier, people asked me: “Which HEPAs should I use? Is this one trustworthy?” That’s the type of question that makes a nerd like me happy because it means we need to get more data. So I ordered HEPAs from every manufacturer I could find, and I […]
HEPA Longevity Test: Day 200
One of the biggest questions when I started doing the DIY was how long the HEPAs last. Rather than just give people a nice-sounding answer, I wanted to see what the data says, so Gus has been dutifully turning on his Original DIY every day in his 12.3m2 Beijing bedroom and tracking how effective it is […]
Types of Filters
Premise: This blog is for people concerned about air pollution. There are many valid reasons people want air purifiers: pet allergies, pollen, and asthma. However, these are not what I’m concerned about while living in China. Here I assess purifiers solely based on whether they can help protect me from particulate air pollution. With that […]
Are All DIYs the Same? Poor Results from 还我蓝天
When I did my first experiments, several people told me not to publish the data. “Don’t give it away for free,” they told me. “Use it to make money!” I decided then that my main goal wasn’t to make money. I almost got tricked into paying $1,000 for clean air, and I wanted to help […]
How long do Smart Air HEPAs last? At least 90 days
The most frequent question people ask me these days is: how long does the HEPA last? This question is important because replacement HEPAs are the biggest long-term cost of clean air. IQ Air charges $370 for its filters. So if you have to replace the HEPA every two weeks, the DIY might not save you money in […]
DIY HEPA Filter over Time
Does the DIY air purifier work? Test results (1, 2) give a conclusive answer, but this series of pictures gives a visceral answer. I took a picture of the HEPA about every seven days for four weeks. Glad that black gunk’s not stuck in my lungs instead. In static form, here’s Week 0 and Week […]