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 […]
Recent Filters Articles:
I recently published tests showing that carbon actually removes VOCs. But adding that carbon layer raises a question: adding carbon means the fan has to power through yet another layer of resistance. Does that make purifier less effective at removing particulates? Test Method To test this question, I ran 10 room tests with the Cannon and […]
Companies sell activated carbon filters to remove chemicals like formaldehyde and benzene, but does carbon really work? The Smart Air lab put real-world carbon filters to the test. Who Needs Carbon Filters Anyway? I wrote early on that my number one concern in China is particulate pollution. It’s on so many people’s minds that nowadays even […]
When I started Smart Air, a lot of people asked me how long the HEPAs last. Several people criticized the DIY on Zhihu because they said you’d probably have to change the HEPA so often that it’d end up being more expensive than the expensive brands. At the time, I really wanted to pull out […]
How long do Smart Air HEPAs last? My quest to give a solid empirical answer has now completed 130 days! Gus is still dutifully tracking the effectiveness of the HEPA he’s been using in his bedroom since January (with a trip to the US in the middle), calculating the percent reduction in particulates every night. […]
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 […]
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 […]
Matt Myers attended our workshop in September, and he used it straight through December. On December 7th, he sent me a picture of the blackest HEPA (and pre-filter) I’ve ever seen. Yikes! Time for a new filter! I’d be happy that black gunk is in the filter and not in my lungs.
joshuaw81 提问: Hi Thomas, just started one of your cannon kits earlier today and it’s already turning gray. Already a fan of your work! Two quick questions for you: 1- I received a foam/fiber square that is white on one side and light green on the other. I’m assuming this is packaging, and not part […]
My collaborator Gus Tate suggested we work with our HEPA manufacturer to get smaller, square HEPAs. Now we’re convinced the DIY filter just got a lot cuter: Cute and kicks PM 2.5 in the pants.