Soon after I started making DIYs, people emailed me asking if we could make a DIY for their car. My initial reaction was, “Great idea!” On the highways, we’re surrounded by all of that awful pollution. Best to purify that air. But as a methodical nerd, I wanted to do some tests first. The results of […]
Category: Filters
Can I Clean or Wash HEPA filters? – Supplemental Data
This post contains supplemental data for the post “Can I Clean or Wash HEPA filters?“. It includes detailed information about the testing method, and the original data, open-sourced for all to view. Click here to view the original article Open Data Particle Capture Tests For the particle capture tests, CK used a Met One GT-531 […]
Can I Clean or Wash HEPA filters?
HEPA filters are a nearly perfect solution for air pollution. They are backed by tons of scientific tests; they’re pretty cheap; they use about as much energy as a lightbulb; they even have documented health benefits. Just about the only remaining problem is that you have to throw out the HEPA filters every few months. So wouldn’t it […]
Can Activated Carbon Remove Formaldehyde?
In a previous blog post, I wrote about how I tested activated carbon’s effectiveness at filtering out VOCs from cigarette smoke. I also wrote about who actually needs activated carbon (hint: not everyone). One type of VOC that many people are concerned about – especially in China – is “Formaldehyde”. It’s not because Chinese […]
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 […]
Does adding a carbon layer reduce particulate effectiveness?
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? Methods To test this question, I ran 10 room tests with the Cannon and 10 […]
Does Carbon Really Work?
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 the guy I buy chuan’r from knows the word “PM 2.5.” HEPAs do an amazing job at removing particulates, but particulates aren’t everything. Gases like volatile organic compounds (VOCs) are so small that they slip through HEPAs. “VOC” […]
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 […]
HEPA Longevity Test: 170 Days
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? Longevity Test Day 130
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. […]