In 2013, I made a DIY purifier to get through an apocalyptic Beijing winter. The DIY wasn’t pretty, but it worked. Hundreds of days of tests showed it cut tiny 0.5 micron particles in my bedroom by an average of 84% (1, 2, 3). The DIY proved that air purifiers don’t have to […]
Tag: air purifier
Can HEPA filters capture nanoparticles?
Many big purifier companies claim only their HEPA filters capture nanoparticles, like this Molekule ad. Although this claim is false, even journalists repeat this myth. Why is this belief so pervasive? One reasonable explanation is that the definition of “HEPA” leads people down that route. For example, this definition on Wikipedia […]
What combination of air filters do I need to protect against everything?
This will sound like a grand claim, but two filters are all you need. Here’s why (with data). Very Reasonable Reasons To Be Skeptical Why might you be skeptical? For one, big purifier companies are in an arms race to tell you they have more filters than the next guy. Simpleton Thomas here is […]
How to Get the Most Out of Your Purifier
If buying an air purifier is the first step to breathing clean air, the second step is knowing how to use it best! Here are the 4 most important things to know about how to use an air purifier—based on data, not intuition. 1. Note down the date of purchase HEPA filters have a […]
What’s the HEPA lifespan of the Blast and Blast Mini?
Ever since we launched the Blast and Blast Mini in 2017, we’ve wanted to get good data on how long hepa filters last. These filters are huge, 10-20 times the size of our DIY purifier filters in fact. We’d expect the HEPA lifespan to be much longer, but let’s see what the data says. The Problem with […]
This One Region in China Saw a Pollution Miracle in 2018
New analysis from Smart Air shows that China is making progress on its “war on air pollution.” PM2.5 air pollution was down in 14 out of China’s 15 largest cities. Yet one region saw far more progress than the rest. South Sees Modest Air Quality Gains In southern China, from Shanghai to Shenzhen, […]
China’s 15 Biggest Cities Saw Better Air in 2018 — Except This One
A new analysis of air quality from 15 of China’s largest cities shows that PM2.5 fell in all cities—except one. From Shenzhen to Xi’an, air pollution was down in 2018. Yet Zhengzhou, capital of Henan province, actually saw pollution rise 7%. With this increase, Zhengzhou now averages over 6 times the World Health […]
Top Air Purifiers in Shanghai Consumer Protection Bureau Tests
Using actual air purifier test data on is the best way to cut through the misleading marketing claims purifier companies make to try to get us to pay more money for clean air. For that reason, I’m always on the look out for good test data. Data is power. One source I like […]
What is the best air purifier on the market today?
I started thinking about this question a lot because I was living in Beijing, and the “airpocalypse” struck: I had a cough I couldn’t shake for weeks, so I started doing research into air purifiers. Unlike another answer here, I wasn’t concerned about allergens like pollen. I was concerned about the very small particles […]
Should air purifiers have the filter on the front or back?
When I made my first DIY purifier, I put the filter on the front: Within a few weeks, several people told me I was an idiot. Why’d you put the filter on the front? That led me on a long, unexpected journey. It turned out that I wasn’t the only one interested in breathing […]