Whether indoor air is just as polluted as outdoor air is an important question for all of the millions of people living in heavily polluted cities. Yet I’ve heard a lot of disagreement about this question. I’ve heard people tell me it’s the same — “indoor air comes from outdoors anyway, so it’s the same.” […]
Category: Indoor Air

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 […]
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How do people in Beijing exercise with such bad air pollution?
I’m in Beijing right now, and I’m going to exercise today. So what can I do when the world outside my window looks like this? Would exercise do more harm than good? 1. The point where exercise becomes harmful Researchers at Cambridge analyzed studies on the benefits of exercise and the harms of air […]

Reducing Formaldehyde: 3 Things You Need to Know About Formaldehyde (Part 3)
Amid all the noise about chemicals in the home, these are three scientific, data-backed ways to reduce formaldehyde in the home. Once you’ve understood how to assess formaldehyde in your home and why testing machines are unreliable, here’s how you can act to reduce formaldehyde. Method 1: Open a window, since outdoor air has virtually […]

Would Living in a High Rise Protect Us From PM2.5?
Living on the 20th floor of a high rise building isolates people from the world. Cars, trucks, shaokao vendors—they’re all farther away. So does that mean PM2.5 is lower on the higher floors of buildings? The Test Tristan from the Smart Air team tested this by taking laser particle counters from floor 1 to […]

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: That led me on a long, unexpected journey. It turned out that I wasn’t the only one interested in breathing clean air in China, so I started a small social enterprise called Smart Air to ship these low-cost purifiers to fellow-air […]

Is the Molekule really better than air purifiers already on the market?
Over this last Christmas, I was at home on the couch, and my dad asked me if I’ve seen this new purifier he saw an ad for. He asked not because he’s interested in purifiers, not because I’m some PhD in fluid mechanics (I’m a cultural psychologist, not a physicist), but because I’ve […]

Off-gassing: 3 Things You Need to Know About Formaldehyde (Part Two)
An important question about formaldehyde is how long it takes for formaldehyde to off-gas in new homes and new furniture–how long will it take for levels to get back to normal? The best data I’ve seen suggests formaldehyde takes about two years to off-gas back to normal levels. Why We Need Real-World Tests When […]

Formaldehyde Detectors are Fake: 3 Things You Need to Know About Formaldehyde (Part 1)
Lots of companies will sell you formaldehyde detectors, but a simple home test will reveal they are fakes. Formaldehyde detectors routinely react to lots of common gases that are not formaldehyde, making the numbers basically impossible to interpret. Given that unfortunate fact, here’s what you can do to assess formaldehyde in your home. The […]