“I can give you a real-world view from employers and employees,” says That’s not good for the real estate market, especially in big cities like New York.

What is a life hack that you think everybody should know?

A life hack I made in my bedroom accidentally made its way into the homes of 40,000 people in China and India. But I was really just trying to solve my own problem.

The problem was I was coughing. The air outside my window looked like this:

I was living through an “airpocalypse” in Beijing, and I finally understood why I had a cold every other week this winter.

I thought fixing the problem would be easy. I’d just buy an air purifier. But the one everyone was talking about cost $2,000!

Even the “cheap” one cost $500. I was a poor PhD student doing psychology research. I didn’t have thousands of dollars to outfit my apartment with purifiers.

But I thought I smelled bullshit. Does safe air really need to cost a thousand dollars?

Here’s where I’m tempted to say I did in-depth research, but then I’d be the bullshitter. In reality, all the information I needed was on this Wikipedia page.

  • HEPA filters capture over 99% of particles 0.3 microns and above (below too!)
  • These magical HEPA filters were invented in the 1940s.
  • They’re not patented, so anyone can make one.
  • And they’re cheap because they’re made out of synthetic fibers, like a shirt or a backpack.

Since I was in China, I found a factory that made HEPAs, ordered one for about $15, and strapped it to a fan I had at home.

It wasn’t pretty. I didn’t even have anything to strap the filter on, so I used a tape measure I found in the closet of the apartment I was renting.

OK, it has the main ingredients of a purifier, so it works in theory, but does it work in real life? I spent $30 to make the purifier, and then I went out and spent $300 on a laser particle counter. (It was the cheapest I could find.)

It was a dorky move, but I wanted to know for sure. After 5 weeks in my bedroom, I could see plenty of junk particles stuck in the filter.

But I wanted to know whether it was actually capturing the really small particles that can penetrate deep into our lungs. That $300 laser particle counter could tell me that.

Here’s what the DIY did to 0.5 micron particles in my bedroom over 8 hours:

I tested it over and over—hundreds of days, with a control room, with a stronger fan, against the big brand purifiers that I borrowed from my rich friends. Eventually, I saw enough data that I was convinced. This $30 DIY purifier was removing significant amounts of tiny particulate from my Beijing bedroom.

I wanted to tell the world that those $1,000 purifiers were ripoffs. I made all the data and testing methods open source. I wrote up the instructions for how to make one.

I thought a few fellow expat nerds might take notice. But it turns out a lot of other people were facing the same problem. One day, I saw The Atlantic wrote about my little purifier.

And Bloomberg.

And the BBC.

I was like…

I thought the hack was pretty simple, but soon I started getting emails from confused people. “I can’t find that type of fan! Can I use this fan?”

“That’s cool, but I’m too lazy to build one!”

So two friends and I started a website to ship DIY purifiers to people all over China. We called it Smart Air.

That was six years ago. Since then, we’ve shipped low-cost purifiers to over 40,000 people across China.

And because China isn’t the only place with an air pollution problem, we started Smart Air in India, Mongolia, and the Philippines. We’re also trying to raise money to launch the most cost-effective manufactured purifier in the world.

Meanwhile, I finished my PhD research, and I’m still a cultural psychologist in my day job. I’m NOT an expert in air pollution, just a stubborn nerd that faced a problem that turned out to be the same problem lots of other people were facing.

I never imagined my bedroom DIY project would find its way into thousands of people’s homes. I guess nerdery comes in useful sometimes.

Breathe safe!