How to Make a DIY Air Purifier

How can we make a homemade DIY air purifier? Air purifiers can be extremely expensive, but they don’t need to be. After researching how different air filters work, I concluded that a HEPA filter is all that’s needed to make an effective air purifier that can capture viruses, wildfire smoke, dust, pollen and more.

Given that most air purifiers sell for thousands of dollars, I thought I’d try making my own homemade DIY air purifier.

WATCH: How to Make Your Own Homemade Air Purifier

3 Steps to Build Your Own Air Purifier

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Hold Up: Do DIY Air Purifiers Actually Work?

I’ve tested this DIY air purifier for over 1000 hours! The data shows they work! They are effective for the dangerous tiny PM2.5 particles including what you find in wildfire smoke and even tiny viruses! What’s more, they even outperform many of the big brands. With that out of the way, in this post, I’ll explain exactly how to make your own homemade DIY air purifier.

DIY Purifier Test AQI PM2.5

How to Make a DIY Purifier

#1 Buy a fan

It’s important to buy a fan with a flat front or back so that the HEPA filter you buy fits flush.

Fans with flat fronts usually have a recessed motor unit, so look for that. Here’s the one I bought below. Box fans also work great.

diy air purifier fan

#2 Buy a HEPA filter

For my very first homemade air filter, I first bought this one for ~US$16:

HEPA filter for homemade DIY air purifier

Since then, I tested HEPAs from all the manufacturers I could find to see if I could make an even more effective DIY air filter, and found one that captures more particles and has better airflow. Because I buy it in bulk and ship it through the shop for my social enterprise, it costs less than the first HEPA I bought. I’ve tested this HEPA filter with my particle counter, so I know it works (watch the live DIY filter test here).

#3 Prepare your fan for the HEPA filter

If your fan isn’t 100% flat – this is where the DIY filter fun starts! The fan I used wasn’t entirely flat, but by removing the front grill using a set of pliers, I was able to create a flat surface.

Step 3 in making a DIY air purifier

#4 Strap on the HEPA filter

Use string to strap the HEPA filter onto the front of the fan, and you’re done! Your very own DIY homemade air purifier.

If you have a metal bar in the middle sticking through the filter, don’t worry! You could saw the metal bar off, but my tests show it doesn’t seem to make a difference. Or better yet, make yourself a fancier DIY air purifier by finding a fan without a metal bar in the front.

Rear view of DIY fan air purifier
front view of HEPA attached to make DIY air purifier

To really improve your homemade fan’s performance, you could try taping your HEPA filter to the fan to avoid any leaks around the edges. Here’s a Corsi Rosenthal Box Fan where the fan is taped to the filters (multiple ones!) using masking tape.

#5 Admire your new DIY air purifier

Total cost for this DIY air filter: 166 RMB (US$27). Compare that to 8,000 RMB ($1,300) for the fancy purifiers here in Beijing. 

DIY 1.1 Air Purifier Filter HEPA

Want to Make a Strong DIY Air Purifier?

Since we shared this cost-effective DIY air purifier with the world, the Corsi-Rosenthal DIY air purifier has also appeared. This DIY air purifier uses multiple furnace filters (MERV 13 and above) with a large box fan. This type of design has a more powerful CADR, can be assembled in just 15 minutes, and costs around 100 USD.

Learn more: 4 things to know about the Corsi-Rosenthal (CR-Box) Fan »

Bottom Line: How to Make a DIY Air Purifier

#1 Buy a fan

#2 Buy a HEPA filter

#3 Pull the grating off the front of the fan

#4 Strap on the HEPA

#5 Admire your new DIY air purifier

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Your next question is probably, does this DIY air filter work? See a live test here. Here are a few other important questions:

  1. Filters: What combination of filters do I need to protect against everything?
  2. Stronger fan: Tests with the DIY Cannon
  3. How can I test it: Comparison tests of common air quality monitors

P.S. Should the filter go on the back??

You might be wondering, “shouldn’t the HEPA go on the back of the fan?” I always thought the answer would be “it works just as well both ways.” But I put it to the test, and the results surprised me.

A Simpler Way to Breathe Clean Air 

Smart Air’s founder and University of Chicago professor, Thomas Talhelm, created the first DIY air purifier 10 years ago that shook up the air purifier industry. Thomas then created Smart Air, a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air.

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We at Smart Air not only educate but also design and manufacture empirically backed, no-nonsense purifiers for homes and businesses, that use the same HEPA filters for a fraction of the cost of big companies.

Shop Smart Air’s Lineup of Cost-effective, Data-backed Air Purifiers

Smart Air’s award-winning Sqair bedroom air purifier

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Smart Air is a social enterprise and certified B-Corp that offers simple, no-nonsense air purifiers and provides free education to protect people from the harms of air pollution. We are proud to be the only certified B-Corp dedicated to fighting air pollution.

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