How to Make a DIY Air Purifier

I’m on a quest to make a DIY air purifier. Step one was my research into how different filters work. Based on that, I concluded that a HEPA filter is all you really need to make an effective air purifier and fight particulate air pollution somewhere like China or India. Given the fact fancy air purifiers run for 8,000 RMB in Beijing, or 100,000 INR in Delhi and most people don’t have that kind of money, I thought I’d try making my own DIY air purifier.

Wait, Does the DIY Purifier Actually Work?

I’ve tested the heck out of this DIY air purifier! The data shows it works, even for tiny PM2.5 particles, compared to the big brands, with a control test room, over 200 days, and in a completely controlled test environment). But here I’ll explain how I made it.

 

DIY Purifier Test AQI PM2.5

 

How to Make a DIY Purifier

#1 Buy a fan

It’s important that it has a flat front or back so that you can strap the HEPA filter to it.

Fans with flat fronts usually have a recessed motor unit, so look for that. Here’s the one I bought for 58 RMB (about US$8.50):

diy air purifier fan

 

#2 Buy a HEPA filter

For my very first homemade air filter, I first bought this one for 108 RMB (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 air flow. Because I buy it in bulk and ship it through the shop for my social enterprise, it costs less (75 RMB) than that first HEPA I bought. I’ve tested this HEPA filter with my particle counter, so I know it works (watch live DIY filter test here).

 

#3 Pull the grating off the front of the fan

This is where the DIY fun starts! It helps if you have pliers for this. Then turn the power setting to 3 and pull the knob off – we’ll be using this DIY air purifier on the highest setting.

The knob gets in the way of the HEPA. Without the knob, I turn my DIY air purifier on and off by plugging and unplugging it.

 

Step 3 in making a DIY air purifier

 

#4 Strap on the HEPA

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

The metal bar in the middle will stick through the filter a little bit. 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, like the DIY air purifier I ship through Smart Air.

 

Rear view of DIY fan air purifier

front view of HEPA attached to make DIY air purifier

#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. I now ship a simple fan and a filter with a simple upgrade that increases clean air output by 15% over my original design for 228RMB (US$37).

 

DIY 1.1 Air Purifier Filter HEPA

 

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.

 

The Sqair air purifier Kickstarter

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Muhammad Khizar

Hi, this maybe a silly question. I just made a DIY air purifier similar to instructions here. How much of air flow should we be able to feel at the front of the HEPA filter ? Little or none at all as I am getting almost none.

Hey Muhammad! This is a very common question for DIY air purifiers. Even if you can’t feel a lot of air coming out of your DIY, it doesn’t mean it’s not working. With the original DIY that Tom made, it also felt like very little air was coming out, however tests proved it to be effective. Check out this video of Tom showing this: https://www.youtube.com/watch?v=JpfpZofUzNo&t=7s To ensure you’re getting the maximum air possible out of the purifier, make sure there’s a good seal between the fan and the filter, and that no air is leaking out of the back of… Read more »

davis.c.fay

Hello! I had a similar problem to Muhammad’s – little to no air flow out of the front of the filter and significant flow out of the back of the fan (even after taping up all of the side vents in this particular desk fan.

What do you recommend to correct for this? I’m in the USA, so I don’t believe I have affordable access to the same fan listed in the instructions in this blog post.

If you’re in the USA, then you’re in luck! I suggest you get yourself a box fan and a large furnace filter. These fans are extremely powerful and very affordable in the US. They should be a great option for you!

Vivi

Hi Thomas,I want to buy your HEPA Filter through Taobao website. However i have a big question : the last product is an air purifier machine or a fan having air purifier function. Is this product still a fan? Does it make cool anymore?

Hey Vivi, Tom’s out doing nerdy stuff so I’ll reply on his behalf! With the HEPA filter attached, the airflow is much less than a regular fan, so these DIY purifiers don’t have a strong cooling effect. However since the HEPA filter is detachable from your fan, you should be able to remove the HEPA filter at any time to turn the DIY air purifier back into a fan.

Vivi

Thank for your reply. Finally the fan is not a fan anymore, right? The fan becomes an air purifier?

Mona

Hi, I wanted to back/order the Squair on Kickstarter but am I one day too late? The photo says it ends on July 5th, which is today, but I can’t seem to find a link to order… thanks!

Hey Mona, you just missed the Kickstarter, unfortunately! The campaign ended midday on the 5th July! If you want to be the first to know about pre-orders, sign up to our exclusive mailing list here

Shravan

Finally the fan+filter is to be fitted as a fan (pumping air towards you) or as an exhaust fan (pumping air outside) ?

dguevara

Is possible to have those ones in México City ?

Hi Daneil! We can ship to México City, but shipping costs can be pretty steep. What we suggest is you pick up a HEPA filter from our store, and source a local fan in México City, to save on shipping! More info: https://smartairfilters.com/cn/en/shop/worldwide-orders/

dguevara

thanks a lot, I will do it. we are also interested in becoming a tester and create data for México and all LatAm countries. we are an IOT network that wants to help solving air quality problems in our regions. this is our website wndgroup.io , let us know how we can collaborate.