Four years ago, I was coughing through a Beijing winter and wanted some clean air. But all the purifiers I could find cost hundreds of dollars, so I strapped a filter to a fan I had at home and made my first DIY purifier.
It wasn’t pretty, but I tested it with a laser particle counter, and the data showed it significantly reduced the particles in my bedroom air.
It worked, but it had some problems:
- It’s loud. On high, it’s about as loud as major purifiers, but that’s still loud.
- It’s kind of a hassle. You have to strap the filter on, and I’ve seen some people do it wrong.
- The fan isn’t really made to power through a dense HEPA filter. A stronger fan would give a lot more clean air.
Fast forward 4 years and hundreds of tests later, I’ve got a new pair of machines that squashes those problems, and they’re badass. They’re my first non-DIY purifiers. Meet the Blast and the Blast Mini (or Ladakh and Ladakh Mini in India!).
OK, OK, the Blasts are pretty basic. It’s a metal box with a fan and a super fat HEPA filter inside. That’s not some kind of technological marvel. All purifiers are boxes with a fan and a filter inside, but the Blasts have a bigger fan and a much bigger HEPA. That means:
The Blast Mini puts out as much clean air as about 2.2 Blueair’s or IQAir’s.
But with that much air coming out, it’s gotta be noisy, right? This bad boy is actually quieter than a Blueair or IQ Air.
As always, I’ve been testing this under real apartments and publishing all the data and methods. But it’s kind of unfair because they clean so fast. Here’s the Blast in the 34 m2 Smart Air office, and here’s a video of the test.
Throughout all this testing, several times I’ve asked, “Did anyone turn this on?” It’s that quiet. After experiencing it for a month, I bought up the first few to give to a few friends.
Your lie detector should be going off by now. How can it be more powerful and quieter? Well, for one, the HEPA is fat.
(area calculated taking the HEPA filter and opening all the folds)
That means the air can spread out over a large area. Imagine trying to blow really hard through a straw. Now imagine blowing air through a traffic cone. It’s a lot easier, and it’s quieter.
Second, this guy here Paddy engineered the fan and air duct, and he’s an aeronautical engineer. Really. He believes in his creation so much he even pretended to read a magazine next to it.
It also means he knows how air moves and designed the fans so that they work well and stay quiet.
So the Blasts are more powerful and quieter, well then they must be more expensive. Nope:
I calculated that the Blast Mini can easily clean up to 85 m2. That’s good for most apartments or houses. And for big apartments or places like offices, gyms, and cafes, there’s the Blast which cleans up to 130m2. And because the Blast’s HEPA is twice the size of the Blast Mini’s, it’s even quieter.
So, what makes the Blasts so special then? Not a whole lot, just in true Smart Air fashion I’ve packaged them without the high price tag and margin, and bundled them along with hundreds of hours of test data to verify they actually work.
My aim is still the same: make clean air more affordable, and get it out to more people.
As I write this, I want to apologize for feeling like I’m selling this thing. After four years of working on Smart Air, I still haven’t taken a penny for myself. I’ve got a day job (I’ve now moved from grad school life to professor life), so I use any leftovers to pay the Smart Air team an almost-livable wage, set up in India and Mongolia, and subsidize our educational workshops.
So I’m sounding a bit different from usual, but it’s because I’m excited. Four years after building my first DIY, the accumulated data is saying my initial hunch was right—it IS possible to get clean air for a heck of a lot less than what Blue Air and IQ Air say. Data sets us free!
P.S. I couldn’t help making a GIF.

Paddy graduated in aeronautical engineering from Bristol University, and now runs Smart Air’s operations from Beijing. He’s an advocate for open data, free information and transparent business.
WOuld really love to see this on amazon or some sort of affiliate program so I can promote it
Thanks John, sounds like a great idea! We already have the Blasts on Amazon India (they’re called the Ladakh and Ladakh Mini there). Which country are you based in and where would you like to see the Blasts for sale?
I am based in South Africa and my audience is mostly American and European, and I do get some Indian visitors as well. I will see how I can work with your Indian amazon links for now but Amazon links for the U.S and E.U will be awesome. Thanks for reaching out
I think comparing the product to Blue Air is not relevant anymore as companies such as Xiaomi and Mijia makes it more affordable now, and have a pretty accurate automatic mode which is more friendly than these pick up devices for industrial use (and which i would not guarantee how safe their components are are they must be for domestic market)
You’re right Flax! Many new purifiers have come on the market in the past few years which as you say have a much lower price. The Xiaomi purifiers are a good example of lower cost purifiers on the market! Although one of biggest downsides of the Xiaomi – which we spent a long time fine tuning for the Blasts – is the noise level. The Xiaomi gives a CADR of 310cbm/hr, but at a whopping 69dB. That’s pretty unbearable for most people. The Blast Mini on its lowest setting gives a CADR of 340cbm/hr, at a noise level of just… Read more »
Hi. For years I’ve been using 3M Filtrete cut out sheets on my air conditioners and on the backs of electric fans. Saw a Blueair 205 on sale recently, got interested, and decided to research more on air purifiers. Came upon your site. Great products! However there are some important errors you made in the comparison calculations. It appears that you compared the Blast Mini and Blast CADR using **cubic-meters-per-hour** (585 and 890 m³/hr) to the Blueair 203 and IQ Air Health Pro 250 using **cubic-feet-per-minute** (155 and 259 cfm respectively, according to their websites). So instead of the Blast… Read more »
Hi Sam, great insights! You’ve sure done some good digging work! The CADR values we got for the Blue Air came from the AHAM official website, double checking it again, it seems there’s a bug with their website whereby if you change the ‘units’ to ‘metric’ it still outputs the CADR of the BlueAir 203 as ‘155’. Having checked the BlueAir official website, you’re right: the CADR is 155cfm or 263cbm/hr! IQAir value is a little bit more difficult to decipher. IQAir doesn’t seem to give any CADR values (either in cfm or cbm/hr) for their machines, so in order… Read more »
Paddy,
Thanks for the reply! Your explanation for the area standards was very clear. Made it easier to compare purifiers and realized to really just depend on a combination of CADR, price, power and sound level.
I found the IQAir specs on the linked pdf on their website at https://www.iqair.com/international/home-air-purifiers/healthproseries.
Hey, respect for your personal story, and obviously an awesome product development!
I’m smoking, that’s why I want to buy one of that air purifiers…
I also thought about an DIY project, and design my own, by this way I found your website…
Can you send me some price infos, and shipping in the EU, Vienna, Austria, please?
Wish you all the best, kind regards,
Sebastian
Can your purifiers be sent to Taiwan? Do they have 110v version?
Hi Jian-Hong! Paddy here in Beijing. The motors we’re using are currently 240V only, but if you’re looking to order a larger quantity of units (more than 20) we can make sure they include 110V motors that work in Taiwan. Get in touch with us at [email protected] if you do