Is the Molekule Air Purifier Worth It? Review

Over this last Christmas, I was at home on the couch, and my dad asked me if I’ve seen this new Molekule air purifier he saw an ad review for.

He asked  because I’ve been building and testing DIY air purifiers ever since a Beijing airpocalypse in 2013 had me coughing for weeks.

The lesson I’ve been learning throughout my testing is that big purifier companies actually love smoke. That smoke comes in the form of claims that we need filters imported from Switzerland (learn more about that ‘fancy’ Swiss company I’m talking about here), not because they’re high profit margin, but because the technology is better.


cost of air purifiers very expensive



That’s the backdrop that was in my mind as my dad handed me his iPad, and I clicked on the Molekule air purifier ad. So let me do a Molekule air purifier review and look at what they claim.


Molekule Air Purifier Claim #1

Immediately, I saw this claim.


Molekule air purifier review


These guys are so technologically advanced they haven’t read the Wikipedia page about HEPA filters. If they had, they would’ve learned that HEPA filters are actually fantastic at capturing particles under 0.3 microns.


HEPA filter filtration efficiency


See, the problem is our intuition is to think of HEPA filters like a net. If a particle is smaller than the holes in the net, it gets through. So the smaller the particle, the harder it is to capture. Makes sense.


Air filter net


That logic works for objects as big as marbles. But when we get to really small particles—like particles under 0.3 microns—things start getting weird. Particles that small have so little mass that they actually get bounced around like a pinball when they hit gas molecules (known as Brownian Motion). So they move in random zigzag patterns.


Brownian motion air filter


Why that matters is that tiny particles are small enough to fit through HEPA filters—if they flew straight. But because they fly in zigzag patterns, they end up hitting the fibers and getting stuck.

OK, that’s a lot of theoretical explanation. Is there any test evidence for this? There’s lots! One test I like is this thesis on duct filters (never thought I’d say that about a thesis on duct filters).

Air filter microns F6 F7 F8 MERV


That’s the percentage of particles the filters captured at different sizes. See how the effectiveness goes down, but then starts to go up again? That’s below 0.3 microns—the particles Molekule claims that regular purifiers can’t get.

By the way, this study was on furnace filters, which are lower grade than HEPA filters. But the principle works for any fiber filter. It works for the HEPA filters that are in purifiers (see this guy’s tests down to .01 microns) and even masks (I describe mask tests down to .007 microns here). That means you don’t even need a fancy HEPA filter for Brownian motion to work its magic.

So why is Molekule claiming HEPA filters can’t capture any particles below 0.3 microns?

Molekule air purifier review HEPA


Either they don’t know this basic fact about purifiers (in which case, I’m highly skeptical of their claims of being experts), or they’re straight up lying about purifiers to sell you a more expensive one (in which case, I don’t trust them).

Molekule Purifier Claim #1: Busted

The Molekule Air Purifier claim to superiority about particle sizes is false.

Smart Air

Molekule Air Purifier Claim #2

Their second big claim is about bacteria. They claim that bacteria will grow on regular HEPA filters and then get released back into the air, so you need their Molekule technology to kill that bacteria.

Molekule air purifier HEPA mold

I’ve used HEPA filters in my Chinese apartments for years. I’ve also shipped 40,000 of these low-cost DIY purifiers to people all over China and India through my social enterprise Smart Air.

Smart Air


That includes lots of people in hot and humid Shanghai and Shenzhen, not to mention basically all of India (which qualifies as hot and mostly humid). I’ve never once seen or heard of mold or bacteria growing on these HEPA filters. That’s despite the fact that I had a mold problem in my Beijing apartment before I started using purifiers.

Molekule Purifier Claim #2: Busted

Is it theoretically possible for bacteria to grow on a HEPA? I suppose so. But even in these extreme environments, I’ve seen absolutely zero evidence that it actually happens. If it were a problem, I don’t see why airplanes and hospitals use HEPA filters to trap bacteria

Smart Air

Molekule Air Purifier Claim #3

Molekule says HEPA filters can’t capture viruses because they’re too small. But the Molekule air purifier can!

Molekule air purifier review


This gets back to point #1. HEPA filters (and really most filters) are great at capturing viruses.


HEPA filter air purifier viruses


Viruses are solidly in the range of very, very high efficiency for HEPA filters and even masks.


Air purifier viruses particle size


Molekule Purifier Claim #3: Busted

 HEPA filters (and really most filters) are great at capturing viruses.

Smart Air

Molekule Air Purifier Claim #4

About allergens, Molekule says HEPA filters “only traps larger allergens” and then releases them back into the air anyway.


Molekule air purifier review allergens


We’ve seen the claim about small particles before, so we know that’s wrong. But what about releasing them back into the air?

I’ve seen people worry about this, but I’ve never seen any evidence for it. And in the tests I’ve done, all I find is evidence of the opposite. Let’s take this 200-day test longevity test. See, I wanted to know how long a HEPA filter would last on my DIY in real Beijing air. So my Smart Air co-founder Gus tested it everyday in his Beijing bedroom for 200 days.

Here’s what a regular test day looked like. There’s particulate in Gus’s bedroom (red line) and outside (blue line).


DIY filter PM2.5 test


Here are 10-day averages all the way out to 200 days (all original data available here).


DIY Filter longevity test HEPA


Even out to day 200, the HEPA filter was managing 50% reductions in room particulate. At no point was the HEPA filter making room air worse.

That’s just not how filters work. They capture particles. They don’t release them. Unless you’re shaking them or cutting them open, they’re not going to release those particles back into the air.

Molekule Purifier Claim #4: Busted

That’s just not how filters work. They capture particles. They don’t release them.

Smart Air

Molekule Air Purifier Claim #5

There is one claim that strikes me as “could be true.” It’s their claim that the machine “destroys” chemical gases known as volatile organic compounds (VOCs). That includes stuff like formaldehyde and toluene, which come out of products that we buy, like carpeting.


Molekule air purifier review VOCs


They’re right that HEPA filters don’t capture gas pollutants. HEPAs are for particles, not gases. They’re weirdly claiming that carbon is only effective for 80 minutes. That must be an incredibly tiny carbon filter. It doesn’t match my tests with the carbon filters on regular purifiers.

But does their machine actually “destroy” VOCs? Maybe it does! If so, that would be the only actual selling point of this machine. Unfortunately, they don’t explain what the filter is (beyond using fancy-sound terms like “nano”), and they don’t provide any data with enough detail that I could assess it.

Molekule Purifier Claim #5:

The Molekule might be better at capturing VOCs, but they do not provide convincing evidence for it. The other information on their site is so bad that it makes me skeptical of this claim.

Smart Air

So what’s an air breather to do?

After reading this Molekule air purifier review, you might be wondering where to turn to for clean air.  To answer our original question, it seems the Molekule purifier is not worth it and is full of false claims.

I’ve been nerding out on purifiers ever since that 2013 Beijing airpocalypse. If I can sum up all of my testing into one message, it’d be this:

Air purifiers are shockingly simple. They’re a fan and a filter. Cheaper purifiers perform just as well—and often outperform—the ridiculously expensive machines.

So brush aside marketing claims, beautiful Nordic families living in all-white homes, and keep your money.


Air purifier advertisement BlueAir


Instead, check out any one of several sources of independent purifier tests and choose the best combination of effectiveness and price. I outline several sources of tests here:

What is the best air purifier on the market today?

Breathe safe!

P.S. I’ve ranted for too long about Molekule’s claims, but please indulge me the claim at the top of their homepage.


Molekule air purifier review


Finally a purifier “that actually works.” Click on the link above to see dozens of purifiers that cost far less and “actually work.”


View the original article on Quora here.

Get Your Free Guide to Breathing Safe

Join the thousand keeping up on the latest research & knowledge on how to breathe safe. Sign up now and receive a free guide to breathing safe!

Notify of
Inline Feedbacks
View all comments

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