Is the Molekule really better than air purifiers already on the market?

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

 

Molekule air purifier review

 

He asked not because he’s interested in purifiers, not because I’m some PhD in fluid mechanics (I’m a cultural psychologist, not a physicist), but because I’ve been building and testing DIY air purifiers ever since a Beijing airpocalypse in 2013 had me coughing for weeks.

Here’s one of the more “beautiful” machines I built and tested:

 

DIY air filter HEPA

 

Why would a psychologist spend four years building and testing purifiers? Because the air outside my Beijing apartment was “beyond index”…

 

Beijing air pollution

 

…and the view in my online shopping cart looked like this.

 

 

I was scared, and these companies were saying that clean air costs $500 or $1,000. Soon I found I could make my own purifier for about $30 that effectively reduced even tiny PM2.5 particles in my room (what’s PM2.5?).

 

DIY filter room test

 

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, not because they’re high profit margin, but because the technology is better.

 

IQ Air store

 

That’s the backdrop that was in my mind as my dad handed me his iPad, and I clicked on the Molekule ad.

 

Molekule 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).

Bottom line: Their claim to superiority about particle sizes is false.

 

Molekule 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 technology to kill that bacteria.

 

 

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.

Bottom line: 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.

 

Molekule Claim #3

Molekule says HEPA filters can’t capture viruses because they’re too small. But their 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 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 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.

Bottom line: 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.

 

So what’s an air breather to do?

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.

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Ann

Yay! Chicago Booth! Fascinating debunking of Molekule. From a fellow Maroon.

Steve Marcos

Thank you for saving me $700
Great review.

Bev

Thanks for helping me to be more analytical about this purifier. I really am looking to clean second hand smoke from a neighbor. Any ideas on that? Thanks!

Tony

I appreciate this review. It all sounded sexy. but immediate alarm bells about how it kills microbes or whatever, but… it still needs filters that of course you have to keep paying for. Just read another “review” that was clearly an influencer-paid post of just saying “well, buy it, because…”

This reassures me that i’m not just cynical.

Uccello

Great article, loved it.