Contra Wirecutter on the IKEA air purifier

He can (and did) argue that this distinction doesn't really matter, but the distinction is still part of a well-defined standard that The Wirecutter didn't invent.

(With apologies to Wayne Gretzky)

> But it isn’t a true-HEPA purifier, or a very powerful purifier, period. It’s designed to capture PM2.5—that is, particles 2.5 microns in diameter and above, in contrast to the 0.3-micron HEPA standard. That means it’s optimized for larger airborne particles such as pollen and mold spores, rather than for very fine particulates like wildfire smoke, as HEPA filters are.

First, "True-HEPA" has no legal or scientific meaning, so that's not a great look.

Second, and a minor point, the 0.3-micron standard related to the US HEPA standard, not the EU one. It is true that acording to IKEA it doesn't meet the EU standard for HEPA (barely), but we don't know whether it meets the US one. Eliding the difference between different standards isn't helpful

Third, and more seriously, PM2.5 means particles 2.5 microns in diameter and smaller, not larger, and PM2.5 filters are designed to capture particles 2.5 microns and smaller. Mold spores are mostly 4 to 20 microns, pollen averages around 25 microns, so while the IKEA unit may or may not be good at filtering wildfire smoke, it is not optimised for mold and pollen and is probably terrible at it, so that entire line of analysis is just backwards.

That's a lot of errors to pack into a short passage, and it really gives the impression that the author doesn't really understand or care about the topic.

As for CADRs, the linked post digs into the tests pretty well, and I agree with the conclusion - they're not credible. Note specifically that they get a variance of over 2.4 times between tests, and in somes cases measure a CADR vastly higher than the manufacturers claimed CADR. If you're reading a benchmark of a new graphics card and someone ran a benchmark twice and got 100 FPS once and 240 FPS the second time, and they just shrug and pick the number most convenient for their conclusion, you'd probably think something was up.

(That being said, the linked post is a bit iffy too. I'd call out specifically that they could have done a better job of acknowledging that US HEPA standards are a thing, that PM2.5 filters are a thing even if they're not a standard, and that technically E12 filters aren't HEPA, even if that's an arbitrary distinction most people ignore. But they're quite right that the Wirecutter - on the review of the IKEA unit - does in fact seem to think air filters work like sieves. Certainly I can't think of any other explanation for that passage about PM2.5 being good for pollen!)

A concrete example is frequent flyer/travel blogs. I vaguely know the guy who runs the UK's largest one, I've met him in person several times, fairly nice bloke. He's worked very hard to build his site, publishes high-quality content, and is often the first to write about new places and routes of interest. His site has a thriving forum and allows comments on his posts.

He also pushes credit card offers and his site is littered with affiliate links.

Hmm, you say, that's OK, it doesn't necessarily mean he's lost his objectivity.

Except, his articles will say that the best way to book flight or hotel X is via offer Y (coincidentally in affiliate scheme Z, which is where the "book now" link sends you to). Then someone in the comments will pipe up to mention an alternative cashback route that is objectively better. He will delete that comment and any replies to it. So those who aren't aware of what's going on believe his article is the objective truth, and keep feeding the beast by clicking on his affiliate links. They miss out on all the better deals because they involve booking in ways that no-one's allowed to mention on his site.

This has happened over and over again. To me, affiliate marketing is basically a cancer.