Comment by wabain

This article falls into the trap of conflating the Wirecutter's misapplication of filtration standards with irrelevant minutiae about which terms and diameters they cite for the filter classes. So alongside a pretty cogent description of how fine-matter filtration works by particle size, there's the claim that "a 'PM2.5 filter' … isn’t a thing," despite the PM2.5 class of fine particulate matter being the range specifically mentioned in the Ikea product description in the screenshot. A cursory search will turn up lots of results for filters which show that this is a pretty common term. Where the Wirecutter review actually goes wrong is in taking 2.5 microns as the lower bound of the particulate range, whereas it's conventionally the upper bound.

Then there's the idea that "Neither size mentioned (0.3 microns or 2.5 microns) has any relationship to either of the design specs" [the EU E12 and H13 standards]. When I google "hepa" my first hit is a US EPA page giving the specification for the most penetrating particle size of HEPA filters as 0.3 microns, rather than the 0.15 microns given in the article (from the empirical research or EU standards, I'm not sure which). This is from North America, but then, the Wirecutter is an American review site. It's worth considering this kind of (IMO) misfire in light of the article making the least charitable possible inference, that the Wirecutter deliberately set out to discredit the Ikea product because it couldn't give an affiliate link.

[1] https://www.epa.gov/indoor-air-quality-iaq/what-hepa-filter