Comment by phnofive

> HEPA filters are good at capturing both particles smaller and larger than the 0.3 micron test standard

That is due to MPPS - the only thing that matters is the actual reference particle size, not larger or smaller particles, as these are ultimately easier to filter. That is, particles between 0.2 and 0.3 microns are the most difficult to effectively filter out.

> their focus is on PM2.5

Which doesn't mean it doesn't trap 0.3 micron particles, as PM2.5 is Particulate Matter up to 2.5 microns in size, not 2.5 microns and up.

There are inconsistencies between their main air filter recommendation article and the specific review; if you haven't, read the article about the IKEA filter here: https://www.nytimes.com/wirecutter/blog/ikea-fornuftig-air-p...