[terribleperson]

The ikea Fornuftig has a snap-on piece of cloth covered plastic that serves as a pre-filter, a replaceable particle filter, and a replaceable optional gas filter.

I've found that taking a shop vac and leaf blower to the pre-filter works quite well to get it clean.

That said, the Ikea air purifiers only make sense if you have a room that's about the right size for the Fornuftig. Their larger purifier is worse value, and you're better off looking at something like the Squair.