Air filatration

I researched a bit too, and unfortunately to the best of my knowledge, you're probably not going to be able to buy a filter with any guaranteed effectiveness for particles of the appropriate size range.

If you'd like to be cautious, which is valid given the health effects are currently unknown / unresearched (although the lack of detection or specific control in the history of general plastics manufacturing might indicate the likelihood of them being severe or even consequential is low), then take steps to minimise your dosage. I do the following:

* Operate in a well ventilated room
* If you're using an enclosure, let it air a bit before sticking your head in
* Spend time away from the printer when it's running happily
* Use PLA rather than ABS where appropriate for the application

Then keep up with the research, and if someone can find both a reason to filter them and a filter that can perhaps there's a then a technical control to implement.

Why not vent to atmosphere?

Yup, the carbon filters absorb a lot of the volatiles (smelly bits) - fortunately humans come with detection equipment built in for those!! From what I've read, if you're not burning plastic those fumes aren't as bad for you as they smell, but they're still not pleasant and keeping the dose down could only be a good idea.

(Incidentally, I note from your sig ggunners you're an expert with the SD2 and a fan of the smell? )

Not so much for UFPs - we can't smell them, the carbon filters probably don't filter them (or at least we don't know). I'll say it, I'm totally skeptical that they're even a problem in the first place. Note this is and can only be an opinion.

Venting out the window like a laser cutter (properly combusted plastic is hella bad for you!) is an option. I'd probably add a heater to the input air (after the blower) to keep the chamber temp up so I wouldn't lose that advantage of the enclosure - which makes me not really bothered to implement it.

That's how I do it but with a carbon filter and you don't smell a thing until I open the door.  There are many things we are exposed to everyday that are much worse for us than anything coming from our printers.