If you can get them into a shed or an outbuilding, that's 99.9% of the problem solved.
You can also enclose the printer. For example, the ender3 pro has a box bag that you can put the printer in. Solves the problem.
My custom printer has the activated carbon airfilter/fan. Its probably overboard, but I did have that in my workspace for a while, so it was worthwhile for the time. I have no good metric when the filters should be replaced... I don't know any way to monitor particulate load in a filter.
The filter in the X1 isn't good enough to filter much out at all really. It's more of a gimmick than a genuine filter solution. I've put mine in an out building and installed a shower fan in the wall which is connected up to a relay controlled by a Raspberry Pi. I've then got an air quality sensor that triggers it turning on.
Even that isn't close to being enough to filter it all out and I'd certainly not stay in the room for any length of time whilst it was printing.
I'd trust your nose. If you can smell it printing, it means you're smelling the outgassing of unburnt and burnt plastics.
You could also get a pm10 and pm2.5 air quality monitor for a more scientific measurement. Gasses won't trigger those, depending on what they are.. I guess you could make a forced air device with 20 sensors in it, but nothing on the market is like that.
As for limited exposure, it's probably not too bad. But uncovered in bedroom... Whole different story.
You can also enclose the printer. For example, the ender3 pro has a box bag that you can put the printer in. Solves the problem.
My custom printer has the activated carbon airfilter/fan. Its probably overboard, but I did have that in my workspace for a while, so it was worthwhile for the time. I have no good metric when the filters should be replaced... I don't know any way to monitor particulate load in a filter.