So far I haven’t yet found anything which implicates PET-CF, unless you were to perhaps light it on fire and breath the fumes it gave off during combustion. I did a quick read of the Ultimaker MSDS for PET-CF, and if anything, it makes PET-CF sound almost benign
There was an interestng thread here:
which mentions someone who thought he became sick while printing PETG-CF. There was also further talk in that thread about how a number of people thought the carbon filter built into the X1 was not effective.
Also, another guy from the bambulab community said he got seriously sick from printing ABS and ASA an had to go to the hospital:
I have more links to chaase down, but if there’s a smoking gun regarding PET-jCF, I haven’t yet found it, at least not yet.
What I can agree with is that if you want to completely scrub the air in one pass, then I can certainly believe the tiny filter in the X1 will be inadequate for that. On the other hand, if you were in no hurry and could wait for it to cycle through the air say, 1000 times, then maybe by the end of that it will have reached past the point of diminishing returns,and doing more after that might likewise not have much of an effect.
Regardless, there are certainly chemicals that even activated carbon is unable to pull out of the air, so for that reason I’m inclined to think that venting to the outside is just obviously going to be the better way.