ASA and ABS really need a good filtration. Like actual filtration, not what the enclosure has. I personally just run a duct to my window and vent outside.
This review [1] cites the absolute highest amount of emitted styrene in the studies they are reviewing to be 113 μg/min. Using [2] for simplicity with styrene's molar mass (104.15 g/mol), we get to a printer creating at most 0.024 ppm of styrene per minute per m3 of unchanged air. For comparison, the "work exposure limit (WEL) for styrene is currently 100 parts per million (ppm) averaged over an 8-hour day" [4].
In other words, as long as you have some air exchange in the room, you'd be orders of magnitude away from the safe work exposure limit on styrene.
It also makes sense, considering that it's a microscopic amount of molten plastic, whereas injection moulding factories work with vats of the stuff.
There are active studies on chopped CF inhalation/contact hazards, and the SEM images in the above post prove how it occurs.
A lot of plastics contain wide assortments of additives to obtain mechanical properties. Outdoor ventilation is absolutely preferable to filtration or smell reduction filters that does practically nothing about carcinogens.
PLA is comparatively low emission, but a slow cooking PTFE tube in many hot-ends is not something people should be around. ymmv =3
There are different kinds of carbon fibres. It'd be great if it wasn't just Prusa disclosing which type they are using or offering studies on their impact, but in the meantime we can just use CF Prusament to be sure: https://www.reddit.com/r/3Dprinting/s/nQ5zUwnrWZ
Most filters have limited effective life for VOC, and "safe" use is measured in a few hours at most. Venting outdoors into a fern/decorative-plant filled yard is the preferred option for both FDM and Resin printers. Most activated charcoal filters just reduce the smell, and do nothing about the the harmful parts even with HEPA14 filters etc.
Chopped CF filled FDM filaments are mostly a scam, but there are few PETG and ASA viable options:
One challenge designing a metal-printing process was making it safe for people without prior lab-safety training. Some 3D additive processes are simply just not practical for careless "yolo" consumers. =3
CF filled filaments aren't a scam, they just have different tradeoffs: more rigid, nice surface finish, and less warping (all useful qualities!), but also lower layer adhesion, lower tensile strength, and less toughness. It's not just anecdotal, Igor Gaspar collected a lot of hard data on that.
Apart from the reply you've already received, most the bad stuff like plastic nanoparticles in the air and many hard to detect VoCs are also rather blatantly an issue with PLA and other filaments.
People focus too much on smell as the only indicator.
