How safe do you think it is to run an SLA 3D printer in the bedroom? I am planning to run Mi Air Purifier 3H/C while the printer is running, I am also thinking about adding this inside the actual printer (Elegoo Mini Air Purifier with carbon filter).
Is this safe or still too risky?
SLA/DLP printer resins contain skin irritants inside the solvent, and those create rather noxious fumes. As described in Best way to deal with Resin Printers in your living space that can become a health hazard, and can result in pulmonary irritation. Those irritants are molecule sized organic compounds, and even the best filters require an industrial-sized filter stack to catch everything.
In industrial manufacturing, rooms with resin in them usually require PPE that includes at least basic breathing protection, so having it in your bedroom, where you spend on average 4 to 8 hours a day, does expose you to more than the maximum allowable dose for an industrial worker.
Working with liquid resins is like working with 2 component glues: as careful as you are, you'll have some spillage or rests on trays. These need to be handled, and while with very high viscous epoxy one might get away without gloves and low-level PPE on a small level, the very fluid resin and the IPA used to wash your prints make spillage and droplets escaping the confinements where they belong a problem that is not just academical but bound to happen.
A dedicated wash-and-cure area for your resin 3D prints in somewhat close proximity to the printer and both outside of your sleeping environment is something that is highly advisable.
While lower irritant resins have come to the market since 2020 that have less odor and release fewer noxious solvents, the best way is still to minimize exposure and thus put the resin printer in a room that isn't your bedroom.
I'm running an Elegoo Saturn in a spare room, the smell is barely noticeable.
People tend to be over cautious about these things. Particularly Youtubers, because of fear of litigation, and because they tend to be at close quarters to resin for long periods of time.
It's perfectly safe to have a resin printer in a bedroom so long as you run the printer next to an open window, and keep the cover on.
My advice would be to store your resin separately (in a garage, for example) and to cover the tank with a proper snap on cover (or better yet to pour the majority of the content back into a bottle and store it outsides) over night.
Don't try to run the printer while you are sleeping. Not because of the fumes (which I would be concerned about) but because it will absolutely destroy your ability to get a good night's rest due to the repetitive noise.
For me, it's actually the IPA fumes which are the biggest problem.
