Ventilation in dungeons

[Generic Villain]

I'm a stickler for details. Obsessively so, in fact. My fortresses and strongholds always have ample storage space, pantries, a well, occasionally running water, a laundry room, workrooms, etc. But there's one stick in my craw: how can a fully subterranean, largely self-contained dungeon maintain fresh air for the occupants?

I have limited knowledge of airflow in closed subterranean places from reading about oldschool coal mines, and have two solutions: Solution one: the occasional brick in the dungeon wall is enchanted with transmutation magic to purify the air in the vicinity. Option two: discrete vents reach to the surface, and minor magic pulls in air from the outside and circulates it in the dungeon.

Yes, this is incredibly (perhaps overly so) obsessive on very minor details, but that's the stuff I love. Has anyone given thought to how the air in their deep, sealed off dungeons stays fresh and breathable? My third idea was to have a plant/algae/fungus farm to function as air purifiers, but the two dungeons I'm working on lack space for such a thing.

So yeah, there's my obsessive details-oriented quandary. Any thoughts or suggestions are welcome. Thanls.

[vagrant-poet]

I've always liked the magic scrubber option. Though often I don't make it a single brick, because it's not intended to be interactive.

A couple of Paizo dungeons explicitly do the air vent upwards thing too. Sometimes just for background detail, sometimes not.

I understand the instinct to really understand everything. But often players aren't interested in the air quality. And are happy enough with simple explanations if it does come up, in my experience.

It can be a good idea to create a list of things that are incongruous and see if there's a story to be told about the answers to those solutions. Otherwise structural magic that's time-consuming to put in place and solves the problem is a good shout. People also don't share all magic so it's possible to also say such a thing doesn't exist elsewhere because of access, funding, etc.

[Drejk]

Tiny portals to elemental plane of air.

[Generic Villain]

vagrant-poet wrote:

I've always liked the magic scrubber option. Though often I don't make it a single brick, because it's not intended to be interactive.

A couple of Paizo dungeons explicitly do the air vent upwards thing too. Sometimes just for background detail, sometimes not.

Hah, it's funny you mention both these. From my campaign:

"Additionally, several dozen bricks in these depths have been enchanted, essentially functioning as magic items that cannot be moved without destroying them. They function at caster level 3rd and radiate faint transmutation auras if such is detected for. These bricks magically refresh and circulate air in the Veinstone Citadel, and while it tends to be on the stale side, it is quite safe to breathe."

"...and despite the lack of windows, the air is fresh and flowing. This latter feature is thanks to a number of ingeniously built air vents that keep fresh air moving throughout the vast fortress, helped along by minor magical enchantments that draw air into the compound."

[Generic Villain]

Also I know that the PCs will likely never stop to question why they're able to breathe in an enclosed subterranean dungeon. Ever. But I have OCD and an obsessive attention to detail. I always include stuff like methods to produce running water, laundry rooms, and other boring but necessary features.

[Paradozen]

This might not quite be what you are looking for, but you could include ventilation as a potential new point for exploration for the party. It could have air sourced from a subterranean tunnel that the architects knew had reliable access to air and assumed led to the surface, but which in truth reaches down to the Darklands (or whatever analagous region exists in your setting, if one does). Darklands has creatures who breathe air, so there's a source of air somewhere down there, and it means the party could discover the ventilation system and pull the campaign in a new direction as a reward for attention to detail. Or later they could be pointed back to this fortress as they try to find a route to the Darklands by an allied architect who discovered this secret feature if the campaign ever tries to go that direction.

[TheGoofyGE3K]

Efficient oxygen- creating plants has always been my assumption. Like moss. Not the most exciting answer, but could be helpful in some dungeons