I used to smoke cigars in my home office, and the ventilation was pretty much set up for that. My duct fan was connected to an active carbon filter in the ceiling, to make sure the smoke would not be noticeable outside and leak back in when the bedroom windows were open in the summer months. That happened once, and the girlfriend did not approve.
Anyway; after I got the homelab properly set up, smoking cigars in the office just didn’t feel right… All that smoke drawn into the servers, heat-sinks, filters and so on. Never mind the lungs, think of the servers! So it was time to rebuild the exhaust ventilation system to better suit my new needs.