So what do we have here? A vent section that has fallen, thus spewing poisonous exhaust gases into a space beneath somebody's apartment. Those gases include carbon monoxide, which can both kill outright, and cause brain damage by depriving the brain of oxygen. Tenants may experience headaches for no apparent reason.

The cause -- at least of the fallen vent? Vent tape was used here. Seems like a good idea, but it's not because with time and heat, it can unstick. Self-tapping screws are a better idea. They're less likely to become unstuck.