I have an exterior vent on the side of my house not connected to any piping within. You can look inside and see wood/concrete/insulation into the cavity between the basement ceiling and main floor. I'm guessing it was an old vent before basement renovations. The dryer and basement bathroom fan both vent to another wall.
After a recent infestation of wasps I want to know if there is any reason I shouldn't just seal it up.