I'd put a vent. You don't want condensation on the walls if you can help it. No air and moisture is a good recipe for mold. You can cut a new exhaust opening in the roof to vent it outside. You don't want the added moisture in the attic either. This is another place toxic molds can grow.
If anything get a quiet exhaust fan and vent the air into house, where it can pick up cross ventilation.
If anything get a quiet exhaust fan and vent the air into house, where it can pick up cross ventilation.
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