Yes, it is necessary to have an outside vent for a gas clothes dryer. Gas dryers produce combustion byproducts, including carbon monoxide and other gases, which need to be properly vented outside to ensure safe operation. Venting the dryer to the outside allows these gases to be safely expelled from the laundry area and prevents them from accumulating indoors, which can be harmful to human health.
Additionally, proper ventilation helps remove excess moisture and lint from the dryer, improving drying efficiency and reducing the risk of fire hazards. Lint buildup in the dryer and its exhaust duct can be a fire hazard if not adequately vented.
If you have a gas clothes dryer, it is important to ensure that it is vented to the outside according to the manufacturer's instructions and local building codes.