The air recirculation button in your car is one of the most commonly used—but least understood—features on the dashboard. Identified by an icon of a car with a circular arrow inside, this button tells your vehicle’s climate control system to stop pulling air from outside and instead reuse theair already inside the cabin. While it may seem like a minor setting, it plays a surprisingly important role in comfort, efficiency, and even air quality, depending on when and how you use it.

When air recirculation is turned on, your car cools or heats the cabin more quickly because the system doesn’t have to constantly condition new outside air. This is especially useful on very hot days when you’re using the air conditioner—recirculated air cools faster and reduces strain on the AC system, which can slightly improve fuel efficiency. It’s also helpful in traffic jams, tunnels, or polluted areas, since it prevents exhaust fumes, smoke, and unpleasant odors from entering the vehicle. Read more below