Use a mandolin or sharp knife to slice the apples into ⅛” thick slices.
Add the apple slices to a bowl and add the sugar, cinnamon, and salt over top. Mix together so all of the apple slices are coated in the cinnamon sugar mixture.
Transfer the apple slices to an air fryer and spray with nonstick spray. Cook at 375 F for 8-10 minutes. NOTE: keep a close eye on the chips and check them every couple of minutes to ensure none of them are browning too much. Shake the basket and/or flip the chips over to ensure even cooking.
Remove from the air fryer and let sit for 10-15 minutes to let the chips really crisp up. Sprinkle with extra cinnamon sugar before serving (optional) and enjoy!