Are your lungs permantly damaged even if you stop smoking after smoking for a decade?

Not necessarily: It depends on what kind of damage was present before you stopped smoking, and this varies highly between smokers, based on how much they smoke, how deeply they inhale, and genetic and environmental factors as well. The lungs can completely heal after smoking cessation, although the dark pigment will not go away. If damage has been done, some healing can also occur, but isn't usually 100%.