What is the consequence of lung fibrosis on gaseous exchange?

Fibrosis is the formation of scar tissue due to injury of the alveolar walls (small sacs at the end of bronchioles that are responsible for gaseous exchange), from smoking or other small particles. Due to this scarring, the usually efficient single-cell thick alveoli now become dense and thickened. This increases the diffusion distance between the atmosphere and the blood in the lung capillaries which, according to Fick’s law, decreases the rate of diffusion of oxygen into the blood and carbon dioxide out of the blood, even if there is an adequate diffusion gradient.
[Fick’s law states that rate of diffusion is proportional to (surface area x diffusion gradient)/diffusion distance]