A number of conditions can cause scar tissue in the lungs, and while some are progressive conditions, others result in the development of a limited amount of scarring. Some individuals diagnosed with lung cancer develop scars in the tissue of the lungs after the tumors are removed and healed. Other, progressive diseases such as pulmonary fibrosis continue to build scarring around vital parts of the lung tissue.

When an individual undergoes radiation therapy for lung cancer, the tumors in the lungs are bombarded with radiation. This radiation is designed to eat away at the tumor, but in doing so it can also damage nearby blood vessels and air sacs. As these areas heal, it can often cause the formation of scar tissue in the lungs. When the radiation is stopped and the tumor is removed, the scar tissue will stop forming.

Other conditions result in the formation of scar tissue that gets progressively worse. Pulmonary fibrosis, also known as interstitial pneumonitis, occurs when the tissues of the lungs swell and begin to form scar tissue around the air sacs. This can be caused by the individual repeatedly being exposed to microscopic substances that cause tiny holes in the tissues of the lungs. The body responds by patching the holes, and with continued exposure and the buildup of scar tissue, the lungs can lose some of the elasticity that allows them to expand and contract with each breath.

Many individuals who develop pulmonary fibrosis do so through their jobs. The inhaling of chemicals, asbestos, minerals, or even types of mold can result in scar tissue in the lungs. This is also one of the most avoidable conditions that results in scarring, as much of the exposure can be limited by proper equipment and masks. A condition called chemical pneumonia can develop with prolonged exposure to toxins that cause inflammation and irritation in the lung tissue. Scar tissue in the lungs is one of the ways the body combats this intrusion.

Damage to the lungs can also result in scarring, from an accident or physical injury or from surgery performed because of another condition. Persistent inflammation or the presence of tumors can cause irritation in the lungs, which in turn results in the collection of fluid along the surface of the lung. When this fluid is drained, scars can form where the procedure was done. Outward trauma to the lungs, such as a puncture or smoke inhalation, can also be responsible for the buildup of scar tissue in the lungs as a healing process. In some cases, bacteria that enter the body in another area can settle into the lungs and damage the tissues there, resulting in the body developing scar tissue to heal the wounds.