Pulmonary fibrosis is a condition that often results in shortness of breath and a dry, hacking cough that won't go away, among other symptoms. The condition is the end result of long-term inflammation and an abnormal buildup of collagen within the supporting structures of the lung (the interstitial tissue). Causes of pulmonary fibrosis include radiation, chemotherapy, and long-term exposure to certain inhalants, such as dusts or toxic gases.