Various risk factors exist for pulmonary fibrosis (lung hardening). These include viral infections, exposure to tobacco smoke, genetic predisposition, and gastroesophageal reflux disease. Furthermore, certain demographic and environmental factors also increase the risk. Middle to advanced age, male gender, smoking, presence of emphysema, occupational exposures such as mining, farming, or construction work, and radiation therapy applied to the chest area during cancer treatment all elevate the likelihood of developing pulmonary fibrosis.