An increase in transparency means in turn a decrease in the density of the lung fields, so that the transparency increases. The lungs are a respiratory organ and contain a lot of gas. Under the influence of diseases, such as chronic smokers and patients with chronic bronchitis, the gas is easily inhaled but not easily exhaled, resulting in excessive gas trapping in the lungs. Therefore, for these patients, when they progress to the severe stage, they will have chronic bronchial disease, emphysema, and further development of pulmonary alveoli, or cough or trauma, pneumothorax will occur after rupture, and emphysema, pulmonary alveoli, and pneumothorax will all show increased translucency, i.e., decreased density. Therefore, increased translucency of both lungs is depicted on the chest radiograph, most commonly as emphysema.