Common causative agents: cold, exertion or rain. More common causative agent: Streptococcus pneumoniae. Symptoms: Clinical onset is rapid, often starting with high fever and chills, followed by chest pain, cough, coughing up rust-colored sputum, dyspnea, and signs of solid lung changes and increased peripheral blood leukocyte count. The course of the disease is about one week, the temperature drops abruptly and the symptoms disappear. Imaging manifestations: congestion stage: X-ray may not have positive findings, CT can be seen as ground glass changes. In the solid phase: dense and homogeneous hyperintensities with clear borders when accumulating one lobe, and air-containing bronchial signs are visible within it, and dense shadows distributed in large lobes or lung segments are visible on CT, and air-containing bronchial signs are clearer. Absorption phase: scattered patchy faint shadow of varying size, and finally completely absorbed. Prevention: (1) Pay attention to the prevention of upper respiratory tract infections and strengthen cold tolerance exercise. (2) Avoid rain and cold, drunkenness, overwork and other triggers. (3) Actively treat the primary disease.