Mild infection of the lungs is also pneumonia. Mild infection of the lungs only means that the infection is mild and not serious, but the mucous membrane of the lungs is still invaded by viruses, bacteria, mycoplasma, chlamydia, rickettsia, and pathogens such as Mycobacterium tuberculosis, fungi, protozoa, and parasites, and the mucous membrane of the lungs shows relatively limited and mild changes of congestion, edema, and exudation of inflammatory secretions, which still belong to Pneumonia is still in the category of pneumonia. Patients may have a mild cough and sputum and may be able to see relatively limited and small lesions by taking X-rays or CT of both lungs.