Blood oxygen levels do not fall on rainy days in people with pulmonary heart disease. Cor pulmonale is a disease in which the structure and function of the heart are abnormally altered due to diseases of the lungs and pulmonary vasculature, as well as lesions of the thorax and other parts of the body. It may be related to causes such as pulmonary embolism, chronic obstructive pulmonary disease, and thoracic deformities. Pulmonary heart disease may present with symptoms such as dyspnea, chest pain, cough, hemoptysis, fainting, and even shock. It is possible that the oxygen level in the blood may be lowered due to a decrease in ventilation and air exchange in the lungs combined with a decrease in the heart’s ability to pump blood. When it is cloudy and rainy, there is no significant change in the concentration and content of oxygen in the air, so it will not affect the blood oxygen of people with pulmonary heart disease. Patients with pulmonary heart disease should breathe more fresh air, follow the doctor’s instructions to actively treat and regularly review the blood oxygen saturation, chest CT, electrocardiogram and other items, if there are uncomfortable symptoms need to consult a doctor in a timely manner.