Pulmonary embolism is a serious disease caused by abnormal substances in the human venous system that enter the pulmonary artery and its branches with blood flow and become embedded in the pulmonary artery blocking blood flow. Sudden embolism of the main pulmonary artery often results in sudden death, while embolism of the middle and small pulmonary arteries can lead to hypoxemia and infarction due to ischemia of the lung tissue. Some patients with acute pulmonary embolism may develop thromboembolic pulmonary hypertension with inadequate treatment, so pulmonary embolism requires attention. In the past, pulmonary embolism was considered a rare disease, but with the development of medical technology and the popularization of knowledge about pulmonary embolism, the diagnosis rate of pulmonary embolism has increased significantly. The most common abnormal material in the blood that causes pulmonary embolism is thrombus, which is a mass formed by blood clotting. Under normal circumstances, blood in the body will not clot to form a thrombus. But in the following cases, blood is prone to coagulation and thrombosis. 1) Slow blood flow in blood vessels; 2) Damage to blood vessel lining; 3) Increase in blood viscosity. These three conditions often interact with each other, forming a vicious circle that eventually leads to thrombosis. The blood flow in the deep veins of human lower extremities is relatively slow, which is a good site for thrombosis. Because of the relatively slow venous blood flow, reduced exercise and high incidence of tumors in the elderly, pulmonary embolism was previously thought to be a disease of the elderly. However, recent studies have found that it is not uncommon for young people to have pulmonary embolism, and the reasons for this are closely related to poor lifestyle habits such as prolonged sitting on the Internet, reduced exercise and reduced water intake. When sitting for a long time, the lower limbs are bent and the blood flow in the veins of the lower limbs is blocked, and the blood viscosity is increased due to reduced water intake, which can trigger the formation of deep vein thrombosis in the lower limbs. In addition, long-distance travel is also a common cause of thrombosis. Because of the small space in cars and airplanes, long time lower limb bending and reduced drinking water can also easily induce lower limb thrombosis. Lower extremity venous thrombosis often results in pain and swelling of one lower extremity, while pulmonary embolism occurs as sudden respiratory distress, chest pain, chest tightness and fainting. Therefore, it is necessary to be alert to the occurrence of pulmonary embolism and seek medical attention when one leg swells and pains or sudden respiratory distress occurs after prolonged sitting or long-distance travel. Avoid prolonged Internet surfing and sedentary lifestyle. When traveling long distances, get off the bus halfway and move your legs and feet to promote blood circulation in the lower limbs. During the car ride, learn ballerinas to do the tiptoe action, the calf muscle contraction can also promote the lower limb venous blood return, avoid or reduce the occurrence of pulmonary embolism. Both the elderly and young people can reduce the occurrence of pulmonary embolism by exercising regularly and drinking water appropriately.