I am often asked the question of what smog is. It’s no wonder, because smog is a disease that many primary care providers, not to mention ordinary patients, may not know about. For diseases such as diabetes and heart disease, patients usually do not ask their doctors what the disease is because it is too common and many people have some knowledge of these diseases. Smoke disease is a relatively less common disease, the incidence is relatively low, even once considered a rare disease, it is not surprising that people do not know. Therefore, when a patient asks this question during the consultation, I will explain it patiently to the patient, and sometimes I have to draw a diagram on the spot in order to make the patient understand it quickly. What is smog disease? Smoker’s disease is a cerebrovascular disease that is caused by chronic progressive stenosis or occlusion of the major arteries of the brain, followed by compensatory abnormal proliferation of the penetrating arteries at the skull base, forming a fine and fragile network of abnormal blood vessels at the skull base. These abnormal vascular networks appear as a cloud of smoke on cerebral angiography, so it is imaginatively called smog disease. Is smog serious? Smog is very serious and dangerous. It can cause both cerebral ischemia and cerebral hemorrhage. The narrowing or occlusion of the main arteries of the brain in patients with smog can cause poor blood supply to the brain, leading to cerebral ischemia and cerebral infarction, and severe cerebral infarction can be disabling or even fatal; while the abnormal vascular network formed at the base of the skull, with very thin and fragile walls, can easily rupture, causing cerebral hemorrhage or subarachnoid hemorrhage, which is also potentially life-threatening. Therefore, patients suffering from smog should be treated with surgery in time, and currently combined vascular bypass surgery is an effective means of treating smog.