In terms of clinical symptoms, if a child or adult develops facial or limb numbness and weakness, aphasia or slurred speech, blurred vision or transient black haze, epilepsy, etc. for unknown reasons, it is important to consider whether it is smog, and further examination is needed at a hospital. In addition, some children with mental retardation, slow development, and some mental abnormalities should also be examined in the hospital to rule out whether it is caused by smog. In terms of imaging, if the cranial CT and MRI images diagnose cerebral ischemia or cerebral hemorrhage, further cranial CTA or MRA examinations should be performed, and if bilateral internal carotid artery stenosis or occlusion with smoke-like vessel formation is found, the preliminary diagnosis of smog can be made. To confirm the diagnosis, whole brain angiography DSA should be performed, and cerebral angiography is the gold standard for the diagnosis of smog. The diagnosis can be confirmed by clinical symptoms and cranial CTA or MRA findings in children without whole brain angiography DSA. In terms of cerebral hemodynamics, a series of further tests such as cerebral perfusion CT and PET are needed to further understand the cerebral blood flow and cerebral metabolism of patients, evaluate the degree of cerebral ischemia and guide the treatment.