If a child or adult develops numbness and weakness of the face or limbs, aphasia or slurred speech, blurred vision or transient black haze, or twitching of the limbs for unknown reasons, it is necessary to consider whether it is a smog disease, and further examination is needed at the hospital. In addition, some children are mentally retarded, slow to develop, partially mentally abnormal, sometimes crying or nervous after appearing aphasia, fall head, hand can not hold things and other abnormal performance, also need to go to the hospital to check to rule out whether it is caused by smog. Smog can be divided into two types, one is ischemic smog and the other is hemorrhagic smog. In the milder cases, transient cerebral ischemic attack occurs with headache, twitching of limbs, weakness of limbs, speech impairment, abnormal sensation and change of visual field, etc. The above symptoms can last for a few seconds, minutes or even hours, and can disappear completely without treatment. In severe cases, cerebral infarction or cerebral hemorrhage may lead to hemiplegia, aphasia, coma or even life-threatening. When these symptoms occur, the cause should be investigated promptly. If the cause is not clear, think about adding a cranial MRI angiography MRA to rule out smog.