When headache occurs when there is no air circulation, the main reasons for considering insufficient oxygen and functional diseases are as follows: First, insufficient oxygen: if it is in a confined space with a lot of human traffic, being in a confined space for a long time may cause oxygen deficiency and lead to ischemia and hypoxia, and patients may experience head boredom and headache, some of which are accompanied by nausea and vomiting. At this time, if the window is opened to ventilate or to a place with air circulation, the symptoms may be quickly relieved. Second, functional disease: If it is a young patient, ask the patient whether there is panic, chest tightness, or whether there is mental tension and other factors. Some patients with functional diseases are more sensitive and may have headache in places with poor air circulation. Therefore, if headache occurs when there is no air circulation, mainly consider the causes of the above two aspects.