Some patients experience respiratory and eye allergy symptoms such as sneezing, runny nose, itchy nose and eyes, coughing, difficulty breathing, asthma, and swollen eyelids during the season when various plants are in bloom. This is most likely caused by pollen wafting in the air being inhaled into the respiratory tract or coming into contact with mucous membranes, hence the term hay fever. The pollen that causes hay fever is mainly tree pollen in the spring and weed pollen in the summer and fall. A study of airborne pollen sampling in Heilongjiang Province by the Second Hospital of Harbin Medical University found that: in the air of Heilongjiang Province: the pollen with higher concentration in spring is poplar and willow pollen, and the pollen with higher concentration in summer and autumn is the pollen of Artemisia (Artemisia grandis, Artemisia annua, Artemisia mugwort), grass (commonly known as Lala Yang), quinoa (commonly known as ashwort), sunflower, etc. The symptoms caused by pollen in spring are relatively mild, while the allergy symptoms caused by pollen in summer and autumn are more severe and last longer. Pollen dispersal is closely related to climatic factors. In windy and dry weather, the pollen concentration in the air is high and the patient’s symptoms are heavy, while in rainy and humid weather the pollen concentration is low and the patient’s symptoms are light. In northern China, pollen has become an important cause of rhinitis and asthma. A large sample study at Peking Union Medical College Hospital found that the onset of hay fever in summer and autumn is mainly concentrated in young adults, and 15-34 years old is the high incidence of pollen-induced rhinitis in summer and autumn; 25-44 years old is the high incidence of asthma. 37% of patients with hay fever rhinitis will develop seasonal asthma within 5 years, and 46.7% will develop it within 9 years. asthma. The clinical symptoms of summer and fall pollen-induced asthma are mainly episodes of coughing, breath-holding, wheezing, aggravated by activity, and in severe cases, inability to sleep at night, and even emergency treatment with intravenous aminophylline or glucocorticoids. Not all clinicians are aware that pollen can cause severe asthma in summer and fall, and most patients who have frequent attacks during this season are misdiagnosed as having infectious asthma and treated with large amounts of antibiotics. Repeated intravenous administration of high doses of antibiotics and glucocorticoids can pose many unnecessary medical risks to patients. So how to prevent and treat hay fever? During pollen season, go to places where grass and trees are abundant, stay inside and close windows and doors as much as possible. Wear a mask when you go out, and if your eye symptoms are severe, bring wind goggles. When eating fruits, you should be more careful because there is cross-allergy between some pollens and fruits. For example, it has been reported in the literature that patients allergic to Artemisia pollen have an allergic reaction after eating peaches, and people allergic to birch pollen may be allergic to apples, etc. Because pollen spreads with the wind, it is difficult to completely avoid exposure. Treatment of hay fever can be done with antihistamines, decongestants, mucosal receptor agonists, topical or oral corticosteroids and allergen-specific immunotherapy. Among them, allergen-specific immunotherapy is the only method currently recognized by the World Health Organization (WHO) to stop the natural course of allergic diseases. Therefore, specific immunotherapy should be started as early as possible for patients with pollen-induced allergic rhinitis in summer and autumn to prevent its development into asthma. In particular, patients with asthma should be actively treated with specific immunotherapy to prevent further aggravation of asthma.