The development of asthma is associated with exposure to certain allergens and irritants and is strongly influenced by environmental factors. On the other hand, normal individuals do not develop symptoms after exposure to these factors, suggesting that inter-individual differences are also important factors in the development of asthma. It is now believed that the onset and exacerbation of asthma is the result of a combination of environmental and individual factors. Individual factors include: ① Genetic factors: the prevalence of asthma is significantly increased in the offspring of patients with asthma; ② Gender: asthma is more common in males than females during childhood and in females after puberty; ③ Race: the prevalence is lower in Chinese than in Caucasians and Blacks; ④ Obesity: obesity may be one of the risk factors that increase the development of asthma; ⑤ Birth, early neonatal life experience: prematurity (gestational age <35 weeks), birth The incidence of asthma is increased in infants weighing <2.5 kg, and early breastfeeding after birth may reduce the chance of asthma. Environmental factors include: ① frequent exposure to allergens such as mites, fungi, pollen, etc.; ② air pollution; ③ exposure to occupational allergens such as breeding, chemical industry, printing and dyeing industry, etc.; ④ infection: respiratory syncytial virus (RSV) infection is strongly associated with wheezing symptoms in children; ⑤ family size: members of the extended family are less likely to develop asthma; ⑥ living conditions: high indoor humidity in the home is a risk factor for asthma (6) Living conditions: high indoor humidity in the home is a risk factor for the onset of asthma; mood swings: mental stress may be one of the triggers for asthma attacks.