1. External factors
Feel the evil of wind-cold, dampness and heat, in which wind is the main factor, often mixed with other evil factors that hurt people, such as wind-cold, rheumatism, wind-heat or cold-dampness, rheumatic fever and other evil factors.
(1) common cold, cold and wet: due to the cold and wet living and working environment, such as sitting in the wetland, wading in the rain, or working underwater for a long time, or going in and out of the cold storage, or feeling the evil of cold and wet in rainy and wet seasons. In addition, it can also be influenced by regional conditions, such as how cold it is in the north and how wet it is in the southeast, all because of the invasion of common cold and cold and dampness. For example, Zhang said in "On Confucianism, Kindness and Bibi": "This disease is mostly rainy at four o'clock, and it occurs when it is too wet in March and September. It is still a place where water condenses, hard-working people are exposed to the wind and rain, the sleeping place is soaked, and paralysis enters from the outside. "
(2) Evil of rheumatic fever: exogenous wind-heat mixed with dampness, or wind-cold-dampness arthralgia, which turns into heat for a long time, resulting in pathogenic combination of rheumatism and obstruction of meridians and joints.
2. Internal factors
(1) Improper work and rest: overwork, impaired vital qi, low body defense function, sweating after work, or taking a cold shower after sweating, and foreign evils take advantage of it.
(2) Physical weakness: physical weakness, lack of physical exercise at ordinary times, or lack of qi and blood after illness and postpartum, lack of health care, weak external defense, and foreign evils taking advantage of it. As Hebi said: "All of them are caused by physical weakness, qi stagnation and emptiness, and cold and dampness."