Li Shizhen described Chi Ai in his "Compendium of Materia Medica" as follows: "Since the Chongzhen era, Chi Ai from Qi Zhou has been regarded as the superior variety. It is used as a precious commodity and is highly valued throughout the world. It is called Chi Ai." 

The plants of Qixian Ai, produced in Qixian County, are tall, typically reaching a height of two and a half meters. Their leaves are very thick and have a high oil content. Qixian Ai is also known as the top of the "Qixian Four Treasures" due to its unique medicinal value. It is a long-standing and authentic medicinal herb with a history of over 500 years. 

The freshly picked fresh mugwort leaves are the oldest fragrant materials. Ancient people often hung fresh mugwort leaves in their homes to repel insects and ward off evil spirits. Fresh mugwort leaves are often used to extract essential oils, warm the meridians and promote circulation, and have a fragrant and soothing effect. 

Ai is one of the most yang-nourishing medicinal herbs. It is classified into fresh ai, aged ai and cooked ai. 

Fresh mugwort is the naturally dried mugwort leaves; aged mugwort is the fresh mugwort leaves that are stored in the dark and gradually age, with the excessive volatile oils in the leaves being eliminated to form; cooked mugwort is the mugwort fiber made from the aged mugwort leaves. 

The medicinal value of Ai (grass) mainly lies in its pungent taste and its strong dispersing effect. It is often used in making decoctions, baths or foot soaks, as it helps to dispel dampness and cold. 

Roasted mugwort has a mainly bitter taste and its warming effect is not as strong as that of raw mugwort, but it is more hot in nature. 

After undergoing processes such as carding and twisting, the raw mugwort is transformed into mugwort sticks and mugwort cylinders, which are used for moxibustion. Besides relieving cold and dampness, it can penetrate the tendons and bones, nourish yang and dispel cold. 

Ancient physicians said, "When medicine fails to work and acupuncture cannot reach the affected area, then moxibustion must be used." The main effect of moxibustion is to warm the meridians and unblock the circulation, promote qi flow and activate blood circulation. Traditional Chinese medicine records, "When it is warm, it moves; when it is cold, it凝s." Especially for some diseases caused by blocked qi and blood circulation， moxibustion therapy can allow high temperatures to penetrate the muscles， bones， and meridians of the body， warming up the cold qi and blood， and making their circulation more smooth. 

"Seven years of illness, treat with three years of mugwort." The use of aged mugwort for moxibustion is a principle repeatedly emphasized by medical experts throughout history. Mugwort that has been stored for more than three years has completely degraded its harmful components and can generate beneficial components in the form of alcohols. However, if the aged mugwort is stored for an excessively long time, its effective components will be lost. 

In Qichun and even in the eastern part of Hubei Province, many children take an "ayi bath" as their first thing after birth. They take a bath by using water boiled from dried atractylodes, which can help detoxify. Moreover, many elderly people would take an "ayi bath" before being buried in coffins after their death. This is called the "nirvana bath" in the local area.