Traditional Chinese medicine (TCM) emphasizes the unity and harmony between nature and the human body. The theory of TCM medicine believes that human beings rely on all things on earth that surround them in order to survive. Hence, it is important for people to grow and develop in accordance with the laws of the four seasons. TCM describes the normal climatic changes in the four seasons as the "six qi", which include wind, cold, heat, dampness, dryness, and fire. However, abnormal changes in the six qi, e.g. "being excessive" (such as extreme heat, extreme cold, etc.) or "being insufficient" (such as cold rather than warm in spring, and hot rather than cool in autumn, etc.), will make it difficult for the human body to adapt and become a pathogenic factor. Such conditions are referred to as "six excesses" or "six evils" by TCM practitioners. Among all, dampness is one of the "external evils" that causes diseases. Due to the humid climate, illnesses caused by dampness are quite common in Hong Kong. As the weather in summer is dominated by high humidity, people are more susceptible to diseases caused by dampness during the long summer.