People will feel dizzy if they stay in a closed room in the city for a long time, but we will feel refreshed when we come to forests, beaches, waterfalls and other places. This is the function of negative air ions. Air negative ions, also known as negative oxygen ions, refer to oxygen ions with negative charges when gaining excess electrons. It is formed by combining oxygen molecules in the air with free electrons. Natural discharge (lightning), photoelectric effect, fountains and waterfalls can ionize the surrounding air and form negative oxygen ions. Negative oxygen ions enjoy the reputation of "vitamin", "air vitamin", "longevity element" and "air vitamin" in the medical field.

Medical research shows that there is a positive correlation between the concentration of negative oxygen ions and human health (as shown in the following figure). When the number of negative oxygen ions in the air per cubic centimeter exceeds 20,000, it will have the effect of treating diseases.

The following data were collected by Professor Ye from Taiwan Province University of Science and Technology. Negative ion concentration unit in the table: one /cm3.

However, as long as the small-sized ecological negative ions produced in nature or simulated natural principles are equivalent to those in nature, this effect will be produced. At present, the technologies that can generate small-sized negative ions include ecological negative ion generation chip technology and nano-fullerene negative ion release technology. This kind of ion should be placed on the foot bath, and the effect is not very good.