12mg. The average content of negative oxygen ions in the gas exceeds 6.5438+0 million per cubic centimeter, and the highest can reach 37,500. These negative oxygen ions are called vitamins in the air, which can enhance human activity, improve human immunity and degrade harmful substances in the air. Xishuangbanna's tropical rain forest climate and rich vegetation resources make it a natural oxygen bar, attracting many tourists to breathe fresh air and enjoy a healthy journey.