In 2018, the concentration of negative oxygen ions in the air in the downtown area of Pu'er was 14 times higher than the “Fresh Air” standard of the World Health Organization. The annual average value was higher than the “fresh air” standard defined by the World Health Organization. Pu’er was awarded the title of “China Natural Oxygen Bar”. Pu’er is the city with the highest concentration of negative (oxygen) ions currently available in China.