In natural forests and waterfalls, the content of negative ions varies depending on environmental and climatic conditions. Generally speaking, areas with high negative ion content mainly include natural environments such as forests, seasides, mountains, and waterfalls.

In forests, the negative ion content is usually high, reaching thousands per cubic centimeter. For example, Bama, Guangxi is known as the hometown of longevity in the world. The content of negative oxygen ions here is extremely high, reaching 2,000 to 5,000 per cubic centimeter. The average number of negative oxygen ions in the air in Shitai County, Anhui Province is 6,000-14,000 per cubic centimeter, reaching 35 times the World Health Organization's standard for clean air.

The content of negative ions in waterfall areas is also high because water molecules are split during natural processes such as the impact of waterfalls and the rolling of small waves to produce negative oxygen ions. In the ground crack scenic spot in Zhangjiajie, Hunan, the negative oxygen ion content is as high as more than 200,000 per cubic centimeter.

In mountainous and coastal areas, the negative ion content is also relatively high. The average number of negative oxygen ions in the air in high mountain areas is more than 14,000 per cubic meter, which is 15 times the normal value. In coastal areas, due to the crashing waves and evaporation of sea water, the air contains higher levels of negative ions.

To sum up, the negative ion content in natural forests and waterfalls varies by region and environment, but generally speaking, the negative ion content in these areas is higher, which has many benefits for human health.