She added that safety matters the most, rather than reaching the summit.

At an altitude of 8,500 meters, she was once hit by a small stone falling from above, bruising an eye. She was also shocked that an overseas mountaineer she had chatted with in the morning had died suddenly in the afternoon.

Huang also came across the bodies of climbers, and said she hoped that such remains could be buried properly in the future.

"When you are climbing, it's a struggle between whether to give up or stick at it. You need to be strong-willed," she said.

Experienced mountain guide Bao Yifei said it is important to have a good system to transport waste from high altitudes and to introduce regulations for climbers to adhere to.

Bao works for the Shanghai company Land Summit, which offers services for mountaineers aiming to conquer the Seven Summits, the highest peaks on each of seven continents. Bao has conquered all of them. The company helps Chinese clients climb Qomolangma from the South Face in Nepal.

Bao said that of the Seven Summits, the Vinson Massif in Antarctica has the strictest rules - all human waste must be transported to South America. Mountaineers can only urinate at marked sites, their feces must go in special bags and all garbage must be taken back to base camp.

In Nepal, as in China, each climber has to collect and bring back with them 8 kg of waste to base camp. Bao said they have removed garbage including food packages and even oxygen cylinders from mountains, adding that some climbing companies have strict rules for their clients to follow.

Bao said it is expensive to climb Qomolangma because material supplies are needed as well as a professional team, including porters, guides and cooks. "The more you spend, the more help you will get. That's why the cost can vary."

He said the company's clients have the funds required, are physically strong and have two months' free time to climb Qomolangma. The most important thing is that they believe conquering the mountain is valuable for them.

"To prepare, you need to exercise and climb mountains of different altitudes in advance. In addition to having an experienced team, you should also be aware of the risk of death. Every year, climbers die on the mountain," he said.