It has been nearly a century since the first recorded efforts to reach the summit of the world's highest peak, Qomolangma, which is known in the West as Mount Everest.
The first successful ascent of the mountain, from the South Face in Nepal, was made by a British expeditionary team in 1953.
The desire to scale Qomolangma never dies. However, human activities have had a negative effect in the area in recent decades.
Authorities in the Tibet autonomous region have been striving to tackle the problem of waste left at high altitudes.
They announced recently that to reduce the environmental impact on Qomolangma, climbers will be allowed to enter the region only in the spring, and their number will be limited to about 300 every year, including mountaineers, guides and support teams.
To protect the environment, since December travelers have been banned from all areas above the Rongpo Monastery, which lies at an altitude of 5,150 meters. But those with climbing permits are allowed to enter base camp in Tibet at 5,200 meters.
Last year, the Tibet Mountaineering Association welcomed 762 overseas visitors to climb the mountain, including 372 guides and logistics teams.
Authorities have planned to use funds collected from an annual service fee to carry out regular environmental protection work on Qomolangma.
The regional sports bureau has drafted a regulation aimed at improving garbage management on the mountain, and hopes it will take effect soon.
Sonam, secretary of the Tibet Mountaineering Association, who only has one name, said, "Our focus is for the mountain to be climbed in a scientific and green way, ensuring safety."
He said that awareness in China of environmentally protecting Qomolangma dates to the 1990s, both from the government and individuals.
"Compared with before, people - including mountaineers and local residents - are more aware of the importance of environmental protection. There are now many detailed measures to tackle waste in high-altitude areas of Qomolangma," Sonam said.
In Tibet, all mountaineers, guides and support staff members of climbing teams must each remove 8 kilograms of waste to the campsite, which lies at 6,500 meters.
Sonam said it takes two days for yaks to carry the waste from the campsite to base camp. This means a round trip of about four days. Within the area, there are 10 designated dump sites for people to place their waste, which are attended to every day by sanitation workers.
When garbage is transported to base camp, domestic waste is then taken by workers to a refuse processing plant. Waste related to mountaineering, such as used oxygen cylinders, tents and ropes, is recycled.
"When there are human activities, including mountaineering, there is garbage. As people only eat high-energy food in high-altitude areas, human waste is only a small part of domestic waste," Sonam said.
"Mountaineers conscientiously observe green discipline, and they rarely drop litter on Qomolangma."
Since 2017, local authorities have organized large-scale activities to remove garbage from high-altitude areas on the mountain, including that at dump sites.
According to a recent announcement by the authorities, toilets have been set up at the two campsites. Human waste was collected to provide fertilizer.
During three large-scale garbage collection operations last year, a total of 8.4 metric tons of household refuse, mountaineering and human waste, was disposed of.
This year, there will be three such operations during the climbing season from April to early June, each one lasting at least a week. They will be staged at the start, in the middle and at the end of the season.
Meanwhile, authorities plan to offer training on environmental protection and related skills annually, to encourage more people to take part in green activities.
Sonam said, "It's challenging to clean up waste at high altitudes, where just a small amount can be a great burden.
"Only professionals can enter areas above 6,500 meters. There are situations such as a lack of oxygen, and bad weather. Also, we have to use yaks to transport supplies in some high-altitude areas."
Sonam said the total cost per person to climb Qomolangma is about 400,000 yuan ($59,600) on average. Many charges have risen over the years, such as guides' wages and transportation fees.
This spring, authorities in Tibet plan to remove the remains of climbers on Qomolangma that have lain exposed at an altitude of more than 8,000 meters.
They will identify the bodies and contact families. The bodies will then be collected and buried at three sites away from the climbing routes, at above 8,000 meters.
The Ministry of Finance has promised to provide 4 million yuan to Tibetan authorities this year to remove climbers' remains and clean up high-altitude areas.
Huang Chunyan, who reached the summit of Qomolangma from the North Face in China on a 54-day mission in 2017, said: "In my view, Qomolangma is very clean. You can hardly see any waste along the climbing route."
She said that a recent online post had used unidentified photos to mislead netizens into thinking that Qomolangma is full of trash.
"Mountaineers respect and love nature, and most don't litter. I carried my own waste down from the mountain. Common garbage includes plastic bags and bottles. I also used special bags to collect my feces."
Huang is planning another trip to the mountain in May to join other volunteers in collecting garbage at altitudes of 5,200 to 6,500 meters.
"There are dump sites in the living areas. Our major task is to transport this waste manually and by using yaks. I am able to carry 20 kg at the most," Huang said.
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.
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