Mount Everest was first conquered six decades ago, but human waste left by those following in Sir Edmund Hillary’s footsteps is beginning to raise a stink.
Sherpas in Nepal are claiming that tons of waste left by climbers are polluting Everest's once pristine slopes and threatening to spread disease.
Human waste piling up over decades gives off an "unpleasant odour", Ang Tshering Sherpa, chief of the Nepal Mountaineering Association, told Reuters.
With hundreds passing through the biggest sight in the Himalayas each year, there is growing concern that the world’s highest mountain is becoming overcrowded.
Sherpa said that human excrement is now a bigger problem than the oxygen bottles, torn tents, broken ladders, and cans or wrappers also left behind on Everest.
"Discarded in ice pits, the human waste remains under the snow," he told reporters. "When washed down by glaciers (when the snow melts), it comes out in the open."
He added that the waste also poses a health hazard to people dependent on water from rivers fed by the region's melting glaciers.
Climbers say they are often forced to squat in the open or hide behind rocks to relieve themselves.
“Hygiene standards can be very low,” said Michelle Jana Chan, a Telegraph Travel writer and Himalayas expert. “Climbers are exhausted at the end of the day.
"When there is a queue to use designated facilities, they might dig a hole somewhere else or maybe they will not even bother to do that. The situation only gets worse. If you arrive to a dirty camp, you think it's okay to be dirty, too.”
She said that camps in the Himalayas, especially those on the way up to big peaks are suffering serious litter problems.
Litter on the slopes
Now Nepal has threatened stricter enforcement of penalties to persuade climbers to clean up after themselves and carry litter back to base camp.
A rule introduced last year required a deposit of $4,000 to be forfeited by any expedition from which a climber fails to bring back 8kg of rubbish and human waste.
Michelle Jana Chan said this “pack it in, pack it out” rule is tough to enforce however.
“Climbers, guides and the authorities all have to pitch in with some self- and peer regulation. Everyone should feel the duty - and if necessary, the pressure - to keep the mountains clean.”
About 300 mountaineers and as many Sherpa guides take to Everest's icy slopes during the annual climbing season, which begins in March and runs until May. Last year's season was cancelled after 16 local guides were killed in an avalanche.
Annual Eco Everest clean-up expeditions, led by Dawa Steven Sherpa since 2008, have retrieved 15,000 kg of rubbish, but there are no estimates of how much has been left behind.
A climber pauses on Everest
While some climbers carry disposable travel toilet bags to use in the higher camps, the waste from those who don't "is a health hazard and the issue needs to be addressed" he said.
Around 4,000 climbers have scaled Mount Everest in total. Snow shrouds the bodies of at least 260 who died trying.
In 2012, Nepali artists turned 1.5 metric tons of rubbish taken from Everest’s slopes into works of art as part of an awareness campaign to keep the summit clean.