Kathmandu, Dec. 18 -- In 2000, Japanese climber Ken Noguchi launched what is widely regarded as the first organised clean-up campaign on Mount Everest, the 8,848.86-metre peak long celebrated as the ultimate symbol of human endurance. What he encountered instead was a mountain choked with trash.

"Before going, I always saw images of beautiful Everest on TV. I thought it would be like that," Noguchi later said in an interview. "But once I got there, I found litter everywhere."

Shocked by the scale of pollution, Noguchi organised fellow climbers to remove waste after completing his ascent. His team cleared nearly nine tonnes of garbage, including more than 400 discarded oxygen cylinders. Between 2000 and 2007, he helped collect around 90 ...