Highest altitude microplastic found on land

Microplastics are small pieces of plastic that measure no more than 5 mm (0.2 in) that have risen in notoriety in recent years as a result of the growing threat they pose to the natural environment. The highest altitude on land at which microplastic debris has been retrieved to date is 8,440 metres (27,690 feet) above sea level during a scientific expedition in April/May 2019. The polymer fibres, at a density of 12 fibres per litre of snow, were found on the “Balcony” – a section on the South Col (aka Southeast Ridge) just below the summit of the world’s highest mountain, Mount Everest (aka Chomolungma, or Sāgārmatha). This research was conducted as part of the multidisciplinary Perpetual Planet Everest Expedition, organized by National Geographic and Rolex, with the findings published in the journal One Earth on 20 November 2020.

Five different types of plastic microfibres were found in snow taken from the “Balcony”: transparent acrylic fibre, red polyester fibre and blue polyester fibres. Suspected origins of the fibres are the clothing or gear (such as tents) of mountain climbers, or possible transportation by the wind from lower elevations.

Based on all 11 snow samples collected during the expedition, an average density of ~30 microplastic pieces per litre were counted; the most polluted sample was, perhaps not surprisingly, from Base Camp (the Everest site with the most human activity), with 79 particles per litre. Of the eight water samples taken from streams, microplastic occurrence was much lower at ~1 piece per litre. Almost all microplastic found on Everest were in the form of artificial fibres, though three larger fragments (two nylon, one polyester) were also detected.

Microplastic can either originate at that size (such as microbeads used in some beauty products) or be deposited from the wear/degradation of larger items containing plastic materials.

Other high-altitude records set during the Perpetual Planet expedition, which contained 34 scientists as well as support from experienced Sherpas and other local climbers, were the installation of the highest terrestrial weather station and the extraction of the highest ice core.

The microplastic aspect of the expedition and associated academic paper was led by Dr Imogen Napper of the University of Plymouth (UK), in collaboration with the University of Exeter (UK), the University of Maine (USA) and Tribhuvan University (Nepal).