Don’t forget your tissues when mountaineering, as microbes from coughs and sneezes can be stored in the ice for centuries, a study finds.
Researchers at the University of Colorado Boulder analyzed soil samples from Mount Everest and found microbial DNA associated with humans.
Including the bacteria to which these belonged Staphylococcuswhich is associated with food poisoning and pneumonia, and Streptococciwhich causes sore throat.
Most of the microbes they found were thought to be dormant, but had been preserved in “freeze collection zones” near areas of human activity.
This finding supports the idea that extraterrestrial life could exist on other frozen planets, the scientists say.
Microbes from mountaineers’ coughs and sneezes may be preserved in the Arctic for centuries, a study finds. Pictured: View of the South Summit from South Col Camp

Researchers at the University of Colorado Boulder analyzed soil samples from Mount Everest’s South Col and found microbial DNA associated with humans pictured: the surface at the soil collection site
Dr. Steve Schmidt, senior author of the new paper, said: “We may find life on other planets and cold moons.
“We have to be careful not to infect them with our own.”
In the past, researchers have studied the soil in the coldest regions on Earth, but they have rarely discovered significant amounts of human-associated microbes.
Indeed, they have never been able to conclusively identify these microbes in samples collected above 26,000 feet (7.9 km).
But for the new study, published in Arctic, Antarctic and Alpine Researchthe US-based team analyzed the soil using state-of-the-art gene sequencing technology.
Their samples were collected from Everest’s South Col during the 2019 National Geographic and Rolex Perpetual Planet Everest Expedition.
This was the most comprehensive scientific expedition to Mount Everest in history and included the installation of the two highest weather stations in the world.
The South Col is the rocky canyon between Everest and Lhotse peak, and the last stop for mountaineers before embarking on their journey to the highest mountain in the world.
Explorers with the expedition traveled as far away from camp as possible to collect soil samples, before they were analyzed in the laboratory.
Scientists were able to identify almost all active and dormant microbes in the sample through their DNA and determine their genetic diversity.
They expected to find some of them, as they have been detected in other extreme, high-altitude locations.
These are particularly hardy microbes, as they thrive in low temperatures, high UV exposure and with little water availability.

The soil samples were collected from the South Col during the National Geographic and Rolex Perpetual Planet Everest Expedition 2019. Shown: Map showing the sampling location along the Everest ascent route

Scientists were able to identify almost all active and dormant microbes in the sample through their DNA and determine their genetic diversity. Pictured: sampling location
One of them, Naganishiawas by far the most common in the South Col samples.
However, they also found unprecedented levels of human-associated microbes left over from mountaineers’ sneezes and coughs.
“There’s a human signature frozen in Everest’s microbiome, even at that altitude,” said Dr Schmidt.
Their existence was not surprising, given the number of adventurers passing through the South Col and how easily germs spread.
But their diversity indicated that the microbes were likely dormant and had not been killed off by the harsh conditions of the Himalayas.
This came as a shock, because these microbes evolved to survive in the warm, wet environments in our noses and mouths.
The researchers say these may have been left behind by explorers decades or centuries ago, suggesting that the impact of human activity on the mountain is greater than previously thought.
The authors wrote: ‘Our data suggest that the South Col and other extreme high-altitude environments may be deep-frozen collection points for deposited organisms, including human-transmitted contaminants that may never leave once they arrive.’