The research, which was conducted by a team of scientists from Spain, Canada and the US, aimed to find out how near-identical viruses managed to keep turning up on opposite sides of the planet.
By taking samples from high up in Spain's Sierra Nevada Mountains, they discovered that billions of viruses and tens of millions of bacteria were being swept up in to the planet's atmosphere, carried across vast distances and then deposited again on a regular basis.
"Every day, more than 800 million viruses are deposited per square meter above the planetary boundary layer - that's 25 viruses for each person in Canada," said virologist Curtis Suttle.
"Roughly 20 years ago we began finding genetically similar viruses occurring in very different environments around the globe."
"This preponderance of long-residence viruses travelling the atmosphere likely explains why - it's quite conceivable to have a virus swept up into the atmosphere on one continent and deposited on another."
