Viruses, bacteria and other invisible invaders have been making news lately — and not just because we’re in the thick of a particularly intense influenza season. Between a stomach-churning DIY experiment with a public hand dryer [here’s that full story, but steer clear if you’re even slightly germaphobic], to recent scientific evidence linking prehistoric viruses to human consciousness, it’s hard to avoid the idea that there’s absolutely no escape from these microscopic menaces.
With that info in mind, it shouldn’t be much more of a shock to discover that hundreds of millions are literally raining down from the Earth’s atmosphere each day.
Phys.org shared a new study between researchers in the US, Canada and Spain, which reveals the first scientific evidence that roughly 800 million viruses are being pulled up into the Earth’s troposphere each day — above the level where most weather systems form — where they can be carried thousands of miles before falling back to the planet surface.
“Roughly 20 years ago we began finding genetically similar viruses occurring in very different environments around the globe,” reports University of British Columbia virologist Curtis Suttle, one of the lead researchers in the study (the results of which were published in the International Society for Microbial Ecology Journal).
“This preponderance of long-residence viruses travelling the atmosphere likely explains why,” Suttle writes, “it’s quite conceivable to have a virus swept up into the atmosphere on one continent and deposited on another.”
The team determined that micro-organisms “hitch rides” on dust particles and mist, carried up to Earth’s atmospheric boundary layer, around 2500 to 3000 meters above the surface.
“Bacteria and viruses are typically deposited back to Earth via rain events and Saharan dust intrusions,” said University of Granada ecologist Isabel Reche, one of the paper’s co-authors. “However, the rain was less efficient removing viruses from the atmosphere.”