Fresh air might not be quite as fresh as we think. Viruses and bacteria get swept up into the atmosphere in enormous amounts, and now a new study has quantified that amount, finding that untold billions of microorganisms are raining down across the Earth every day.
For decades, genetically identical viruses have been found in very distant parts of the world. Scientists determined that the bugs were hitchhiking on airborne particles that are swept up into the atmosphere and carried long distances before being deposited back to the surface.
“Roughly 20 years ago we began finding genetically similar viruses occurring in very different environments around the globe,” says Curtis Suttle, senior author on the new study. “This preponderance of long-residence viruses traveling 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.”link