.Bacteria and viruses are swept up in the atmosphere in small particles from soil-dust and sea spray.Suttle and colleagues at the University of Granada and San Diego State University wanted to know how much of that material is carried up above the atmospheric boundary layer above 2,500 to 3,000 metres.The researchers also found the majority of the viruses carried signatures indicating they had been swept up into the air from sea spray.At that altitude, particles are subject to long-range transport unlike particles lower in the atmosphere.The viruses tend to hitch rides on smaller, lighter, organic particles suspended in air and gas, meaning they can stay aloft in the atmosphere longer."Every day, more than 800 million viruses are deposited per square metre above the planetary boundary layer - that is 25 viruses for each person in Canada," said Curtis Suttle, virologist at the University of British Columbia in Canada.The deposition rates for viruses were nine to 461 times greater than the rates for bacteria. "It is quite conceivable to have a virus swept up into the atmosphere on one continent and deposited on another," said Suttle, senior author of the research paper published in the International Society for Microbial Ecology Journal.The study marks the first time scientists have quantified the viruses being swept up from the Earth&Wheel lighter Manufacturers39;s surface into the free troposphere, the layer of atmosphere beyond Earth's weather systems but below the stratosphere where jet airplanes fly."Bacteria and viruses are typically deposited back to Earth via rain events and Saharan dust intrusions.The viruses can be carried thousands of kilometres there before being deposited back onto the Earth's surface, researchers said. However, the # rain was less efficient removing viruses from the atmosphere," said Isabel Reche from the University of Granada.Using platform sites high in Spain's Sierra Nevada Mountains, the researchers found billions of viruses and tens of millions of bacteria are being deposited per square metre per day.
