A stream of airborne microorganisms, including marine viruses, bacteria and protists, circles the planet above weather systems but below commercial air lanes. Some peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from marine microorganisms in sea spray. In 2018, scientists reported that hundreds of millions of these viruses and tens of millions of bacteria are deposited daily on every square meter around the planet.
Compared to the sub-surface waters, the sea surface microlayer contains elevated concentration of bacteria and viruses, as well as toxic metals and organic pollutants. These materials can be transferred from the sea-surface to the atmosphere in the form of wind-generated aqueous aerosols due to their high vapor tension and a process known as volatilisation. When airborne, these microbes can be transported long distances to coastal regions. If they hit land they can have detrimental effects on animals, vegetation and human health. Marine aerosols that contain viruses can travel hundreds of kilometers from their source and remain in liquid form as long as the humidity is high enough (over 70%). These aerosols are able to remain suspended in the atmosphere for about 31 days.  Evidence suggests that bacteria can remain viable after being transported inland through aerosols. Some reached as far as 200 meters at 30 meters above sea level. It was also noted that the process which transfers this material to the atmosphere causes further enrichment in both bacteria and viruses in comparison to either the SML or sub-surface waters (up to three orders of magnitude in some locations).