Nearly half of the tiny particles found high in the atmosphere over North America come from foreign lands, with 88 percent of that coming from Asia.
Nearly half of the tiny droplets and particles suspended high in the atmosphere over North America comes from other continents, an examination of satellite data reveals.
"That is a big number: half. I wasn’t expecting anything like that," study researcher Lorraine Remer of the University of Maryland says in a video released in conjunction with the new study on aerosols.
Specifically, the research team found that 70.5 million tons (64 teragrams) of foreign aerosols — which include naturally occurring dust as well as pollution — arrive over North America every year. Meanwhile, people and natural processes in North America produce 76.1 million tons (69 teragrams) of aerosols on their own, or 52 percent of the total.
There is another surprise as well: The research team, led by Hongbin Yu of the University of Maryland and NASA’s Goddard Space Flight Center, found that most of the aerosols are naturally occurring dust, not man-made pollution such as sulfates produced by the combustion of fossil fuel.