A long-term, continuing drought in the Sahel grasslands near the Sahara in Northern Africa has caused huge and more frequent dust storms in recent years. Hundreds of millions of tons of soil are being blown away every year, scientists estimate. And coincidentally, thanks to a new generation of Earth-observing satellites, the dust clouds can be seen and tracked as never before. On Feb. 26 of this year a NASA satellite photographed one of the largest dust storms ever observed. About as big as Spain, the brown cloud was seen leaving Africa, heading west across the Atlantic toward the Caribbean and the United States.
Smaller clouds make the trip more frequently.
But there's more than just dirt in the dust. Hitchhiking along are bacteria, fungi, probably viruses and pesticides, even radiation. We will do more as we can afford it. Griffin is nearly certain the samples contain viruses, too, but said that has not been proved. New equipment he has on order will determine one way or the other, he said.