Photo: Leaves "Magnetized" by Air Pollution, Study Finds



Automobiles, such as this bus seen in a file photo, spew exhaust that deposits metallic fragments on leaves. Although such leaves wouldn't be physically attracted to a magnet, "magnetic" tree leaves along heavy traffic routes may offer a quick, cheap way to test for air pollution, an October 2009 study says.

Photograph by Don Tremain/Getty Images


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