Several small particles on a (wavy) leaf (Photo: Sadie Belica, Western Washington University Geology Department)
Larger particle Fe-oxide spheres produced by combustion, collected with a double-sided tape collector (Photo: Rachel Housen, Whatcom Middle School/Bellingham High School)
Measuring the level of magnetism of tree leaves could be a powerful tool to monitor the air quality of streets. A new study has shown that leaves along bus routes were up to ten times more magnetic than leaves on quieter streets. The magnetism comes from tiny particles of pollution, such as iron oxides from diesel exhaust, that float through the air and either stick to the leaves, or grow right into them.
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