Housen Magpart (1 of 2) (IMAGE) Geological Society of America Caption Tree leaves along bus routes in Bellingham, WA, were found to be up to 10 times more magnetic than leaves on quieter streets. Magnetism comes from tiny particles of pollution -- such as iron oxides from diesel exhaust -- that float through the air and either stick to leaves or grow right into them. This photo of a larger particle, taken with a scanning electron microscope, shows one of the Fe-oxide spheres produced by combustion, and collected with a double-sided tape collector. Credit Rachel Housen, Whatcom Middle School/Bellingham High School. Usage Restrictions non-commercial and educational only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.