JENNIFER HEATHCOTE
Despite the ubiquitous presence in the air we breathe, little is known about the magnetic properties of urban air pollution. Only recently, as the need to regulate air pollution has risen, have researchers turned to magnetic analysis as possible means of quantifying urban pollution. In this study we analyze the air pollution produced by vehicles in a car tunnel near Zurich by looking at the difference between dust collected near the entrance and exit of the tunnel. We also compare the magnetic properties of the tunnel pollution with urban air pollution collected at several sites in and near Zurich and Rome. We conclude that vehicle emissions contain a high percentage of superparamagnetic particles (smaller than 30 nm), and in general it seems that urban air pollution is associated with higher percentages of superparamagnetic materials. We also confirm a tentative argument by Spassov et al (2004) that the distribution of switching fields for the tunnel pollutions is composed of two magnetic components (similar to the components Spassov et al found in their samples).