Collection, measurement, and analysis of airborne magnetic particulates from pollution in the environment (invited)

Magnetic particulates in the environment, collected from surfaces and directly from the atmosphere, are reported. A significant percentage of magnetic material in many air-borne samples consists of spherical magnetite from coal-burning utilities and from iron/steel manufacturing with particle diameters 2–10 μm which correspond to average coercive fields of ∼100 Oe and remanence to saturation ratios of ∼0.1. The amount of air-borne magnetic material that settles to the ground varies inversely with distance from its source.