Magnetic Particles Unintentionally Emitted from Anthropogenic Sources: Iron and Steel Plants

Magnetic particles suspended in the atmosphere have attracted public attention due to their adverse health impacts. However, the origin of these magnetic particles has not been addressed. This study first reports the magnetic properties and chemical characteristics of emitted dusts from various anthropogenic sources. On the basis of the combination of magnetic parameter measurements and PM2.5 emission inventories, the iron and steel industry contributes >80% of the total magnetic particle emission among the studied emission source categories. In contrast, the magnetic particles emitted from other sectors make up a significantly smaller portion. Magnetite is the dominant magnetic contributor, as suggested by X-ray diffraction, Mossbauer spectra, and X-ray absorption studies. Morphological studies further indicate that nanoscale magnetite contained in steel plants derived particles is consistent with that found in human tissues. Our results suggest that applying a priority control strategy in the iron and steel industry can decrease the unintended emission of magnetic particles.