Adverse health effects of occupational exposures to metal-containing airborne particles have long been recognized. To reduce
the adverse effects caused by metal-containing particles, it is important to make clear where they are from. SPM has been
applied to the study of the sources of chromium, manganese, nickel and zinc in aerosol particles PM10. Micro-PIXE spectra of single particles were treated as fingerprints since each particle was characterized by its micro-PIXE
spectrum. The sources of the metal-containing particles were identified using the fingerprints of single particles. The study
shows that the major sources of the four kinds of metals in the air are metallurgic emission, vehicle exhaust, coal combustion
and soil dust.