The Mossbauer spectroscopy was applied to study the structure of iron-
containing particles of atmospheric aerosols. From the temperature dep
endence of the Mossbauer spectra it was concluded that iron appears in
atmospheric aerosol mostly in the form of ultrafine, superparamagneti
c particles of Fe2O3. The analysis of the quadrupole splitting distrib
utions provides information on the differences of particle sizes in ae
rosols collected in different geographical locations.