In this note the particle surface transformations are examined, using the results obtained by electronic spectroscopy measurements. The tests concerned the preparation of condensation aerosols from metallic (Zn, Cd) vapours in N 2 flow (or N 2 and O 2) so as to obtain clean surfaces immediately brought in contact with the gas. On the surface, new sulphurated compounds and physically adsorbed gas layers were generated and revealed by degassing, using X-ray photoelectron spectroscopy (XPS-ESCA). The determination of the sulphur chemical state on the surface suggests a model of the particles composed of a metallic core and a layer, which depends on the particles' reactivity to the gas. These transformations can be responsible for behaviour in the atmosphere and irritant properties, and for dangerous effects for human health.