[en] During the time interval extending from April 29, 1986 to May 12,1986 the National Environmental Radioactivity Surveillance Network has monitored atmospheric aerosol radioactivity by performing six 3 hour samplings a day. The resulting filters were measured beta globally at the stations, then analyzed for gamma emitters at the Environmental Radioactivity Research Laboratory. This paper aims at analyzing the possibilities of identifying the pollutant sources starting from the air concentrations and taking into consideration the influence of the transport upon the contents of the contaminated air masses, by the evaluation of our data and the data in some reports published in other European countries. (author)