[en] An automatic three-cascade impactor recording air α-radioactivity distributed on aerosol particles was proposed. Aerosol particles in the impactor were distributed in the ranges rsub(0.5) > 0.36 μm, 0.16μm < rsub(0.5) < 0.36 μm and rsub(0.5) < 0.16 μm. Where rsub(0.5) is an effective radius of the particles deposited with 50% probability on the impactor plates

[en] The results of the experimental investigations on quantitative evaluation of the ²¹⁸Po and ²¹⁴Bi washout efficiency by fog in an aerosol chamber are presented. The radioactivity has been measured by means of α-spectrometric method. Comparison of eXperimental and calculated data is made. The ²¹⁸Po and ²¹⁴Bi washout efficiency ratio is found to be dependent mainly on the aerosol concentration. The change of ²¹⁸Po concentration imitates the process of coagulation of free atoms of light ions, and that of ²¹⁴Bi - of aerosol particles by fog droplets