Calculations of the ion-aerosol attachment coefficients are carried out for particles with radii between 0.001 and 4 μm in a bipolar ion environment by using the theory (Hoppel, 1977) that includes both image capture and three-body trapping of ions. These attachment coefficients are used to calculate the equilibrium charge distribution on aerosols. The results are compared to Fuchs' theory and to several recent measurements of the equilibrium charge distribution. The experimentally measured charge distributions agree quite well with theory. Recent measurements of aerosol size distributions made with the differential mobility size spectrometer in both continental and oceanic atmospheres are used together with the calculated attachment coefficients to study the sensitivity of the atmospheric ion concentration on the aerosol size distribution.