Possibilities of retrieving a true value of the scattering coefficient and particle size distribution from data of a three-wavelength integrating nephelometer are analyzed. Two approaches to evaluation of the ratio of the true scattering coefficient to the measured one are suggested. Comparison of the aerosol micro-structure obtained from data of simultaneous measurements with an integrating nephelometer and with a nephelometer-polarimeter PhAN is carried out. The PhAN data are compared with measurements with a differential mobility analyzer.