The approach to investigation of the properties of submicron atmospheric aerosol called "the method of active spectral nephelometry" is described in this paper. The technique and results of spectral polarimetric investigation of submicron aerosol with controlled influence on its properties are discussed in detail. Measurements were carried out by means of the instrumentation complex including a FAN nephelometer, the devices for humidification and heating of aerosol, and the block for cut-off of fine particles using a 4-stage diffusion battery. Solution of the inverse problem provided for obtaining the data on the size spectrum and the refractive index of aerosol particles. The estimates of the size dependence of hygroscopicity and volatility of aerosol particles are obtained. Measurements with the use of the diffusion cutter confirmed its calculated calibration function and the lower boundary of the retrieved size spectrum.