Fire-extinguishing aerosol particles efficiently suppress the flame combustion but worsen evacuation conditions due to a decrease in the atmospheric transparency. After deposition, the particles create a corrosive environment. In addition, solid particles negatively affect the operation of devices moving parts and mechanisms. Removal of aerosol particles from the object is significantly difficult, especially from the closed cavities of devices, computers, etc.
Known studies contain sufficiently detailed information about the fire-extinguishing ability of various formulations of an aerosol-forming composition considering the conditions for their use. Less attention is paid to the transparency study of gas media with micron-sized particles both in our country and abroad.
At the same time, the study of fire extinguishing ability in relation to the transparency of the aerosol is extremely rare. Therefore, a study aimed at finding the mutual dependence of the aerosol-forming composition on the aerosol transparency is an urgent task.
The article proposes a calculated dependence for calculating the transparency index of a medium with an aerosol on the concentration and average diameter of the particles, while noting the convergence of the results of calculation and experiment. All the experimental data on the transparency of fire-extinguishing aerosol correlate with the known data on the dispersion of aerosol particles, which were obtained by the laser diffraction method. In this case, the dispersion assessment was carried out in a fairly simple way without use of the sophisticated equipment.
The medium transparency index and the fire-extinguishing ability of the aerosol are considered in interrelation. A series of experimental data was processed for the number of compounds of the aerosol-forming composition. As a result of data generalization, the dependence of the aerosol-forming compounds minimum extinguishing ability on the aerosol transparency in the range from zero to 100 % was obtained. It is shown that the use of aerosol filtration allows to increase the medium transparency to 50 % or more due to reducing the concentration of particles and increasing their size.
For all the compounds, the mass of the aerosol-forming composition increases, the combustion of which leads to an efficient fire extinguishing and more transparent aerosol. 
The application of the obtained results allows to reduce the volume of fire experiments in the development of new efficient and safe aerosol-forming compositions for fire extinguishing, as well as in the study of the transparency of media with aerosol.