The work presented below deals with the modernization of the method for testing the protection factor of a protective mask against sodium chloride (NaCl) aerosols. The aim of the work is to show the possibility of modernizing the method which, unlike the existing method with a flame photometer (FP), uses a laser photometer (LP). The reason for this is the dependence of the accuracy of the method on the operation of the FP, which uses the combustion of hydrogen gas for its operation. Problems occur with changes in the hydrogen-oxygen concentration required for flame maintenance and FP operation, as well as the quality of hydrogen, which cannot be influenced. The main challenge in establishing the method is to find the ideal characteristics of the laser light source that enables the detection of aerosol NaCl particles and all other particles, especially carbon particles, whose number and concentration vary during the test, should be negligible, so filters for masking the photometer are not necessary for the operation of the new method. The function of the new method must meet the measurement of NaCl mass concentrations up to 15mg/m3 , and the measurement sensitivity is 5ng/m3 . The certified device FIELD MAX II was used to adjust and detect the wavelengths of the laser photometer as well as to determine the required power of the laser light source.