Dose Reduction Effects of Face Masks against Radon Progeny Inhalation (1):

The present study aimed at estimating dose reduction effects of face masks against radon progeny inhalation. As the first step, changes in aerosol number concentrations before and after passing through masks were investigated. Four types of masks were used for the experiment: non-woven masks, N-95 masks, urethane masks, and gauze masks. Reduction rates of aerosol number concentrations for four particle size ranges were measured at two experimental conditions. First, each mask was attached to a tube with a diameter of 55 mm and air was sucked through the mask with a defined flow rate to estimate filtration efficiency. Secondly, a mannequin head wearing each mask was prepared and air was sucked through the mannequin nose and mouth. All four types of the masks showed reduction effects on the aerosol number concentrations. The reduction rates were different among the mask types and also among particle size ranges. In addition, the experiment at the two different conditions indicated that the reduction effect depended on the adhesiveness of the mask to the face as well as the mask types. The aerosol reduction rates for different particle size ranges are expected to be generally useful for inhalation protection against aerosols.