Abstract: Respiratory protectiion masks have been widely used during the COVID-19 pandemic. Due to the shortage of supplies, medical researchers have tried to disinfect and reuse the masks, including sterilization by ionizing radiation. Based on the gamma irradiation device of Shanghai Jinpengyuan Irradiation Technology Co. Ltd., the KN95 and KN100 respiratory protection masks are irradiated to study the influence of different doses and dose rates on the filtration efficiency of the masks. The iron plate shielding and the shielding of the irradiated items of the production line are used to generate two sets of radiation field with dose rates(1.9 kGy/h,3.66 kGy/h). The absorbed doses of the masks are measured with a silver dichromate dosimeter, Harwell Amber 3042 dosimeter, and UV-2450 ultraviolet spectrophotometer. Both masks conform to the standard GB 2626—2019, so the recommended method in the GB is used to measure the filtration efficiency on particulate matter. The measurement data were processed, and the influence of the radiation dose on the electrostatic collection efficiency of the mask was estimated. The results show that the filtration efficiency of the two masks decreases rapidly with the increase of the absorbed dose, regardless of the high or low dose rate. In the end, the filtration efficiencies of the KN95 and KN100 masks are maintained at 68.2%-72.9% and at 89.7%-93.7%, respectively. Ionizing radiation eliminates the static electricity on the protection masks. The electrostatic collection efficiency of single mask fiber of KN95 accounts for 80.1% of the total collection efficiency, and for KN100 it accounts for 72.5%.

Key words: KN95, KN100, electrostatic elimination with ionizing radiation, electrostatic collection efficiency