KN95 and N95 respirators retain filtration efficiency after decontamination

The Coronavirus Disease 2019 (COVID-19) pandemic has caused a major impact on human health and society. The main transmission between humans is aerosols and droplets. When an infected person coughs, sneezes, or speaks, the virus is excreted and dissolved droplets or aerosols that can remain and travel in the air.



N95 respirators have been used to protect wearers against such viral aerosols and droplets. They can filter at least 95% of particles. The study investigates the filtration performance of both N95 and KN95 respirators. Charge density is related to electrostatic filtration but has not yet been investigated during decontamination. The fiber integrities of N95 and KN95 respirators before and after dry-heat decontamination were also investigated.


After various decontamination methods, the fiber integrity of N95 and KN95 respirators is found maintained without any deformations. The filter layers of N95 respirators were 8-fold thicker and had 2-fold higher dipole charge density than that of KN95 respirators. Emergency Use Authorization (EUA)-approved KN95 respirators showed filtration efficiencies as high as N95 respirators.


It is interesting to found that although there was a significant drop in the dipole charge in both respirators during the decontamination, there was no remarkable decrease in the filtration efficiencies. Therefore, it can be concluded that a loss of electrostatic charge does not directly correlate to the decreased of either respirator.   


(CITATION: KN95 and N95 Respirators Retain Filtration Efficiency despite a Loss of Dipole Charge during Decontamination, Wonjun Yin, Diyi Cheng, Shiv H. Patel, Rui Kou, Yang Shirley Meng and Jesse V. Jokerst)