The Use of UVC Irradiation to Sterilize Filtering Facepiece Masks Limiting Airborne Cross-Infection

Abstract

In addition to looking for effective drugs and a vaccine, which are necessary to save and protect human health, it is also important to limit, or at least to slow, the spread of coronavirus. One important element in this action is the use of individual protective devices such as filtering facepiece masks. Currently, masks that use a mechanical filter, such as a HEPA (High Efficiency Particulate Air) filter, are often used. In some countries that do not have a well-developed healthcare system or in exceptional situations, there is a real and pressing need to restore filters for reuse. This article presents technical details for a very simple device for sterilization, including of HEPA polymer filters. The results of biological and microscopic tests confirming the effectiveness of the sterilization performed in the device are presented. The compact and portable design of the device also allows its use to disinfect other small surfaces, for example a small fragment of a floor, table, or bed.

Ultraviolet-C as a Viable Reprocessing Method for Disposable Masks and Filtering Facepiece Respirators

“…Considering the studies in the SLR’s final database, 31 studies [ 1 , 6 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 49 , 50 , 52 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 63 , 64 , 65 , 66 , 85 ], representing 53.45% of the SLR database, attest to UV-C’s germicidal capability, as they find results of at least 3-log reduction using different biological indicators, conditions, and setups. These studies present results using UV-C as a single method of sterilization.…”

“…This information does not completely invalidate the “low-cost” idea, as they might prove to be cost-effective once the facility is looking for reprocessing masks and might already own such devices, and they may be idle. Lastly, some researchers created prototypes [ 41 , 53 ], or built their own UV cabinets [ 1 , 35 , 55 , 65 , 67 , 72 , 74 , 84 ]. These self-built UV cabinets are sometimes built from scratch using inexpensive raw materials like aluminum [ 1 , 65 ], or they adapted other containers [ 55 , 67 , 72 , 74 ], such as metallic tool storage, an old freezer box, or a reflecting box.…”

“…There are three common problems the UV-C sterilization process demonstrates: the possibility of thermal deformation, shadowing, and absorption effects [ 4 , 5 , 8 , 27 , 31 ]. As the first potential problem (changes in integrity) already discards reprocessed SUPPE, we opted to leave it on Table 1 column “Changes in integrity or fit.” From our SLR database, 30 studies (51.72%) assess it, of which 21 [ 33 , 35 , 37 , 40 , 44 , 48 , 49 , 51 , 53 , 61 , 62 , 64 , 65 , 67 , 70 , 71 , 73 , 80 , 81 , 82 , 87 ] observe no physical changes within different rounds of sterilization or extenuating conditions. On the other hand, nine studies [ 36 , 38 , 42 , 47 , 54 , 75 , 78 , 84 , 86 ] find that masks or FFRs degraded, or faced changes in airflow resistance [ 36 , 47 , 75 , 78 ], or reached minimum acceptability levels after some rounds of reprocessing [ 38 , 42 , 54 , 84 , 86 ].…”

Indoor air quality improvement in COVID-19 pandemic: Review

“…Three times higher radiation dose is required for the inactivation of bacterial spores than for polio and rotaviruses ( Chang et al, 1985 ). Kierat et al designed a sterilizer for deactivating the pathogens present on the face masks or any surface using the UV germicidal disinfection (UVGI) method ( Kierat et al, 2020 ).According to the chamber design, a mask can be sterilized on average within 15 min giving a radiation dose of 1 J/cm 2 three times without destroying the filtration properties. But non-transparent stiffening on the facemask was observed which inhibited the penetration of radiation to the next layers.…”

“… Widely used in hospitals for disinfecting surfaces. Directly damages DNA of pathogens, releases ozone gas, require pre-filters ( Chang et al, 1985 ; Kierat et al, 2020 ; Nakpan et al, 2019 ; Wielick et al, 2021 ) Ionization filter Use high dc voltage through corona discharge In industries and as portable purifiers in residential buildings Low energy costs, reduced formation of harmful emissions, potential health benefits, excessive electrostatic discharge charges objects, O 3 emissions ( Dong et al, 2019 ; Grabarczyk, 2001 ; Shiue et al, 2011 ) …”