Radiation is an effective and established tool to sterilise personal protective equipment that is in high demand during the current pandemic. However, it should not be used for espiratory face masks as it weakens their filters, the International Atomic Energy Agency (IAEA) said.
While radiation is not recommended to sanitise certain types masks, the IAEA encourages member states to continue to irradiate other PPE for sterilisation prior to their use, including surgical masks and gloves.
At the request of several countries, the IAEA reviewed findings from five institutions that tested the use of ionising radiation – gamma and electron beams – to sterilise used respiratory masks, including N95 and FFP2 models commonly worn by medical personnel.
As the numbers of Covid-19 infections increase, shortages in PPE for staff on the frontline continue to pose a problem in many countries.
“Many governments are looking to expand the availability of PPE by sterilising them with chemicals, UV light or radiation,” said Celina Horak, a radiation processing specialist at the IAEA. “Face masks are of particular interest, as they are indispensable for hospital staff but also used among the general population.”
Respiratory face masks such as the N95 and FFP2 masks, contain filters that block small external airborne particles and droplets. They differ from surgical masks, which mainly protect others against the wearer’s own respiratory emissions.
However, tests carried out by institutes in France, Israel, South Korea, Poland, and the USA showed that the level of radiation required to sterilise respiratory face masks decreased their filtering performance.
“The masks showed no significant changes in fit or measurable structural changes when exposed to the 24kGy dose of radiation needed to kill viruses and bacteria, but filtering capacity was significantly compromised,” said Byungnam Kim, head of the irradiation facilities at the Advanced Radiation Technology Institute of the Korea Atomic Energy Research Institute (KAERI), which carried out tests using electron beams.
Similar results were obtained by the ARC-Nucleart Laboratory in France.
“In FFP2 masks, which include an electrostatic filter, results clearly showed that gamma radiation degrades the filtering performance, even at lower doses,” said Laurent Cortella, senior researcher at the Laboratory.
Radiation sterilisation has been used since the late 1950s to eliminate microorganisms, such as bacteria, viruses, fungi and spores, from medical equipment. Currently, almost 50% of healthcare products, including gloves, syringes and single use protective clothing, are sterilised using gamma rays, electron-beams or X-rays prior to their use.
The use of radiation has, in some countries, been extended to disinfect alternative types of community protection items. In Brazil, the Nuclear and Energy Research Institute (IPEN) is using radiation to sterilise textile masks produced by local seamstresses. IPEN is treating 50,000 of these masks for distribution during the pandemic.
Photo: Radiation is an effective and established tool to sterilise PPE, except for respiratory face masks as it weakens their filters, the International Atomic Energy Agency (IAEA) has said