Before researchers at Battelle Memorial Institute could use their Critical Care Decontamination System on much-needed N95 masks, they had to understand how the system would affect plastics.
Five of the six main components of the standard N95 mask made by 3M use some type of plastic. Its straps are made from thermoplastic elastomers, the nose foam is polyurethane and the filter is polypropylene fiber. The mask's shell and cover both are made of polyester.
In a May 12 interview with Plastics News, Battelle principal research scientist William Richter said that the CCDS, which uses concentrated, vapor phase hydrogen peroxide, had been used on some plastic medical devices, but hadn't been used in a large scale on N95 masks. The masks have been in short supply worldwide because of the COVID-19 crisis.
"We had used this type of technology for decontamination, but we had to put the [N95] masks through multiple iterations of testing," said Richter, who's been with Columbus, Ohio-based Battelle since 2002.
The masks are exposed at a validated concentration level to decontaminate biological contaminants, including SARS-CoV-2. The testing also determined how many times each N95 mask could be used without degrading its performance.
Richter said that testing showed that the mask's PP fiber filter could be decontaminated 50 times without affecting its efficiency. The TPE head strap, however, started to show loss of elasticity after only 30 decontaminations. As a result, Battelle recommends that each mask be decontaminated only 20 times.
The Battelle CCDS is based on a Food and Drug Administration study completed after a 2016 contagion. Richter said that earlier work gave the institute an advantage when testing the N95 masks this year.
"The key was that initial research so that we didn't need a year of R&D," he said. "We were able to go from lab-scale to a deployable unit in a week."
Officials said that Battelle is conducting research to validate whether other equipment, including surgical masks and ventilator components, can be decontaminated using this process. Face shields and Chinese-made KN95 masks, which are similar to N95s, also will be tested, Richter said. Silicone also is a possible replacement material for the head straps, he added.
In the decontamination process, health care systems collect worn N95 masks each day. The masks then are labeled with a barcoded serial number for tracking chain of custody throughout the process. This procedure ensures that the hospital system receives its own respirators back.
Battelle CCDS operations are in place at 25 U.S. sites with plans to add 19 more. Each site can clean up to 80,000 masks per day.
Battelle was founded in 1929 and ranks as the world's largest nonprofit research and development organization, employing more than 22,000 at more than 60 locations.