University engineers have developed a prototype that disinfects nine healthcare respirators at one go, a handy tool in times of worldwide protective equipment shortages.

The Department of Electronic Systems Engineering at the University of Malta has designed and built a disinfecting unit that is relatively simple, low-cost and can be quickly built in large numbers.

The prototype can process over 400 specialised N95/FFP2 face respirators per day, and it will be donated to the Department of Infection Control at Mater Dei Hospital for evaluation in the coming days.

The World Health Organization has already warned that the dire lack of protective gear for health workers is proving a threat to attempts to beat the COVID-19 pandemic.

Up until Friday, over 50 doctors had died from COVID-19 and more than 6,400 health workers were infected in Italy. This could only boil down to shortage of personal protective equipment (PPE), inadequate PPE types or incorrect use and reuse of the same PPE, lecturer Marc Anthony Azzopardi said.

“In times of severe PPE shortages, healthcare workers are faced with a vexing dilemma: throw away precious face respirators after each shift and quickly run out of them or reuse them with the considerable risk that a contaminated respirator could itself become the cause of infection,” Azzopardi noted.

Azzopardi added that engineers were no strangers to the technology behind PPEs, including respirators.

After going through two decades of peer-reviewed research literature on disinfection methods for disposable PPEs, we selected a promising solution that appears very effective in destroying most pathogens without destroying the PPE itself in the process, he said.

Published research shows that with UVGI, a wide range of pathogens, including viruses, are very efficiently inactivated.

UVGI-treated respirators could thus be reused multiple times before they start visibly deteriorating. Until that happens, they seem to retain most of their air filtration effectiveness.

“The ultimate effectiveness of COVID-19 disinfection protocols for locally available respirator types is, of course, for the Infection Control Specialists to determine. However, by working together we can keep our health workers safe and well supplied with the equipment they need.”

The technicalities

The prototype uses short-wavelength ultraviolet germicidal irradiation (UVGI) and the concomitant generation of ozone gas, to substantially reduce the viral bioburden of up to nine disposable face respirators concurrently in a few minutes.

Once delivered, the equipment will include interlocks that will prevent accidental exposure of staff to UVGI which is associated with severe eye and skin damage.

Respirators are specialised face masks rated to international standards like NIOSH N95 and EN149 FFP2.

They are generally not designed for re-use, but the United States Food and Drug Administration has just issued an Emergency Use Authorisation for reprocessed face-piece respirators.