Researchers at Stanford University have found that N95 masks can be effectively sterilised for reuse without affecting their filtration ability through low temperature heating in conventional kitchen ovens.
The findings could help alleviate a global shortage of the masks that are a crucial component of medical workers’ full personal protective equipment (PPE) against the coronavirus disease (Covid-19)
According to the research paper written by Dr Amy Price and Dr Larry Chu on behalf of the Stanford AIM Lab and Learnly Covid-19 Evidence Service, the N95 masks can be decontaminated repeatedly with no harm to their effectiveness by heating them at 70C in a regular kitchen oven for 30 minutes.
The same can be achieved using hot water vapour for 10 minutes, although this results in a marginal decline in filtration efficacy versus oven heating.
“It is unknown how wearing the same mask multiple times affects the fit of N95 masks,” the researchers acknowledged in their paper.
They cited the US National Institute for Occupational Safety and Health’s conclusions that “there is no way of determining the maximum possible number of safe reuses for anN95 respirator as a generic number to be applied in all cases”.
While other methods such as soaking in isopropyl alcohol decontaminate the masks, these significantly lower the remaining filtration ability of the masks after cleaning.
The rapid spread of Covid-19 to effectively all countries in the world in a matter of months has led to a severe global shortage of surgical masks and other forms of PPE.
Although reusing surgical masks is not recommended, the reality is that many frontline medical workers have had to reuse theirs repeatedly due to the acute scarcity while others have simply gone without them at great personal risk.
The shortage is also compounded by private demand for such masks.
Malaysia is also facing the same shortage, prompting the government to ban all exports of locally produced masks to alleviate the local scarcity.
Malaysia reported its 16th death from Covid-19 last night, with confirmed infections now at 1,624 cases.