Reusable masks could slash pandemic waste

Since the Covid-19 pandemic began, doctors and other healthcare professionals have at times struggled to access enough face masks and other PPE as demand soars for protection capable of filtering SARS-CoV-2. Disposable N95 masks (approximately equivalent to FFF3 masks in Europe) have been in especially high demand, and in the early stages of the pandemic many hospitals reduced use by having healthcare workers wear a mask for a full day rather than switching between patients.

Some US hospitals used decontamination systems – which use hydrogen peroxide vapour or UV light – to sterilise masks for reuse, allowing one mask to be worn for several days.

All of those masks carry both financial and environmental costs; a new MIT study which analysed the costs of different mask use, has found that the impact of masks could be slashed by adopting reusable masks. Decontaminating regular N95 masks such that workers can wear them for more than one day drops costs and environmental waste by at least 75 per cent compared with using a new mask for every encounter with a patient, it found.

“Perhaps unsurprisingly, the approaches that incorporate reusable aspects stand to have not only the greatest cost savings, but also significant reduction in waste,” said Professor Giovanni Traverso: a mechanical engineering and gastroenterology expert.

The study also found that fully reusable silicone N95 masks could offer an even greater reduction in waste. Traverso and his colleagues are now working on developing such masks, which are not yet commercially available.

Last year, Traverso and his colleagues began developing a reusable N95 mask made of silicone rubber that contains an N95 filter which can be either discarded or sterilised after use. The masks are designed so they can be sterilised with heat or bleach and reused many times.

“Our vision was that if we had a reusable system, we could reduce the cost,” said Traverso. “The majority of disposable masks also have a significant environmental impact, and they take a very long time to degrade. During a pandemic, there’s a priority to protect people from the virus, and certainly that remains a priority, but for the longer term, we have to catch up and do the right thing, and strongly consider and minimise the potential negative impact on the environment.”

Traverso and his colleagues modelled the impacts of various mask-wearing scenarios: one N95 mask per patient, one per day, reuse of masks using UV decontamination, reuse using hydrogen peroxide sterilisation, and one surgical (not N95) mask per day. They also modelled the potential cost and waste generated by the reusable silicone mask they are in the process of developing, which could be used with either disposable or reusable N95 filters.

According to their analysis, if every health care worker in the United States used a new N95 mask for each patient they encountered during the first six months of the pandemic, the total number of masks required would be about 7.4bn, at a cost of $6.4bn (£4.7bn). This would lead to 84 million kg of waste: equivalent of more than 250 Boeing 747s.

Any of the reusable mask strategies would lead to a significant reduction in cost and in waste generated, the study confirmed. If each healthcare worker reused N95 masks decontaminated with UV light or hydrogen peroxide, costs would drop to $1.4bn to $1.7bn (£1bn to £1.3bn) over six months, and 13 million to 18 million kg of waste would result. Those numbers could potentially be reduced even further with a reusable, silicone N95 mask, especially if the filters were also reusable.

The researchers estimated that over six months, this type of mask could reduce costs to $18m and waste to 1.6 million kilograms.

“Masks are here to stay for the foreseeable future, so it’s critical that we incorporate sustainability into their use, as well as the use of other disposable personal protective equipment that contribute to medical waste,” said Dr Jacqueline Chu, lead author of the study.

Earlier this year, Welsh researchers warned that potentially dangerous chemical pollutants are released from disposable face masks when submerged in water. They called for urgent regulation and research regarding the pollutants.