Since the start of the Covid-19 pandemic last year, face masks and other personal protective equipment have become essential for healthcare workers. N95 disposable masks have been in particular demand to help prevent the spread of SARS-CoV-2, the virus that causes Covid-19.
All of these masks have financial and environmental costs. It is estimated that the Covid-19 pandemic generates up to 7,200 tonnes of medical waste every day, much of which is disposable masks. And even if the pandemic slows in some parts of the world, healthcare workers should continue to wear masks most of the time.
That toll could be significantly reduced by adopting reusable masks, according to a new study from MIT which has calculated the financial and environmental cost of several mask use scenarios. Decontaminating regular N95 masks so that healthcare workers can wear them for longer than a day reduces costs and environmental waste by at least 75%, compared to using a new mask for each encounter with a patient.
“Not surprisingly, approaches that incorporate reusable aspects should not only generate the greatest cost savings, but also a significant reduction in waste,” says Giovanni Traverso, assistant professor of mechanical engineering at MIT, gastroenterologist at Brigham and Women’s Hospital, and the study’s lead author.
The study also found that fully reusable N95 silicone masks could offer an even greater reduction in waste. Traverso and his colleagues are currently working on the development of such masks, which are not yet commercially available.
Jacqueline Chu, a physician at Massachusetts General Hospital, is the lead author of the study, which appears in the British Medical Journal Open.
Reduce and reuse
At the start of the Covid-19 pandemic, N95 masks were scarce. In many hospitals, healthcare workers were required to wear a mask for a full day, instead of changing for each patient they saw. Later, some hospitals, including MGH and Brigham and Women’s Hospital in Boston, began using decontamination systems that used hydrogen peroxide vapor to sterilize masks. This allows a mask to be worn for a few days.
Last year, Traverso and his colleagues began to develop a reusable N95 mask made of silicone rubber and containing an N95 filter that can be discarded or sterilized after use. The masks are designed in such a way that they can be sterilized with heat or bleach and reused multiple times.
“Our vision was that if we had a reusable system, we could reduce costs,” says Traverso. “The majority of disposable masks also have a significant environmental impact, and they take a very long time to degrade. In a time of a pandemic, there is a priority to protect people from the virus, and it certainly remains a priority, but in the longer term, we need to catch up and do the right thing, and seriously consider and minimize the risk. potential negative impact on the environment. “
Throughout the pandemic, hospitals in the United States have used different mask strategies, depending on the availability of N95 masks and access to decontamination systems. The MIT team decided to model the impacts of several different scenarios, which encompassed use patterns before and during the pandemic, including: one N95 mask per patient encounter; one N95 mask per day; reuse of N95 masks by ultraviolet decontamination; reuse of N95 masks by sterilization with hydrogen peroxide; and one surgical mask per day.
They also modeled the potential cost and waste generated by the reusable silicone mask they are currently developing, which could be used with either disposable or reusable N95 filters.
According to their analysis, if every healthcare worker in the United States used a new N95 mask for every patient encountered in the first six months of the pandemic, the total number of masks required would be around 7.4 billion, for one. cost of $ 6.4 billion. This would result in 84 million kilograms of waste (the equivalent of 252 Boeing 747s).
They also found that all reusable mask strategies would lead to a significant reduction in costs and waste generated. If every healthcare worker could reuse N95 masks that have been decontaminated with hydrogen peroxide or ultraviolet light, costs would drop to $ 1.4 billion to $ 1.7 billion over six months, and 13 to 18 million kilograms of waste would result (equivalent to 56,747s).
These numbers could potentially be further reduced with a reusable N95 silicone mask, especially if the filters were reusable as well. The researchers estimated that over six months, this type of mask could cut costs to $ 18 million and waste to 1.6 million kilograms (about 2.5747s).
“The masks are here to stay for the foreseeable future, so it is essential that we incorporate sustainability into their use, as well as the use of other disposable personal protective equipment that contributes to medical waste,” said Chu.
The data used by the researchers for this study was collected during the first six months of the pandemic in the United States (end of March 2020 to end of September 2020). Their calculations are based on the total number of healthcare workers in the United States, the number of Covid-19 patients at the time, and the length of hospital stay per patient, among other factors. Their calculations do not include any data on the use of masks by the general public.
“We’ve focused here on healthcare workers, so it’s probably an under-representation of the total cost and environmental burden,” notes Traverso.
While vaccination has helped reduce the spread of Covid-19, Traverso believes healthcare workers will likely continue to wear masks for the foreseeable future, to protect themselves not only from Covid-19 but other respiratory illnesses as well. such as the flu.
He and others started a company called Teal Bio which is now working to refine and further test their reusable silicone mask and develop methods to mass-produce it. They plan to seek regulatory approval for the mask later this year. While cost and environmental impact are important factors to consider, the effectiveness of masks should also be a priority, says Traverso.
“At the end of the day, we want the systems to protect us, so it’s important to know whether or not the decontamination system compromises the filtering ability,” he says. “No matter what you use, you want to make sure that you are using something that is going to protect you and others.”
Massachusetts Institute of Technology