"Perhaps unsurprisingly, the approaches that incorporate reusable aspects stand to have not only the greatest cost savings, but also significant reduction in waste," says Giovanni Traverso, an MIT assistant professor of mechanical engineering, a gastroenterologist at Brigham and Women's Hospital, and the senior author of the study.
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.
Jacqueline Chu, a physician at Massachusetts General Hospital, is the lead author of the study, which appears in the British Medical Journal Open.
Last year, Traverso and his colleagues began developing a reusable N95 mask that is made of silicone rubber and contains an N95 filter that can be either discarded or sterilized after use. The masks are designed so they can be sterilized with heat or bleach and reused many times.
"Our vision was that if we had a reusable system, we could reduce the cost," Traverso says. "The majority of disposable masks also have a significant environmental impact, and they take a very long time to degrade. During a pandemic, there is 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 minimize the potential negative impact on the environment."
Throughout the pandemic, hospitals in the United States have been using different mask strategies, based on availability of N95 masks and access to decontamination systems. The MIT team decided to model the impacts of several different scenarios, which encompassed usage patterns before and during the pandemic, including: one N95 mask per patient encounter; one N95 mask per day; reuse of N95 masks using ultraviolet decontamination; reuse of N95 masks using hydrogen peroxide sterilization; and one surgical mask per day.
They also modeled the potential cost and waste generated by the reusable silicone mask that they are now 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 7.4 billion, at a cost of $6.4 billion. This would lead to 84 million kilograms of waste (the equivalent of 252 Boeing 747 airplanes).
They also found that any of the reusable mask strategies would lead to a significant reduction in cost and in waste generated. If each health care worker were able to reuse N95 masks that were decontaminated with hydrogen peroxide or ultraviolet light, costs would drop to $1.4 billion to $1.7 billion over six months, and 13 million to 18 million kilograms of waste would result (the equivalent of 39 to 56 747s).
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 $18 million and waste to 1.6 million kilograms (about 2.5 747s).
"Masks are here to stay for the foreseeable future, so it is critical that we incorporate sustainability into their use, as well as the use of other disposable personal protective equipment that contribute to medical waste," Chu says.
MEDICA-tradefair.com; Source: Massachusetts Institute of Technology