The Environmental Toll of Disposable Masks – And How To Reduce It

A new study calculates the waste generated by using N95 and suggests possible ways to reduce it.

Since the Covid-19 pandemic started last year, face masks and other personal protective equipment have become essential for health professionals. Disposable N95 masks are in high demand to help prevent the spread of SARS-CoV-2, the virus that causes Covid-19.

All these masks entail both financial and environmental costs. The Covid-19 pandemic is estimated to generate up to 7,200 tons of medical waste every day, much of it disposable masks. And even as the pandemic slows in some parts of the world, health workers are expected to continue wearing masks most of the time.

That toll could be drastically reduced by using reusable masks, according to a new study from MIT that calculated the financial and environmental costs of various mask-use scenarios. Disinfecting regular N95 masks so health professionals can wear them for more than a day cuts costs and environmental waste by at least 75 percent, compared to using a new mask for each patient encounter.

The Covid-19 pandemic is estimated to generate up to 7,200 tons of medical waste every day, much of it disposable masks. Credit: Stock Photo

“It is perhaps not surprising that the approaches that incorporate reusable aspects not only provide the greatest cost savings, but also a significant reduction in waste,” said Giovanni Traverso, an assistant professor of MIT mechanics, a gastroenterologist at Brigham and Women’s Hospital, and the study’s senior author.

The study also found that fully reusable silicone N95 masks could provide an even greater reduction in waste. Traverso and his colleagues are now 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.

Reduce and reuse

In the early stages of the Covid-19 pandemic, N95 masks were in short supply. In many hospitals, health workers had to wear one mask for an entire day, instead of switching to a new mask for every patient they saw. Later, some hospitals, including MGH and Brigham and Women’s Hospital in Boston, began using decontamination systems that use hydrogen peroxide vapor to sterilize masks. This allows one mask to be worn for several days.

Last year, Traverso and his colleagues began developing 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 so that 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 costs,” says Traverso. “Most disposable masks also have a significant impact on the environment and take a very long time to degrade. During a pandemic, protecting people from the virus is a priority, and it certainly remains a priority, but for the longer term, we need to catch up and do the right thing, strongly considering and minimizing the potential negative impact on the environment. ”

During the pandemic, hospitals in the United States have used a variety of mask strategies, based on the availability of N95 masks and access to decontamination systems. The MIT team decided to model the effects of several scenarios, including patterns of use 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 with hydrogen peroxide sterilization; and one surgical mask per day.

They also modeled the potential costs and waste generated by the reusable silicone mask they are now developing, which can be used with disposable or reusable N95 filters.

According to their analysis, if every health professional in the United States used a new N95 mask for every patient they encountered during the first six months of the pandemic, the total number of masks needed would be about 7.4 billion, at a cost of $6.4 billion. This would result in 84 million kilograms of waste (the equivalent of 252 Boeing 747 aircraft).

They also found that each of the reusable mask strategies would significantly reduce costs and waste generated. If every health professional could reuse N95 masks disinfected with hydrogen peroxide or ultraviolet light, the cost would drop to $1.4 billion to $1.7 billion in six months and create 13 million to 18 million kilograms of waste. (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 estimate that this type of mask could reduce costs to $831 million and waste to 1.6 million kilograms (about five 747s) over six months.

“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 single-use PPE that contribute to medical waste,” Chu says.

Environmental impact

The data the researchers used for this study was collected during the first six months of the pandemic in the United States (late March 2020 to late September 2020). Their calculations are based, among other things, on the total number of healthcare workers in the United States, the number of Covid-19 patients at that time and the length of hospital stay per patient. Their calculations do not include data on mask use by the general public.

“Our focus here was on health professionals, so it’s probably underrepresented in total costs and environmental impact,” notes Traverso.

While vaccination has helped reduce the spread of Covid-19, Traverso believes health professionals will likely continue to wear masks for the foreseeable future, to protect not only against Covid-19 but also other respiratory illnesses, such as the flu .

He and others founded a company called Teal Bio that is now working to further refine and test their reusable silicone mask and develop methods for mass production. 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 the masks should also be a priority, Traverso says.

“Ultimately, we want the systems to protect us, so it’s important to know if the decontamination system is compromising filtering capacity or not,” he says. “Whatever you’re using, you want to make sure you’re using something that will protect you and others.”

Reference: “Thinking green: Modeling respirator reuse strategies to reduce costs and waste” by Jacqueline Chu, Omkar Ghenand, Joy Collins, James Byrne, Adam Wentworth, Peter R. Chai, Farah Dadabhoy, Chin Hur and Giovanni Traverso, July 18, 2021, BMJ Open.
DOI: 10.1136/bmjopen-2021-048687

The research was funded by the MIT Undergraduate Research Opportunities Program, the National Institutes of Health and MIT’s Department of Mechanical Engineering. Other authors of the article are Omkar Ghenand, an MIT student; Joy Collins, senior clinical research coordinator at Brigham and Women’s Hospital and former MIT technical officer; James Byrne, radiation oncologist at Brigham and Women’s Hospital and research affiliate at MIT’s Koch Institute for Integrative Cancer Research; Adam Wentworth, research engineer at Brigham and Women’s Hospital and research affiliate at the Koch Institute; Peter Chai, an emergency physician at Brigham and Women’s Hospital; Farah Dadabhoy, a research affiliate of MIT; and Chin Hur, professor of medicine and epidemiology at Columbia University.