Walking into a hospital or onto a plane, masked faces dot the space — many wary of catching something, from the common cold to COVID-19.
But a recent study by the Hartmann Lab in the journal “Microbiome” concluded that the ambient air in these environments is mostly composed of harmless microbes. Supported by a grant from the Walder Foundation, the lab examined the microbiomes found on face masks and detected 407 distinct microbial species — of which few were potentially pathogenic species.
“The original idea was to see the longevity, or the survival time of viruses, such as COVID,” first author and postdoctoral scholar Oliyad Jeilu said. “But we decided that studying viruses in that scenario was a little bit challenging.”
Instead, the researchers broadened their focus to airborne microbes more generally.
The study has been Jeilu’s main focus during his time at Northwestern. After the pandemic, everyone was worrying about traveling on airplanes, Jeilu said, and the team was interested in what the pathogen landscape looked like in high human-traffic areas — such as travel or healthcare settings.
At first, the lab wanted to gather samples from air filters in airplanes.
However, procuring those proved more difficult than expected, according to lab director McCormick Prof. Erica Hartmann. Accessing a filter requires taking the plane out of service and moving it into maintenance, and the filters cost thousands of dollars, Hartmann said, which made access “prohibitively difficult and expensive.”
So the team pivoted to analyze face masks, which they asked volunteers to wear on domestic and international flights, and hospital workers to wear on shifts.
The results showed that the microbes present on masks from both environments were similar, suggesting that people were the main source of airborne microbes — not the specific settings the samples were collected from.
Hartmann credits researcher Charlie Catlett with the initial idea for the study. When Catlett stepped away from the role and Jeilu joined the lab, he came up with strategies for trying to extract as much material from the masks as possible, Hartmann said. This included working with enrichment culture, a technique that amplifies small amounts of bacteria until there’s enough to analyze.
“It combines the gold standard of microbiology, the methods that have been in use for over 100 years, with the cutting edge DNA sequencing, which is what we ultimately used for detection,” Hartmann told The Daily.
A key takeaway from this study, Hartmann explained, is that they now know this method of collecting samples from masks is a viable approach to “environmental surveillance.”
Thinking outside of the box regarding how to improve access to samples is critical, fifth-year civil and environmental engineering Ph.D. candidate and study co-author Anahid Moghadam said.
“It would be really beneficial to the community and to countries to be able to apply this kind of surveillance system so we can actually catch stuff before it impacts people,” Moghadam said.
The study also found a small number of antibiotic-resistant microbes on these masks. However, Hartmann said, what they found is not necessarily actionable, describing it as “an interesting observation” that would require more epidemiology information.
Hartmann added that this study was an example of how people might think about getting “a little extra mileage” out of what would otherwise be considered disposable, such as face masks.
“I’d like to encourage people to also not necessarily think of waste as a dead end, but consider what you might be able to get from that — consider what else we might be able to do that’s really interesting,” Hartmann said.
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