The researchers analyzed face masks worn by passengers and health workers, as well as an aircraft air filter, to examine the air in airplanes and hospitals. A study published today in the journal Microbiome shows that the air in both environments hosts harmless microbes primarily associated with human skin.
“We realized that we could use face masks as a cheap, easy air-sampling device for personal contact and casual contact,” Erica Hartman, the study’s lead author and an environmental microbiologist at Northwestern University, said in an emailed university statement. “We extracted DNA from those masks and examined the types of bacteria found there. Not surprisingly, the bacteria were the types we typically associate with indoor air. Indoor air looks a lot like indoor air, which also looks a lot like human skin.”
used face mask
In total, Hartmann and his colleagues identified 407 microbial species, such as common skin bacteria and environmental microbes. They also found very few disease-causing pathogens, possibly without evidence of active infection. Not surprisingly, the study took place in January 2022, at the heart of the COVID pandemic. Hartman received a grant to search for pathogens in airplane cabin filters, but he realized that investigating high-efficiency particulate air (HEPA) filters could be complicated.
“At the time, there was a serious concern about COVID transmission on planes,” said Hartman, an expert on the indoor microbiome. Because HEPA filters are so efficient, “we thought this would be a great way to capture everything in the air. But these filters are not like the filters we have in our cars or homes.” They are very expensive, and “to remove them, crews have to take the airplanes out of service for maintenance. This obviously costs an incredible amount of money, and it was eye-opening.”
That’s when the team thought of a much cheaper and simpler device that also passively captures germs: face masks. As such, the team collected face masks from volunteers, who wore them on domestic and international flights. For comparison, volunteers also sent face masks with them on flights, but they were never worn. To investigate the differences between indoor environments, the researchers chose another busy, closed space with heavily filtered air: hospitals. And so he collected face masks from hospital workers, which they wore during their work shifts.
microbe dna
The researchers analyzed DNA from the exterior of each mask, which revealed that the air in both environments contained a diverse but mostly harmless mix of microbes, with little evidence of any one being pathogenic. The samples taken from both locations included most of the common bacteria associated with humans, particularly in indoor air and from our skin. What’s more, the microbes in both environments were very similar, although the amount of each microbe was slightly different. Ultimately, the similarities show that the germs in both airplane and hospital air come from the people themselves – specifically, from their skin, not from their disease – and not from particular environments.
The researchers also found some antibiotic resistance genes associated with major classes of antibiotics. This doesn’t mean that dangerous germs are floating around, but it does indicate the extent to which antibiotic resistance has spread.
Furthermore, “for this study, we only looked at what’s in the air,” Hartman concluded. “Hand hygiene is an effective way to prevent diseases spread from surfaces. We were interested in what people are exposed to through the air, even if they are washing their hands.”
This study should be good news for anyone looking to fly during the upcoming holidays.
<a href