How Clean Is Airplane Air, Really?

Just in time for the busy holiday travel season, researchers report a question that will cross many people’s minds as they pile onto crowded planes: How clean is plane air?

To find out, Erica Hartmann, an associate professor in the department of civil and environmental engineering at Northwestern University, and her colleagues tested the masks worn by flight passengers to record the types of insects trapped by these products. The team also looked at the air circulating in hospitals, another public place where germs commonly spread, and tested the masks worn by hospital staff.

The team collected 53 masks in sterile bags and cut the outer layers to analyze only microbes circulating in the air and not in people’s respiratory tract, then extracted and analyzed the DNA. To ensure they detected all the microbial DNA present, they also used an amplification process called PCR to enrich what was present on the masks.

Overall, they report in the newspaper Microbiotathey detected 407 microbial species from both the plane and the hospital, with similar populations of insects in each. The vast majority of them come from the skin and are harmless, says Hartmann. “This is not surprising, because many microbes in buildings and in the air around us reflect us,” she says. “Many surfaces we touch tend to contain skin-associated insects, because we transmit insects every time we touch something. We shed microbes everywhere we go – my colleagues and I call this a microbial aura.”

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The kits the team used to extract genetic material from microbes were designed to collect DNA, meaning the researchers captured mostly bacteria, not viruses, many of which have RNA as their genetic basis (like COVID-19 and the flu). While people might be more concerned about the amount of virus floating around in a confined space like an airplane cabin, Hartmann says viruses are likely to make up a smaller proportion of microbes in the air than bacteria, because people shed bacteria through their skin in greater quantities than they release virus particles.

She notes that viruses tend to be very dependent on the right habitat to grow, and once outside the body and away from the cells they can infect, they can become slightly less virulent – ​​although there are many examples of viruses surviving on surfaces, and studies show that it only takes a small amount of virus to infect someone and make them sick.