Every living thing spreads an invisible signature across its landscape, whether it’s a badger ambling through the grass, an oak growing in the forest, or an eagle soaring overhead. Fur, feathers, skin cells, spores, pollen—all of it is loaded with genetic information that floats away into a data-rich atmospheric soup. Scientists call this information environmental DNA, or eDNA, and it is so potent that in January 2022 researchers announced they’d been able to identify the species in two zoos just by sampling eDNA in the surrounding air.
James Allerton, an air quality scientist at the UK’s National Physical Laboratory, read about that experiment and had one of those wait just a minute ideas. The laboratory operates a number of air quality monitoring networks, including the UK’s heavy metals network. At these monitoring stations, air passes through filters, which are then analyzed to measure levels of toxic metals. “We had not sat at NPL thinking: I wonder if there’s recoverable DNA material on these filters?” Allerton recalls. Yet the idea was too intriguing to ignore. “When you read a report about people who’ve successfully managed to capture animal DNA out of the air—and there we are, working in particulate measurements—then you have the light-bulb moment.”
In particular, Allerton and fellow NPL air quality scientist Andrew Brown wondered if the lab’s instruments had inadvertently been accumulating a bounty of eDNA that would track local biodiversity. “Some of them in the UK were established as far back as the 1960s and 1970s,” says Brown of the monitoring stations. “So they’re effectively out there taking samples in exactly the same way every single day, every single week, every single month of every single year for a very long time.”
The two reached out to the biologists behind the zoo study—Joanne Littlefair of Queen Mary University of London and Elizabeth Clare of York University Toronto—to join forces. Today in the journal Current Biology, they’re announcing their groundbreaking findings: Between an air quality monitoring station in Scotland and another in London, they were able to detect over 180 kinds of organisms via eDNA. That includes a menagerie of animals, like deer, hedgehogs, badgers, and newts; plants that include trees, grasses, wheat, and other crops; and 34 species of birds, including songbirds, pigeons, and little owls.
Their study suggests that atmospheric scientists all over the world have been accidentally collecting genetic data that could give biologists unprecedented insight into changing ecosystems. This would be a vast and incredibly valuable cache of information. “Even weekly samples at thousands and thousands of sites is more data on biodiversity than we’ve ever seen,” says Clare. “In biodiversity science, we consider annual surveys to be high-resolution data. So the idea that there are weekly surveys being carried out like this—that are basically automated—is something that I don’t think we’ve ever considered before.”
In fact, Clare says, air quality scientists hadn’t considered it, either. “We’ve had a lot of these conversations with scientists the last couple of weeks and people who run these networks,” says Clare. “When we say: ‘Did you realize it does this too?’ They all have a moment of sort of shocked look on their face. And then they go, ‘Oh, but of course it must.’ It really seems obvious once you’re told about it, but it isn’t obvious, because the people operating them aren’t biologists.”
Airborne eDNA could turn into a powerful tool for preserving species, says Craig Leisher, director of monitoring and evaluation at the Nature Conservancy, who wasn’t involved in the new research. For example, if the DNA of an invasive species begins to waft into a protected area, atmospheric instruments could alert conservationists to the threat. Such monitors would be particularly powerful on islands, which are highly vulnerable to invasive species, like rats: If an instrument gets a whiff of rodent DNA, it could immediately prompt conservationists to spring into action.
