Air quality stations have been quietly picking up eDNA for decades

Air quality monitoring stations around the world could be hiding a treasure trove of ecological data, according to a team of UK and Canadian researchers.

The stations are picking up fragments of environmental DNA (eDNA) from plants, animals, insects, and fungi in their air filters.

According to the researchers, this means they can be used to monitor biodiversity at a global scale.

They’ve published their findings in Current Biology.

“Almost every country has some kind of air pollution monitoring system or network, either government owned or private, and in many cases both,” says first author Dr Joanne Littlefair, a researcher at Queen Mary University of London, UK.

“This could solve a global problem of how to measure biodiversity at a massive scale.”

The researchers collaborated with the UK’s National Physical Laboratory (NPL), which operates the country’s national air sampling grids.

“Air is filtered as part of the air quality networks used in routine monitoring for particulates and pollutants,” explains Littlefair.

The researchers set up an air quality station in London, where they collected nine samples.

They also examined eight historical samples that had been collected in Scotland as part of routine air sampling. The Scottish filters had been stored at room temperature for eight months.

In the samples from both locations, they found eDNA from more than 180 different taxa, representing plants, fungi, insects, mammals, birds, fish, and amphibians.

These samples ranged from popular garden plants to more elusive wild species like little owls and smooth newts.

“We were very excited to see the breadth of taxa which were recovered,” says Littlefair.

“Personally, I found the amount of different types of birds really surprising and pleasing. In the future, we’d love to place mobile samplers in nature reserves; for example, which are important for bird migration.”

This means that air quality samplers are storing information that could be used to judge biodiversity at a global scale, and possibly look at how the ecology of an area has changed over time.

“If networks of air samplers around the world are all collecting similar material – just as a part of their regular functioning – it’s an incredible resource,” says co-author Dr Andrew Brown, who operates NPL’s network.

Littlefair says that NPL’s current practice is to store their filters at room temperature, but freezing them would yield more data.

“One of the things we are trying to achieve with this publication is to halt the discarding of these filters and to ask laboratories to store them in a way that could preserve DNA,” she says.

The findings come as other scientists have raised concerns about the risks (and possible benefits) of finding human DNA in eDNA sampling.

“DNA from all mammals ends up in the air, so human DNA will too,” says Littlefair.

“However, we actually don’t want this kind of DNA in our samples because it overwhelms the signal from other mammals which we are interested in for biodiversity monitoring.

“In the lab we take steps to reduce this by using “blocking probes” which reduce the amount of human DNA recovered.”