This is an audio long read from nature.

In this episode, the air is full of DNA.

Here's what scientists are using it for.

Written by Ashling Irwin and read by me, Benjamin Thompson.

Ryan Kelly is in awe of what floats invisibly in the air. It is completely mind-blowing,

says Kelly, who studies environmental DNA, or E-DNA at the University of Washington in Seattle.

We are absolutely surrounded by information in the form of DNA and RNA at all times.

Scientists have long pulled DNA from water and soil, but they have only just started to see

the air as a source of genetic information. Over the past decade or so, researchers have

been learning how to measure airborne DNA, study its abundance, and use it to

put together a picture of an ecosystem's inhabitants and health. Airborne DNA is being used to monitor

individual species and being trialed as a way to detect invasive species or attacks with biological weapons.

It is also being tested as a way to judge the success of conservation efforts.

The technique promises to link, quote, the whole of biodiversity, the whole world together,

with a single assay that's really rapid and that can even be done in the field and

analysed in the cloud, says David Duffy, a researcher who specialises in wildlife disease genomics

at the University of Florida in St Augustine. But there is still a lot to pin down, such as how

fast DNA decays in the air and how far it travels.

Some genetic material pulled from the air comes from humans, and several scientists are concerned

that when using the technique for conservation research, it could inadvertently reveal people's

ethnicity or whether a person has a genetic disorder and even be used

to identify individuals. Scratch your head and you'll release DNA-rich cellular material into the air.

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