Around the world, near cities, highways and industrial sites, monitoring stations are silently sucking up air to provide government agencies and others with information about chemicals that pollute the atmosphere.
Now a team of scientists in Canada and Britain has found that those same devices are providing a second, previously unrecognized function: collecting fragments of DNA that are literally blowing in the wind and can be used to identify wildlife.
The ready-made genetic sample is an asset that should not be squandered, the scientists say, particularly when improved biological monitoring is seen as a central requirement for countries trying to meet international goals for conserving species and habitats.
“We want to alert the community of researchers to what exists and to stop the destruction of what might be invaluable material,” said Elizabeth Clare, a biologist and assistant professor at York University in Toronto.
To demonstrate their point, Dr. Clare and Joanne Littlefair at Queen Mary University in London, England, analyzed DNA extracted from air pollution monitoring stations at two sites in England and Scotland. They identified more than 180 species of vertebrates, insects, plants and fungi based on fragments of DNA that had accumulated in the devices.
“In the first few samples we looked at … the data was better than any biodiversity technique I have ever seen,” Dr. Clare said.
When multiplied by the thousands of sites that comprise pollution-monitoring networks around the globe, the results suggest there is a vast trove of ecological information to be mined.
“This is game-changing for our approach to biodiversity monitoring on land,” the scientists wrote in a description of the work, published Monday in the journal Current Biology.
Ecological regions that are best covered by air monitoring stations can be found in North America, Europe and parts of Asia as part of routine pollution sampling, the scientists point out. But there are also some stations operating in the Global South. Currently, most jurisdictions do not archive air quality samples once they have been analyzed. Dr. Clare said the study was published quickly in order to encourage the saving and freezing of samples to benefit biodiversity monitoring efforts worldwide.
She and Dr. Littlefair previously studied airborne DNA that they collected in zoos using special samplers of their own design, but Dr. Clare said the new study came about by chance.
It began when James Allerton, a researcher at Britain’s National Physical Laboratory who specializes in the measurement of airborne particles, read a report last year from the Natural History Museum of London about the zoo-based research that Dr. Clare and Dr. Littlefair had done. The story got him wondering whether the air samplers his laboratory employed might also be collecting DNA as a byproduct.
“It seemed like a no-brainer to contact them, and so I did,” Dr. Allerton said.
Together with Andrew Brown, an air-quality chemist at the laboratory, Dr. Allerton teamed up with the biologists to set up a pilot study of residue from monitoring devices. The group conducted much of the study using one device based at the laboratory, which is located about 15 kilometres west of central London. There they were able to vary the sampling time from one hour to one day to one week to see which would provide the best results. They also used a filter that did not limit particle size, to maximize the possibility of taking in more DNA.
The group then looked at routine samples gathered from an air-quality measuring station in a more rural area, in Scotland, which also sat in the sampler for 28 days before being collected. Dr. Clare said both sites yielded good data on wildlife around the monitoring stations, including 34 species of birds, which suggests that stations may also offer a way to track the movements of migratory species.
The work is the latest to show how DNA persists in the environment and can now be assessed with increasing ease thanks to a revolution in genetic technologies. A study published last month noted that this includes human DNA, raising concerns about privacy and surveillance.
Dr. Clare said human DNA, including from researchers, is common in environmental samples and, in her work, viewed as a contaminant that needs to be subtracted as part of any analysis. She added that the kind of monitoring she and her colleagues proposed in their study is aimed at identifying species, not individuals.
David Castle, a bioethicist and researcher in residence with Canada’s Office of the Chief Science Advisor, who was not involved in the study, said the results show the promise of environmental DNA gathered from air-quality networks for countries that need better tools to understand what species they host and what they need to protect. Given the potential value of the samples, he said, governments should be looking now at their air-sampling activities to determine if they are gathering useful information on wildlife species and taking steps to make sure the data is not lost.
“Air capture of environmental DNA has enormous potential for biodiversity monitoring and will need to complement other techniques,” he said. “To me, the most worrying issue is not moving quickly enough.”