Vapour-sniffing drug detector tested at the US-Mexico border

The US Customs and Border Protection agency is testing technology that sniffs out illegal substances in the air, no contact required. The device could screen objects at the border within seconds to help combat the trafficking of drugs like fentanyl, which is driving the opioid crisis in the US.

Drugs and explosive chemicals are difficult to detect because they release relatively few molecules into the ambient air, which is already filled with other vapours. To solve this problem, Robert Ewing and his colleagues at the US Pacific Northwest National Laboratory (PNNL) in Washington state spent the past decade developing an extremely sensitive system called VaporID. It can accurately identify specific substances from 0.6 to 2.4 metres away at levels of 10 parts per quadrillion – comparable to finding a single coin in a stack of pennies 17 million times higher than Mount Everest.

The scientists achieved this by giving molecules from substances of interest more time to randomly bump into other molecules and produce a detectable chemical reaction. Most devices for identifying unknown substances give molecules only a few milliseconds to react, says Ewing. “We made the atmospheric flow tube, which provided 2 or 3 seconds of reaction time and gave three orders of magnitude increase in sensitivity.”

That technology is now incorporated into an 18-kilogram commercial device the size of a microwave oven. The miniaturised machine, developed by California-based company BaySpec, is less sensitive than the PNNL lab version, which weighs more than 100 kilograms and is the size of a small refrigerator. But it is still “more accurate and more sensitive than a canine”, says William Yang, CEO of BaySpec.

BaySpec and PNNL researchers tested the portable device at a Customs and Border Protection (CBP) facility in Nogales, Arizona, in October 2024. The team opened sample vials containing liquid or powder forms of seized drugs – including cocaine, heroin, fentanyl and methamphetamine – and held the open vials near the device inlet. In separate tests, researchers swiped the surface of seized pills and heated the swabs to generate vapor for detection. “Both methods produced strong, reliable results,” says Krisztian Torma at BaySpec.

The prototype is still undergoing evaluation and requires more scientific data review, says a CBP spokesperson.

Alex Krotulski at the Center for Forensic Science Research & Education, a non-profit organisation in Pennsylvania, says he remains “sceptical until the device has proven itself through research and rigorous evaluations, because we have seen far too many other devices in recent years that overpromised and underdelivered”.

There are already portable techniques, such as X-rays, for detecting hidden drugs, says Richard Crocombe, an independent consultant in Massachusetts. He calls the new tool “another valuable technique in the arsenal”, but cautions that “no one technique meets all needs”. For example, the CBP spokesperson notes that although it could potentially speed up drug testing in field labs, the new device would still require analysis by a trained chemist.

Such screening methods also risk raising false positives because “sometimes it feels like drug residue is pretty much everywhere”, says Joseph Palamar at New York University. Past research shows it has contaminated most US paper money, for example. “If it reacts as ‘positive’ for someone who has been near people using fentanyl and thus has minuscule traces on their clothes or shoes, then I worry about people who have nothing to do with drug trafficking being detained or penalised,” says Chelsea Shover at the University of California, Los Angeles.

Catching drugs before they enter the country is just part of a broader strategy necessary for curbing the opioid crisis, says Shover. However, solving this will also require robust public health agencies, access to healthcare and widespread treatment options, she says, which are currently being cut under the Trump administration. “To save lives, we want treatment – evidence-based, effective treatment – to be easier to access than illicit drugs,” says Shover.