Researchers say airborne traces of illegal drugs could pose a health risk for people as the air pollution does.

Scientists at the Institute of Atmospheric Pollution Research in Rome found traces of cocaine and cannabis in the air around dozens of sites in Italy.

Researchers also discovered statistical correlations between cocaine levels and certain types of cancer – and between cannabis levels and mental disorders.

The project’s leader, Angelo Cecinato, was cautious about drawing firm conclusions from his study, but epidemiologist Wilson Compton of the National Institute on Drug Abuse, Bethesda, Maryland, told Science Now:

“The researchers did find this link, and it’s worth further exploration.

“Second-hand cigarette smoke wasn’t considered a health threat either, until comparatively recently.”

Angelo Cecinato and his team tested air quality in 59 sites in Italy across various regions in the summer and winter months, screening it for cocaine and cannabinoids, the active ingredient in marijuana.

As well as the links with health problems, researchers found higher airborne concentrations of the drugs in areas where police had made big seizures, where higher than average numbers of people requested treatment and with cocaine levels and certain types of crime.

The results left the team wondering if air-testing for drugs might be a cheaper and more efficient way for authorities to target drug abuse.

Wilson Compton added: “We’re always looking for more accurate ways to gauge the amount of drug use in communities.”