Can second-hand coke be as dangerous as second-hand smoke? This will be a new area for research as a new study has found that regions with high level of cocaine and marijuana use have higher concentrations of cocaine in the atmosphere.

The study also revealed a statistical relationships between cocaine levels and some cancers, and between cannabinoid levels and mental disorders. But Cecinato cautions about the meaning of these correlations, adding that the study could be a starting point for future research.

Analytical chemist Angelo Cecinato and colleagues at the Institute of Atmospheric Pollution Research in Rome who conducted a follow up study made by on the correlation between illicit drugs and the presence of airborne cocaine in Rome and some parts of Italy, also found out that there is a correlation between the level of airborne coke with the amount of drugs seized by police, and even a possible association with some types of crime, including robbery.

For their study, Cecinato and colleagues collected air samples, extracted the contaminants, and analyzed the results, checking for cocaine and cannabinoids in 20 spots in eight regions of Italy in winter and 39 sites in 14 regions in summer.

The team reported their findings in the Science of the Total Environment.

On the possible health risk of airborne coke to non-users, epidemiologist Wilson Compton of the National Institute on Drug Abuse, Bethesda, Maryland, said: "I wouldn't sound any alarm bells based on this one study. But 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."

"We're always looking for more accurate ways to gauge the amount of drug use in communities," he says, adding that better information could lead to improved treatment, education, and policing.