Psychotropic substances in indoor environments

• Psychotropic substances affected indoor air at schools, homes and offices in Rome.
• The concentrations of psychotropic substances in the air changed with the time of year.
• The concentrations of psychotropic substances in the air changed with the type of site.
• Psychotropic substances were more abundant at target sites than at regional stations.
• The relative concentrations of cannabinoids depended on the indoor/outdoor location.

The presence of drugs in outdoor air has been established, but few investigations have been conducted indoors. This study focused on psychotropic substances (PSs) at three schools, four homes and one office in Rome, Italy. The indoor drug concentrations and the relationships with the outdoor atmosphere were investigated. The optimised monitoring procedure allowed for the determination of cocaine, cannabinoids and particulate fractions of nicotine and caffeine. In-field experiments were performed during the winter, spring and summer seasons. Psychotropic substances were observed in all indoor locations. The indoor concentrations often exceeded those recorded both outdoors at the same sites and at the atmospheric pollution control network stations, indicating that the drugs were released into the air at the inside sites or were more persistent. During winter, the relative concentrations of cannabinol, cannabidiol and tetrahydrocannabinol depended on site and indoor/outdoor location at the site.