Behaviours of psychotropic substances in indoor and outdoor environments of Rome, Italy.

The intensive campaign conducted in March 2013 in Rome, Italy, at one coffee bar, one primary school and two homes revealed that in indoor environments, drugs can reach concentration levels exceeding orders of magnitude those recorded outdoors, even when the same substances are not consumed there. At homes, the gross average of cocaine reached 0.13 ng/m3 indoors and 0.09 ng/m3 outdoors (ratio~1.6); Δ9-tetrahydrocannabinol was 6.6 ng/m3 indoors and 1.1 ng/m3 outdoors (ratio~7); cannabidiol reached 0.30 and 0.07 ng/m3, respectively (ratio~6); and cannabinol 2.3 ng/m3 indoors and 0.7 ng/m3 outdoors (ratio~3). At the coffee bar, the average drug burdens were even higher, namely 0.33, 4.7, 14.3 and 2.5 ng/m3, respectively, for cocaine, cannabidiol, tetrahydrocannabinol and cannabinol. The school presented a special behaviour: the indoor/outdoor concentration ratios of cocaine, cannabidiol, tetrahydrocannabinol and cannabinol accounting for ~1.5, ~0, ~4 and ~0.5, in the order. Cocaine was more abundant on weekdays at all sites except one home indoors, whilst total cannabinoids prevailed on weekends at the other home and the school. Using the regional network stations as reference, all indoor locations except one were more contaminated by cocaine by a factor≥1.5, whilst cannabinoids were, aside from the school, up to 100 times higher.