WHEN in Rome, you get a little hit of cocaine with every breath.

A study of psychotropic drug levels in ambient air from eight Italian cities found background levels of cocaine, cannabinoids – the active ingredients in marijuana – nicotine and caffeine in every urban centre.

Turin had the highest concentrations of cocaine, says Angelo Cecinato at the Institute of Atmospheric Pollution Research in Rome. Meanwhile, Bologna and Florence had some of the highest cannabinoid levels, which Cecinato attributes to the large student populations in the two cities. The drug concentrations are much too low to have an effect, though (Environmental Pollution, doi.org/jhk).