"Roadside surveys conducted in 13 countries across Europe, in which blood or oral fluid samples from 50 000 drivers were analysed, revealed that alcohol was present in 3.48 %, illicit drugs in 1.90 %, medicines in 1.36 %, combinations of drugs or medicines in 0.39 % and alcohol combined with drugs or medicines in 0.37 %. However, there were large differences among the mean values in the regions of northern, eastern, southern and western Europe. Although the absolute numbers were quite low, the prevalence of alcohol, cocaine, cannabis and combined substance use was higher in southern Europe, and to some extent in western Europe, than in the other two regions, whereas medicinal opioids and ‘z-drugs’, such as zopiclone and zolpidem, were detected more in northern Europe."


European Monitoring Centre for Drugs and Drug Addiction, "Driving Under the Influence of Drugs, Alcohol and Medicines in Europe — findings from the DRUID project" (Luxembourg: Publications Office of the European Union, 2012), doi: 10.2810/74023, p. 6.