João Matias is an epidemiologist, graduated from the London School of Hygiene and Tropical Medicine (LSHTM). In 2004, he joined the European Monitoring Centre for Drugs and Drug Addiction as a scientific agent in the Prevalence, data management and content coordination Unit. He is now scientific analyst on drug use, responsible for the key epidemiological indicator ‚Prevalence and patterns of drug use‘, including amongst other drug use in nightlife settings and the European Web Survey on Drugs. He has also worked at the United Nations Office on Drugs and Crime (UNODC) as an analyst on drug markets.