Levels of cocaine and other psychoactive substances in atmospheric particulate matter (PM) were determined in urban environments representing distinct social behaviours with regard to drug abuse: night-life, university and residential areas. Three cities (with population >1 million and <0.3 million inhabitants) were selected. Mean daily levels of drugs in PM were 11–336 pg/m 3 for cocaine, 23–34 pg/m 3 for cannabinoids, and 5–90 pg/m 3 for heroin. The highest levels were recorded on weekends, with factors with respect to weekdays of 1–3 for cocaine, 1–2 for cannabinoids and 1.1–1.7 for heroin. Higher levels were detected in the night-life areas, pointing towards consumption and trafficking as major emission sources, and possibly ruling out drug manufacture. The similarities in temporal trends at all sites suggested a city-scale transport of psychoactive substances. Correlations were detected between cocaine and amphetamine consumption ( r 2 = 0.98), and between heroin and cannabinoids ( r 2>0.82). ► Cocaine, heroin, cannabis and related illicit drugs are found in detectable amounts in urban air. ► Illicit drug consumption and small-scale trafficking are the major emission sources. ► Illicit drugs remain in atmospheric particles and are transported across cities during at least 5 days. ► Levels of illicit drugs increase from residential to night-life areas, and maximise on weekends. ► Correlations between illicit drugs were detected, suggesting differences in consumer groups. The presence of illicit drugs in atmospheric particles can be used to track illicit drug abuse.