We propose a sampling strategy, using individual dosimetry to measure the daily inhaled quantity of PAHs in urban air. The method was applied to monitor 56 subjects living in an Italian town (Pavia; 80 000 inhabitants) and the Environmental Reference Concentration (E.R.C.) of six PAHs (classified as 'possible' carcinogenic agents for humans) was determined. The individual environmental samplings took place in two different seasons (winter and summer), for persons living in four different urban areas with different traffic density. Subjects were selected using a specific questionnaire designed to collect information on indoor and indoor+outdoor exposure times. The mean +/- S.D. value of Benzo[a]pyrene [BaP] was 0.37 +/- 0.15 ng m-3 in winter and 0.12 +/- 0.07 ng m-3 in summer. Assuming 18 m3 as the daily inhaled quantity the estimate of the BaP inhaled quantity was 6.66 ng/day in winter and 2.16 ng/day in summer.