PAH measurements in Belgium: Experience and concentration levels

Results are presented of PAH measurements in Flanders and Brussels at diffe rent locations. Low flow sampling on filters is used to collect particulate phase PAH which are extracted with dichloromethane by ultrasonic or micro- Soxhlet extraction and analysed by means of HPLC with fluorescence detectio n or GC-MS in SIM-mode. The highest concentrations were found in winter per iods exceeding those in the summer by a factor of 2.5 to 4.5 depending on t he location. PAH concentration levels in Brussels are slightly higher than in the Flanders locations. On the absence of local occasional sources, annu al averages calculated from 90 samples are within 10 % of the values calcul ated from all samples.