The Environment Institute of the European Commission's Joint Research Centre has published a report of a study which monitored the amounts of benzene, toluene and xylene (BTX) in the atmosphere in Catania, Sicily. The project was carried out by the European Reference Laboratory of Air Pollution (ERLAP), based at the JRC, as part of the Multifund Operative Programme Sicily, which aims to assess the spatial distribution of background BTX exposure levels in Catania. The aim of measuring the levels of these volatile organic compounds in the atmosphere is to evaluate the risk resulting from exposure of the population to these contaminants, which represent major toxicological hazards - benzene is known to be carcinogenic. In addition, they also give indications of the emissions from traffic in the city. The report gives an account of the techniques used in the study, which was mainly based on passive samplers. These give a high spatial distribution and are also suitable for measuring background distribution. As no standard technique for passive sampling has yet been established, ERLAP suggests that the techniques used in this study may be considered as a useful contribution to on-going standardization work.