Air quality nearby road traffic tunnel portals: BTEX monitoring.

A monitoring campaign of BTEX (benzene, toluene, ethylbenzene, o- m- and p-xylene) was carried out nearby two tunnel portals in the urban area of Naples with the aim to verify air quality in this kind of urban sites. Sampling was carried out using the active adsorption technique. Sampling time was 1 h. Ambient temperature and traffic flow measurements were carried out during each sampling operation. The results indicate that average benzene concentrations at both sites exceed the limit value of 10 microg/Nm3 established by the European Community (EC) (Dir. 2000/69). Concentration levels of other BTEX are relatively high as well. A correlation between BTEX concentration and two wheeler vehicle flow was observed.