Assessment of the impact of the vehicular traffic on BTEX concentration in ring roads in urban areas of Bari (Italy).

A BTEX monitoring campaign, consisting of two weekly periods, was carried out in Bari, south-eastern Italy, in order to evaluate the impact of the vehicular traffic on the air quality at the main access roads of the city. Twenty-one sampling sites were selected: the pollution produced by the traffic in the vicinity of all exits from the ring road and some access roads to the city, those with higher traffic density, were monitored. Contemporarily the main meteorological parameters (ambient temperature, wind, atmospheric pressure and natural radioactivity) were investigated. It was found that in the same traffic conditions, barriers, buildings and local meteorological conditions can have important effects on the atmospheric dispersion of pollutants. This situation is more critical in downtown where narrow roads and high buildings avoid an efficient dispersion producing higher levels of BTEX. High spatial resolution monitoring allowed both detecting the most critical areas of the city with high precision and obtaining information on the mean level of pollution, meaning air quality standard of the city. The same concentration pattern and the correlation among BTEX levels in all sites confirmed the presence of a single source, the vehicular traffic, having a strong impact on air quality.