Description:
Epiphytic lichens were used as bioindicators of air quality in the town of Montecatini Terme in central northern Italy. By means of 26 Index of Atmospheric Purity (LAP) relevés, a zone-map was drawn by automatic mapping programmes and the area was divided into 4 air quality zones. These zones were not concentric with respect to the city centre, suggesting that they are determined by air pollution and not by urban drought. The worst air quality occurred in urban areas with heavy motorized traffic and along a highway, while higher LAP values were found in areas free of traffic. These results are in agreement with data on the incidence of motorized traffic and air pollutants measured by recording gauges, which showed that SO2 levels were very low, NOx being the main pollutant. This allowed to conclude that in the area the main source of air pollution is from motorized traffic and that changes in lichen frequencies are largely determined by nitrogen oxides. Furthermore, the results underlined the fact that sulphur dioxide is no longer the main pollutant affecting lichen presence.