The results of a study using epiphytic lichens as bioindicators, on teritory of three different urban areas in the Southern Serbia (Leskovac, Vlasotince, Lebane) are reported. The analysis of samples from 142 investigated points indicates presence of 53 lichens taxa. The aim of the study is to present the difference in air quality over a certain time interval. Using the Index of Atmospheric Purity- IAP values, it has been found that there are different air pollution zones: „normal“ zone, „struggle“ zone and „lichen desert“ zone. The comparison of the results obtained in 2002 and 2013 in Vlasotince indicates the presence of „normal“ zone in 2002 but, in 2013, the „normal zone“ area was completely replaced with the „struggle“ zone. In Leskovac, unlike the previous studies, a slightly narrowing “lichen desert" zone is noticed. In Lebane, there is a presence of all lichen zones.