There are many researches that find the relationship and the effect between lichen and NO2 which released from traffic. Van Dobben and Ter Braak (1998) and Gombert et al. (2003) found the effect of NO2 on lichen distribution. Van Dobben and Ter Braak (1998) found that NO2 predominantly released by traffic, was the second-most important factor explaining the distribution of lichen species apart from SO2. As same as Gombert et al. (2003) studied the influence of urban roads on the nitrogen concentration of a nitrophytic lichen, Physcia adscendens and an acidiphytic one, Hypogymnia physodes in the Grenoble area (France). They found that lichen and nitrogen concentrations were analyzed and mapped for the whole urban area. It was indicated that roads influenced the nitrogen concentrations of P. adscendens, but not those of H. physodes. Significant positive correlations were found between this traffic index and the total nitrogen concentration of P. adscendens.