Air pollution is one of the most important problems being currently encountered by human beings throughout the world. It is exasperated in big cities by improper growth of industrial activities, fossil fuel consumption, and also high population growth. Atmospheric pollution is a serious, continuous, and comprehensive threat for the health of organisms and the environment. In addition to environmental consequences and the problems for the health of human and other organisms, air pollution causes social and economic problems. Suspended dust particles are the major air pollutants in arid and semiarid areas. Plants can be good indicators for evaluating air pollution since most plants have high ability to absorb and accumulate heavy metals by their leaves. That is why plants could be used as bioindicator to measure atmospheric pollution. Shiraz city has been facing high air pollution in recent years which may negatively influence its environment and the health of its high population. Therefore, it is necessary to examine the level of atmospheric pollution in this important city. The objectives of this study were: (1) to evaluate the level of atmospheric pollution, (2) to examine the ability of pine needles and plane tree and cedar leaves as bioindicators for air pollution estimation, and (3) to compare the level of heavy metals accumulation and the magnetic susceptibility of the leaves of the above-mentioned trees in high and low traffic urban areas. Ten urban sites including 5 sites in each areas having either high or low vehicle traffic were chosen. Leaf samples from the 3 trees were collected at the end of July, August, September, and October 2017. Samples were thoroughly washed with water in the lab and then dried in oven. The dust particles associated with the plant leaf samples were also separated and dried. Magnetic susceptibility of the dried leaf samples was determined using a Bartington MS2B instrument. Also, the concentrations of Fe, Cu, Co, Ni, Zn, and Mn and those of Pb and Cd in the leaf samples were measured using an atomic absorption spectrometer after dry and wet digestion, respectively. The results indicated that Fe, Mn, Ni, Co, and Pb showed an accumulating trend with time in plane tree leaves and Fe, Mn, Co, and Pb showed the same trend in pine needles and cedar leaves. This indicates that heavy metals loaded particles have been trapped and conserved by the plant leaves. The concentration of almost all the heavy metals had an increasing trend with time. The highest magnetic susceptibility and also concentration of Fe, Co, Pb, and Ni belonged to the cedar leaves indicating the great ability of cedar leaves i absorbing heavy metals from atmospheric pollution. This could be attributed to the morphology of cedar leaves as well as their somehow sticky secreted materials. Plane tree leaves had only significantly higher concentration of Zn than those of the other two tree species. Plane tree leaves appear to absorb less atmospheric particles as compared to pine needles and cedar leaves. The amount of magnetic susceptibility in pine needles and cedar leaves is significantly higher in densely trafficked areas than that in low traffic sites. However, no significant difference was found in the magnetic susceptibility of plane tree leaves in areas with different traffic density. There were positive correlations between the concentrations of Fe, Cu, Zn, and Pb and magnetic susceptibility in the cedar leaves likely indicating their identical anthropologic sources. This may also show that cedar leaves could be used as a good bioindicator and also a reliable biomagnetic index to determine highly polluted areas. Besides, the concentration of Co, Mn, and Pb in plane tree leaves, that of Pb, Zn, and Cu in pine needles, and that of Pb, Zn, Fe, and Cu were significantly higher in high traffic areas than the low traffic ones. The concentration of Pb and Zn in the atmospheric dust particles associated with the leaves of all the three tree species was higher in high traffic areas than the low traffic urban sites. The concentration of Zn and Pb in both leaf samples and the atmospheric dust particles associated with them was highly influenced by the traffic level. Traffic and other human activities seem to play a major role in causing atmospheric pollution. The simple and low cost approach of measuring biomagnetic properties of the tree leaves could be used to monitor air pollution in in urban areas. Among the 3 trees, the use of cedar leaves appears to provide more reliable results when used as a biomagnetic index or as a biomonitor, in general. Keywords : Atmospheric contamination, biomagnetic evaluation, bioindicator, dust, shiraz.