Today, one of the most important problems in the world is environmental and especially air pollution. Among the components of air pollution, especially heavy metals are of particular importance because they do not deteriorate and disappear easily in nature, can be toxic and carcinogenic to humans even at low concentrations, and bioaccumulate in living organisms. Therefore, it is extremely important to determine the heavy metal concentrations in the air. Barium (Ba), which has been largely neglected in studies on heavy metals, plays a key role in the production of many products in the industry. However, Ba is one of the most dangerous heavy metals and all barium compounds are toxic. This study was aimed to determine the accumulation of Ba concentration in some plants used extensively in Pakistan depending on traffic density. For this purpose, the variation of Ba concentrations in leaves and branches of Ficus bengalensis, Ziziphus mauritiana, Conocarpus erectus, and Azadrechta indica species depending on traffic density was determined. As a result of the study, it was determined that the most suitable species to be used for monitoring Ba concentration were Azadrechta indica leaves, and the most suitable organs were Azadrechta indica leaves.