This study estimated lead (Pb) and cadmium (Cd) concentrations in tree-ring wood of Aleppo pine (Pinus halepensis Mill.) and evaluated its efficiency as a bioindicator of atmospheric heavy metal pollution. Wood and soil samples were collected from seven trees at sites with varying exposure levels along Al-Bayda City's main streets and from reference sites outside the city. The study covered two decades (2000–2010 and 2011–2021) for temporal comparison. Samples were analyzed using Atomic Absorption Spectroscopy, and the Bioaccumulation Factor (BAF) was calculated. Exploratory statistical analysis was conducted, and the Wilcoxon Signed-Rank Test was used to compare decades within the same trees and to compare BAF-Pb with BAF-Cd. All analyses were performed using SPSS version 23. Results showed a clear upward trend in Pb concentrations, increasing from 0.071 mg/kg in the first decade to 0.075 mg/kg in the second, indicating continued Pb accumulation. This was supported by a high mean BAF for Pb (2.57), demonstrating efficient Pb uptake from soil. In contrast, Cd concentrations declined slightly in the second decade (from 0.026 to 0.019 mg/kg), with a low BAF (1.04), indicating limited Cd accumulation. A pronounced spatial variation was observed, with Pb values ranging from 0.012 mg/kg at less polluted sites to 0.12 mg/kg at sites most affected by human activities—a tenfold difference reflecting the influence of traffic density, industrial activities, and proximity to pollution sources. Cd concentrations ranged from 0.009 to 0.041 mg/kg, showing relatively low levels with spatial variation among sites. The study concludes that tree-ring analysis, particularly of Aleppo pine, is an effective and reliable tool for long-term environmental monitoring of heavy elements, provided that qualitative variation among elements and local environmental factors are considered. It recommends enhancing the use of trees, especially Aleppo pine, as bioindicators in national and local monitoring systems, due to their accuracy, ease of sampling, lower cost, and ability to document temporal changes, thus contributing to a historical database for tracking pollution trends........................ Keywords: ............Aleppo pine, tree rings, lead, cadmium, bioindicator, bioaccumulation factor, air pollution, Libya.