Objectives: Exposure to particulate matter 2.5 (PM_2.5) remains a critical public health issue in China. Understanding its spatial distribution and associated mortality burden is crucial for developing effective preventive strategies. Material and Methods: This study analyzed PM_2.5 distribution and estimated premature mortality from chronic obstructive pulmonary disease (COPD) and lung cancer attributable to PM_2.5. The analysis covered different districts and 3 age groups in Lanzhou City, using the global exposure mortality model (GEMM). Results: From 2014 to 2023, PM_2.5 concentrations were significantly reduced city-wide. However, the number of PM_2.5-attributable premature deaths did not decline substantially. In some districts, these deaths even increased against a backdrop of rising overall mortality. The majority of premature deaths occurred in people aged ≥65 years. Lowering PM_2.5 concentrations remains important for controlling mortality from both diseases. However, the trends were not entirely consistent, indicating a complex relationship between PM_2.5 and mortality. Conclusions: Particulate matter 2.5 continues to have a substantial impact on health. Sustained efforts in air quality improvement and targeted health interventions for the elderly population are necessary. Int J Occup Med Environ Health. 2026;39(1)