This repository contains the complete supplementary dataset for the work "A Decade of Air Pollution Sustainability Progress across OECD Countries: A Stability-Benchmarked, Two-Level Hierarchical Longitudinal MCDM Framework" It providing all data, calculation steps, formulas, and analysis outputs necessary for replicating the study's methods and results. The dataset covers 38 OECD countries across 9 SDG indicators spanning 2015–2024, structured into five integrated files: 1. Annual_DM_Normalizations.xlsx Annual decision matrices (raw data) and five normalization schemes (N1–N5: Sum, Vector, Min-Max, Maximum, and Composite) for each year. This file constitutes Phase 1 of the TOPSIS benchmarking framework, establishing the standardized input matrices for subsequent weighting and evaluation. 2. Annual_Entropy_Weightings.xlsx Annual Entropy weighting results derived from each normalization method (N1–N5), presenting objective indicator weights based on information entropy theory. Includes Level 1 (indicator-level), Level 2 (domain-level: ET, EE, HSCV), and Global (combined) weight structures for 2015–2024. 3. Annual_CRITIC_Weightings.xlsx Annual CRITIC weighting results using the Criteria Importance Through Intercriteria Correlation method, applied across all five normalization schemes. Provides contrast-intensity and correlation-based indicator weights at three hierarchical levels for each year. 4. Annual_Integrated_E_C_Weightings.xlsx Integrated Entropy-CRITIC weighting results combining 5 Entropy normalization schemes with 5 CRITIC normalization schemes, yielding 25 hybrid weighting combinations (E-N1_C-N1 through E-N5_C-N5). Includes Coefficient of Variation (CV) tests for weight stability validation across methods and years, supporting robustness assessment of the integrated approach. 5. TOPSIS_Results.xlsx Complete multi-criteria evaluation outputs, including two-level evaluation rankings, performance clustering, periodic (long-term) performance indices, rank stability and temporal dynamics analyses (2015–2024) across four dimensions (ET, EE, HSCV, APS), and inter-dimensional correlation analysis. Data Scope: 38 OECD countries | 9 SDG indicators (I1–I9) | 3 domains (Energy Transition, Environmental Exposure, Health System Capacity & Population Vulnerability) | 10 years (2015–2024) Methodological Coverage: Decision matrix construction, five normalization techniques, Entropy and CRITIC objective weighting, 25 integrated hybrid weighting schemes, CV stability testing, two-level TOPSIS evaluation, rank clustering, temporal stability analysis, and inter-dimensional correlation analysis.