2000–2020 Monthly Air Quality Index (AQI) Dataset of China

This dataset provides monthly gridded Air Quality Index (AQI) data covering the entire territory of China from 2000 to 2020, with a spatial resolution of 1 km. The data were generated to support research on the associations between long-term/seasonal air pollution exposure and cardiovascular disease (CVD) risk in Chinese older adults (aged ≥65 years), as part of a study using the China Health and Retirement Longitudinal Study (CHARLS, 2011–2020) cohort. It captures fine-scale spatial and temporal variations in air quality across China, enabling precise linking of environmental exposure to individual health outcomes. China’s national standard (GB 3095–2018) as the maximum index among six criteria pollutants (PM₂.₅, PM₁₀, SO₂, CO, NO₂, O₃). Eighteen predictors were integrated to ensure accuracy, including meteorological variables (e.g., 2-m air temperature, 10-m wind speed from the China Meteorological Forcing Dataset), vegetation metrics (Normalized Difference Vegetation Index [NDVI], Net Primary Productivity [NPP]), anthropogenic factors (downscaled GDP, population density, Human Footprint Index), and soil properties (pH, soil organic carbon from China’s High-Resolution National Soil Information Grid). Four tree-based ensemble algorithms (Random Forest [RF], Gradient Boosting Machine [GBM], CatBoost, XGBoost) were compared, with the RF model selected as optimal (test set: R² = 0.83, Root Mean Square Error [RMSE] = 10.25, Mean Absolute Error [MAE] = 9.03) after validation via 10-fold geographic stratified cross-validation and 100 bootstrap iterations; Recursive Feature Elimination (RFE) further refined 14 core predictors to minimize overfitting. The dataset is provided as NCnet files (252 total, one per month) covering China (80°E–135°E, 15°N–53°N).