Dwipayana, M.Y., Pradipta, G.A. and Hostiadi, D.P. 2026. Safety-Oriented Air Quality Index Classification for Imbalanced Data Using Optimized Boosting Models with Optuna and Oversampling . TIERS Information Technology Journal. 7, 1 (Jul. 2026), 17-31. DOI:https://doi.org/10.38043/tiers.v7i1.7558.