Real-Time Long Horizon Air Quality Forecasting via Group-Relative Policy Optimization. - Inha Kang; Eunki Kim; Wonjeong Ryu; Jaeyo Shin; Seungjun Yu; Yoon-Hee Kang; Seongeun Jeong; Eunhye Kim; Soontae Kim; Hyunjung Shim (CoRR, 2025)