IoT-enabled air quality prediction using ensemble machine learning: a case study in San Salvador, El Salvador - Josue Ramirez-Ramirez; Daniel Amaya-Cruz; Griselda Zepeda-Navarro; Bayron Carpio-Villaran; Miguel Alfaro-Vides; Yakdiel Rodriguez-Gallo; Omar Otoniel Flores-Cortez; Carlos Osmín Pocasangre Jiménez; Werner David Meléndez (Air Quality, Atmosphere & Health, 2026)