Hourly air quality, meteorology and traffic data for 13 stations in Istanbul (2017–2025)

Hourly PM2.5, PM10, NO2 and O3 concentrations at 13 Istanbul Metropolitan Municipality (IMM) monitoring stations (2017–2025, gap-filled, with imputation flags), ERA5 meteorology at the nearest grid point, and hourly station-level traffic density (2020–2025). All timestamps are local time (UTC+3). Data accompanying the manuscript “Benchmarking N-HiTS and Gradient Boosting for Short-Term Multi-Pollutant Forecasting Across Istanbul’s Air Quality Network”. See README.md for details.