The Regional Air Quality Deterministic Prediction System (RAQDPS) carries out physics and chemistry calculations to arrive at deterministic predictions of chemical species concentration of interest to air quality. Chemical constituents include O3, SO2, NO and NO2, gases as well as fine particulate matter PM2.5 (2.5 micrometers in diameter or less) and coarse particulate matter PM10 (10 micrometers in diameter or less). Predictions are available from the current day out to 72 hours into the future. Geographical coverage is the North American domain. Data is available at a horizontal resolution of 10 km. While the system encompasses 84 vertical levels, data is available only for the surface level. Predictions are performed twice a day.