The free-to-use Aerosol Alerts service, developed by a team at the Norwegian Meteorological Institute, uses forecasts provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System to provide daily aerosol alerts up to three days in advance. The alerts are computed based on an evaluation of each forecast, with different thresholds used to detect anomalies relative to reference levels and to describe events.