This project provides the key mechanism by which the scientific understanding of the effects of nitrogen and sulphur deposition on terrestrial and aquatic ecosystems is translated into policy-relevant predictions of the spatial extent and timescales of damage and recovery.  It brings together the mapping and modelling of critical loads and critical levels, pollutant deposition and concentrations, to generate critical load and critical level exceedance data.  Exceedance maps and statistics are updated annually to provide information on the areas of sensitive habitats and designated sites at risk from the adverse impacts of acidification and eutrophication.  Summary statistics by habitat and country (within the UK) are used to monitor progress in reducing the areas at risk from air pollution over time.

The project also provides the UK National Focal Centre (NFC) for critical loads mapping and modelling activities and is responsible for generating and submitting UK critical loads data in response to calls under the Working Group on Effects of the UNECE Convention on Long-Range Transboundary Air Pollution.

This work is funded by Defra under contract AQ0826: Mapping and Modelling of Critical Loads and Critical Levels Exceedance.