Critical Loads

CBED deposition (single years grid-average; 3-year rolling mean moorland and woodland)

UK Pollutant Deposition

Emissions of air pollutants have a wide range of effects in the environment. Poor air quality can affect human health, while deposition of air pollutants back to earth can affect ecosystems, changing biodiversity and reducing water quality. Air pollutants are removed from the atmosphere through ‘wet deposition’, by rain, snow and fog, and by "dry deposition", which is the direct uptake of gases and particles to land and water surfaces. This site provides access to UK sulphur, nitrogen and base cation deposition data and maps.


EIDC data record and mapped using WMS for individual years and 3-year rolling mean.

Summary critical load exceedance statistics

Trends in critical load exceedances

Exceedance is the amount of excess atmospheric deposition above the critical load. Exceedance maps and summary statistics are used by Defra and other bodies to guide policy development on the control of air pollutants, and to monitor progress in reducing the areas at risk from air pollution over time. Exceedances are calculated using UK 5x5 km resolution deposition data averaged over a three year period. The areas of habitats at risk are determined from the habitat distribution maps created for this project. The results summarise the trends in critical loads exceedances from 1995 to the present day.

Click here to for Acidity Results and Nutrient nitrogen Results

Further information


summary exceedance statistics by country

summary exceedance statistics by habitat and country

Summary exceedance statistics for the years: 1995-97, 1998-2000, 1999-2001, 2001-2003, 2002-2004, 2003-2005, 2004-2006, 2005-2007, 2006-2008, 2007-2009, 2008-2010, 2009-2011, 2010-2012, 2011-2013, 2012-2014, 2013-2015

Exceedance maps and data

Aim: to provide 1x1km spatial data of critical load exceedance maps for all habitats combined, ie. one map for acidity and one for nutrient nitrogen for each set of years exceedances are calculated for (ie. 1995-97 to present day 2013-15).