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; a more detailed description and analysis of the results can be found in the “Trends Report”. The trends in critical load exceedances for the period 2004-06 to 2011-13 were updated in May 2015 following changes made to the national deposition data sets; further details can be found here.