Site Relevant Critical Loads and Source Attribution

New APIS Tool

A new APIS GIS map tool for Site Relevant Crtiical Loads & Search by Location has been developed in place of the look-up system below.

enter app

We welcome any comments or suggestions that you may have about the new APIS interface, you can suggest your changes or report any problems and select the option "APIS bugs & broken links".

To see a video demonstration on how to use this tool go here.

If you wish to keep using the look-up tables below then we are making that available until the new tool 'beds in'.

The pollution concentration and deposition data in the Site Relevant Critical Load Tool has been updated to use the 3-year mean for 2017-19.

The source attribution data is still based on 2012 emissions data.


About the Site Relevant Critical Loads Tool

The ‘Site Relevant Critical Loads’ tool provides critical loads for acidity and nitrogen for designated features within every SAC, SPA or A/SSSI in the UK. You can view an overview of each interest feature for each site. Critical loads are assigned to each sensitive feature for either nutrient nitrogen or acidity. Furthermore, deposition data for nitrogen and sulphur at each site are provided, apportioned to major sources, and presented in pie charts. You can also select a grid reference if you know the exact location of your feature within a site. Simply follow the screen below.

Search by SiteSelect a designation type and select 'Next'


Devon SAC
East Devon Pebblebed Heaths SAC
[photo: Clinton Devon Estates]