A6: Exceedance of damaging levels of nutrient nitrogen deposition on ecosystems

Final Final

Short description

This indicator shows changes in average accumulated exceedance and percentage of sensitive areas exceeding the internationally agreed threshold for harmful effects (critical load) for nutrient nitrogen deposition across sensitive habitats. The damaging nutrient nitrogen comes predominantly from ammonia (NH3) but partly nitrogen oxides (NOx) and long-range transport of air pollutants.

This indicator is an assessment of clean air (reporting the condition of the atmosphere as an asset). It can also be considered as pressure on thriving plants and wildlife. It is determined by calculating the area of sensitive habitat exceeding the internationally agreed threshold for likely damaging effects from reactive nitrogen deposition in both oxidised and reduced forms, termed the critical load. It uses modelled interpolations of atmospheric concentrations of NOx and NH3 and models deposition processes based on internationally agreed methodology.

Assessments are undertaken and published annually using 3-year moving average data, at UK Air Information Resource: Trends in critical load and critical level exceedances in the UK.

Trend description

The percentage area of sensitive habitats in England where nutrient nitrogen deposition exceeded critical load has fallen over the latest 20 years for which data are available (98.3% in 1995-97 to 95.1% in 2016-18).


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This table provides metadata for the interim or final indicator presented above.

Indicator name

Exceedance of damaging levels of nutrient nitrogen deposition on ecosystems

Indicator reference


Outcome Indicator Framework theme


Headline indicator status

Not applicable

Relevant goal(s) in the 25 Year Environment Plan
  • Clean air
  • Thriving plants and wildlife
Relevant target(s) in the 25 Year Environment Plan
  • Meeting legally binding targets to reduce emissions of five damaging air pollutants
  • Restoring 75% of our one million hectares of terrestrial and freshwater protected sites to favourable condition, securing their wildlife value for the long term
Position in the natural capital framework
  • Pressure on natural capital assets
Related reporting commitments
  • International Collaborative Partnership reporting under UNECE’s Working Group on Effects
  • Convention on Biological Diversity (CBD) Aichi Target 8
Geographic scope


Status of indicator development


Date last updated

11 June 2021