A7: Area of land exposed to damaging levels of ammonia (NH3) in the atmosphere

Final Final

Short description

This indicator tracks changes in land area affected by damaging levels of ammonia (NH3) in the air. Excess deposition of (NH3) on natural ecosystems causes nutrient enrichment and changes in vegetation and soils. Agriculture is the main source of (NH3) emissions to the atmosphere.

This indicator is a measure of pressure on ecosystems from air pollution. It shows the percentage of land area where interpolated measurements of ground-level air exceed the lower critical level threshold for (NH3) of 1 µg/m3.

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 of land area exposed to concentrations of NH3 that exceed critical levels (1 μg/m3) has decreased slightly from 88.9% in 2009-11 to 87.9% in 2015-17.


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

Indicator name

Area of land exposed to damaging levels of ammonia (NH3) in the atmosphere

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
  • United Nations Economic Commission for Europe National Emissions Ceiling Directive Art.9 and the Convention on Long-range Transboundary Air Pollution
  • Convention on Biological Diversity Aichi Target 8
Geographic scope


Status of indicator development


Date last updated

11 June 2021