A5: Roadside nitrogen dioxide (NO2) concentrations

Final Final

Short description

This indicator tracks changes in average roadside concentration of nitrogen dioxide (NO2). NO2 arises predominantly from combustion sources such as traditionally fuelled vehicles and therefore the highest concentrations are often found at roadside locations.

This indicator is an assessment of clean air (reporting the condition of the atmosphere as an asset). It can also be considered as a pressure on human health. It is determined by calculating the average value of the annual mean concentrations measured across Defra’s Automatic Urban and Rural Network (AURN) at all roadside locations (with greater than 75% data capture in any one year).

Data are already published annually as National Statistics; Air Quality Statistics.

Trend description

Concentrations of roadside NO2 in England have fallen from 60 μg/m3 in 1997 to 30 μg/m3 in 2019, a drop of 49% over the latest 22 years for which data are available. Although the general trend in measured NO2 concentrations is decreasing and falls below the NO2 limit value of 40μg/m3 in recent years, there are hotspots of NO2 exceedances which are being addressed through the NO2 plans.


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

Indicator name

Roadside nitrogen dioxide (NO2) concentrations

Indicator reference


Outcome Indicator Framework theme


Headline indicator status

Not applicable

Relevant goal(s) in the 25 Year Environment Plan
  • Clean air
Relevant target(s) in the 25 Year Environment Plan
  • Meeting legally binding targets to reduce emissions of five damaging air pollutants
Position in the natural capital framework
  • Condition of assets - atmosphere
Related reporting commitments
  • Air Quality Standards Regulations 2010. Measurements from the UK AURN form part of the annual assessment of air quality against the limit and target values specified by this legislation
Geographic scope

England; data from individual monitoring sites are also available.

Status of indicator development


Date last updated

11 June 2021