Indicator Fact Sheet

Emission trends of nitrogen oxides NOx

Indicator Fact Sheet
Prod-ID: IND-166-en
  Also known as: APE 002
This is an old version, kept for reference only.

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This page was archived on 31 Jul 2015 with reason: No more updates will be done

Assessment made on  01 Dec 2005

Generic metadata



DPSIR: Pressure


Indicator codes
  • APE 002

Policy issue:  Are we reaching emission targets for acidifying substances?

Key assessment

EEA-32 NOx emissions have decreased by 31% between 1990 and 2005. Reductions have occurred in all economic sectors apart from the other (non-energy) sector, where emissions have increased by 8% during this period. The three sectors responsible for the vast majority of the decline in NOx emissions are "road transport" (contributing 53% of the total reduction in NOx emissions reported by countries), "energy industries" (contributing 29%), and "industry (energy)" (contributing 15%).

Significant reductions have occurred in the "road transport" sector since the early 1990s (38% reduction between 1990 and 2005). This has been achieved despite the general increase in activity within this sector over the period. The emission reductions have primarily been achieved as a result of fitting catalysts to vehicles (driven by the legislative "Euro" standards). However, across Europe there is also an increasing awareness of the contribution made to NOx pollutant emissions by national and international ship traffic (a more detailed discussion of this issue is contained in the TERM indicator fact sheet TERM03 - Transport emissions of air pollutants).

Emissions of NOx have also declined in the "energy industries" (38% reduction between 1990 and 2005). In the electricity/energy production sector this has been achieved through the implementation of measures such as combustion modification, introduction of flue-gas abatement techniques and a fuel-switching from coal to gas. One of the most common forms of combustion modification is to use low NOx burners, which typically can reduce NOx emissions by up to 40%. Flue gas treatment techniques (e.g. NOx scrubbers and selective (SCR) and non-selective (SNCR) catalytic reduction techniques) can also be used to remove NOx from the flue gases. Emissions of NOx are higher from coal-fired power plants than from gas-fired plants as a result of coal containing significant amounts of nitrogen (unlike gas) and their less efficient combustion processes.

The newer Member States of the European Union have in a number of cases also undergone significant economic structural changes since the early 1990s which has led to a general decline in certain activities which previously contributed to high levels of NOx emissions e.g. heavy industry and the closure of older inefficient power plants.

The majority of EEA-32 countries have reported lower emissions of NOx in 2005 compared to 1990. The exceptions to this are Austria (7% increase between 1990 and 2005), Cyprus (19%), Greece (6%), Portugal (13%) and Spain (26%).


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