Air quality issue

This case study focuses on the agricultural sector. In Flanders, ammonia (NH3) emissions from agriculture are the main source (74%) of atmospheric nitrogen deposited to sensitive ecosystems, including Natura 2000 sites. EU’s Natura 2000 network of protected areas is at the heart of the Birds and the Habitats Directives. Excess amounts of nitrogen can cause eutrophication, disrupting terrestrial and aquatic ecosystems and leading to changes in species diversity, for example in nutrient-poor grasslands.

Agricultural emissions in Flanders are also the largest local contributor to fine particulate matter (PM2.5) concentrations in the air, with a share of 43%. PM2.5 is the pollutant most harmful for human health.

Example of measures taken

To abate (NH3) emissions to the air, the technical measures in the Flemish air quality (AQ) action plan include for the agricultural sector:

  1. The introduction of an electronic monitoring system on air scrubbers in pig and poultry houses to ensure the proper functioning of these scrubbers (since 2021 for new installations and for all existing installations from 2025 onwards)
  2. Imposing a higher minimum removal efficiency for new air scrubbers
  3. Tightening the conditions for low-emission application of mixed manure on fields, combined with clear construction requirements (for example increase of manure injections from 26% to 50%)
  4. Improved rules for the use of urea as a fertiliser

The Flemish AQ plan is part of the implementation of the EU’s Ambient Air Quality Directive (PM limit and target values) and the National Emission reduction Commitment Directive (2020 and 2030 NH3 emission reduction commitments for Belgium).

Costs and trade-offs

A cost-benefit analysis has documented the expected cost of the technical measures to decrease the ammonia (NH3) emissions by about 80%. The costs per abated kilogram NH3 for the air scrubber measures are about 15 Euro for breeding pig houses, 9 Euro for fattening pig houses, 11 Euro for breeding poultry houses, and 16 Euro for fattening poultry houses. Reducing NH3 emissions from manure application by 90% are estimated to cost 0.7 Euro per square metre mixed manure.

The total investment costs cannot be calculated yet, as the measures still need to be (largely) implemented.

Use of injection or fast submersion of mixed manure improves the nitrogen efficiency of the manure use, lowering the need for additional fertilizer use.

One trade-off for air scrubbers is that they consume a relatively large amount of energy and water. Furthermore. their effectiveness depends on correct installation and settings. Imposing such a technical measure may lead to a lock-in whereby the farmer, due to large investments, can no longer take other measures, e.g., in the context of the Water Framework Directive. 

Who was involved?

The air quality action plan is a responsibility of the Flemish Department of Environment. Throughout the process of drafting the plan, sectoral federations and other stakeholders were involved in the discussions on actions that became part of the plan. A draft version of the action plan went through a public consultation process where all organizations, stakeholders and individual citizens had the opportunity to share comments and recommendations. The AQ action plan was approved by the Flemish regional Government in 2019.

The cost-benefit analysis for actions and scenarios to reduce nitrogen deposition was performed by VITO and ILVO (Flemish research organisations) for the Flemish Department of Environment.

Lessons learnt

  • Stakeholders involvement from the beginning helped to mutually agree on an approach to make steps towards a reduction of the air quality impact.
  • Overall, the package of measures does not lead to a drastic short term reduction of the agricultural emissions, but rather guides the way to a reduction pathway to reach the middle and long term goals. This proved to be the best balance between environmental, economic and technical boundary conditions.

Flanders, Belgium
Type of measure
Technical abatement of ammonia emissions
Target pollutants
Ammonia emissions (NH3), atmospheric nitrogen deposition
Pollution source targeted
The Flemish AQ plan 2030 (2019) and the first progress report (2021) 
Public consultation of the AQ plan


Geographic coverage


Filed under:
Filed under: agricultural emissions
Document Actions