Understanding Aviation’s Nitrogen Deposition Challenge

Compliance with nitrogen deposition regulations has recently become a pressing issue in the Netherlands due to changes to the permit process for activities in and around protected natural areas. Dutch airports are required to include any effect they have in their Environmental Impact Report. With permits now less clear-cut, understanding all aspects of the deposition calculations is more important than ever.

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Why nitrogen deposition is a problem

Nitrogen deposition is the input of reactive nitrogen from the atmosphere into the biosphere. It enters the soil from the emissions of burning fossil fuels and from agricultural sources such as fertilisers. Nitrogen deposition is greatest near highways and intensive farming. Although aviation is not the largest contributor, the industry’s use of fossil fuels does affect soil nitrogen levels.

Over the years, many of the areas now protected under the European Natura 2000 habitat conservation network have developed high concentrations of nitrogen. Too much nitrogen in the soil threatens plants, animals, birds and marine life. Also, as the levels increase, biodiversity decreases as sensitive native species are overtaken by less sensitive species.

Nitrogen Deposition Reporting

In 2015, the Dutch government introduced a permit process based on policy norms (Programma Aanpak Stikstof, or PAS) to regulate the negative effects of activities on Natura 2000 areas. Activities producing low-level nitrogen deposition (below 0,05 mole N/ha/year) were generally exempted. Higher depositions, up to a maximum level, required a special permit.

Recently, however, the State Council ruled that PAS did not comply with the European guidelines for habitat conservation because it allowed activities to take place in advance of mitigative measures. Permits and automatic exemptions based on the PAS norms are no longer valid. A good overview of the complex mix of landside and airside activities that must be evaluated within the deposition calculation is essential, also for the government officials who issue the permits.

Calculating Complex Activities

Dutch airports must submit an Environmental Impact Report, or MER as it is known in the Netherlands, when seeking government permission for operations changes such as increasing aircraft movements or adding charter flights at general aviation airports. That includes reporting on nitrogen deposition.

Nitrogen deposition from aviation depends on the level of aircraft emissions occurring in the mixed layer, the lowest part of the atmosphere. The mixing height varies between tens of metres at night to 2000m in bright sunlight. Nitrogen emissions above the mixed layer generally do not reach the earth’s surface. Where the deposition falls can be calculated using a tool that applies external factors such as wind direction, location and altitude to the emission sources. Other nitrogen deposition sources, such as roads to and from the airport and platform activities, should also be considered.

The complex mix of airport activities can be analysed for the nitrogen deposition calculation by applying the five principles below. Each principle should reveal important insights into which activities will result in nitrogen deposition.

      1. Determine all possible emission sources within a set boundary around the airport.
      2. Calculate nitrogen emissions for air traffic based on airplane types and routes within the set boundary.
      3. Calculate nitrogen emissions for platform-related traffic based on the mix of equipment needed for aircraft handling.
      4. Calculate nitrogen emissions from road traffic to and from the airport within the set boundary.
      5. Determine the appropriate deposition calculation method.


Applying these principles to help identify nitrogen deposition sources in detail is useful for determining where mitigative actions could have the greatest positive impact. For instance, investments in electric transportation in and around the airport near Natura 2000 areas could also help to reduce the total nitrogen deposition there.


About To70. 
To70 is one of the world’s leading aviation consultancies, founded in the Netherlands with offices in Europe, Australia, Asia, and Latin America. To70 believes that society’s growing demand for transport and mobility can be met in a safe, efficient, environmentally friendly and economically viable manner. To achieve this, policy and business decisions have to be based on objective information. With our diverse team of specialists and generalists to70 provides pragmatic solutions and expert advice, based on high-quality data-driven analyses. For more information, please refer to www.to70.com.

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