The convention has been successful at reducing air pollution, but more ambition is still needed to achieve the long-term objectives. Photo: / Gemma Llorensí CC BY

40 years of partnership for clean air

The Air Convention has developed and applied new tools resulting in cost-effective, effect-based strategies to tackle air pollution.

It was over fifty years ago that air pollution was identified as an environmental problem that was not limited by national borders, and one that required international co-operation. This fact laid the foundation for the drawing up of the Convention on Long-Range Transboundary Air Pollution (also known as the Air Convention), which was signed in Geneva on 12 November 1979, and is now celebrating its 40th anniversary.

The Air Convention, which covers 51 parties across Europe and North America, initiated a process that stimulated research and the international exchange of knowledge and information, which in turn spurred on political decisions on the measures needed to reduce emissions, both nationally and internationally. Since it was signed, the Convention has led to a series of agreements, known as protocols, which prescribe binding commitments on emission limits.

Since 1980, emissions of sulphur dioxide from land-based sources in Europe have fallen by nearly 90 per cent. Emissions of other air pollutants have also dropped, but not by anywhere near as much – nitrogen oxides and volatile organic compounds have fallen by roughly half, and ammonia by a quarter (see article on page 8).

It is naturally difficult, and perhaps impossible, to give a quantitative estimate of the proportions of these emission reductions that can be ascribed to the Air Convention, but there is no doubt that it has been a contributory factor.

The work carried out under the Convention has had a consistently strong scientific basis, particularly the mapping out and description of air pollutant emissions, transport, deposition and environmental effects. During the 1980s and 1990s the Convention also developed and applied new tools, such as critical loads (scientifically derived limits to Nature’s tolerance to pollutant exposure) and integrated assessment modelling, which in turn led to the development of cost-effective, effect-based strategies to tackle the problems.

The Air Convention’s data and methods of work were used also by the European Commission and the EU member states when developing the National Emission Ceilings Directives of 2001 and 2016.

In a recent article in Ambio, a group of experienced scientists and policy-makers concludes that the close involvement of scientists has been a signature of the Air Convention. They also note that during all interactions between science and policy, it is of critical importance that scientific credibility is maintained.

Scientists have continuously had a role at the Convention’s policy meetings, where they communicate results from basic air pollution research, report on outcomes of monitoring and inventories, and present options for control strategies. In this way, scientists have taken responsibility for bringing up-to-date scientific knowledge into the policy negotiations and presenting results in a way that has been understandable and useful for the policy work.

The authors also note that public awareness is important for promoting stronger interest and putting pressure on decision-makers, and that NGOs have played an important role in spreading awareness of air pollution more widely, and could therefore be important for a more global movement towards cleaner air.

The latest agreement under the Air Convention – the Gothenburg Protocol as amended in 2012 – was put together according to this model of science-policy interaction, and it sets binding national emission reduction commitments for five pollutants (SO2, NOx, VOCs, NH3 and PM2.5) that must be achieved by 2020.

However, even when the Protocol was signed in 2012 it was obvious that the agreed emission reductions, the outcome of political compromises, were clearly insufficient to achieve the long-term objectives of not exceeding critical loads and protecting people’s health. It is therefore expected that there will be a process of review and revision in which emission limits are progressively strengthened.

After the eighteenth ratification, the Protocol came into force on 7 October. There are currently 22 parties to the Protocol, and the number is growing.

The entry into force opens the way for a review and revision of the Protocol – an issue that will be debated at the next meeting of the Convention’s Executive Body on 9–13 December in Geneva. On 11–12 December, the meeting will also hold a special session to celebrate the Air Convention’s 40-year anniversary.

Christer Ågren

The Convention’s website:
Ambio article: “Acid rain and air pollution: 50 years of progress in environmental science and policy” (August 2019). By P. Grennfelt, A. Engleryd, M. Forsius, Ø. Hov, H. Rodhe & E. Cowling. Link:


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