A common framework for transboundary cooperation on air pollution
In the 1960s, scientists investigated the causes of “acid rain,” which was devastating forests, depleting fish populations in lakes, and threatening entire ecosystems across the Northern Hemisphere. They discovered that air pollutants — many emitted thousands of kilometers away — were the primary culprit.
To address this issue, 32 countries in the pan-European region decided to cooperate to reduce air pollution. In 1979, they signed the UNECE Convention on Long-range Transboundary Air Pollution, creating the first international treaty to deal with air pollution on a broad regional scale. The Convention, which entered into force in 1983, established the principles of international cooperation for air pollution control and created an institutional framework that has since brought together science and policy. Over time, the scope of the Convention and its protocols has expanded to include additional pollutants, such as ground-level ozone, persistent organic pollutants, heavy metals, and particulate matter.
The Convention has significantly influenced the evolution of international environmental law and serves as a vital framework for mitigating the harmful effects of transboundary air pollution on human health and the environment. It is a successful example of what can be achieved through intergovernmental cooperation.
| Title | ENG | FRE | RUS | |
|---|---|---|---|---|
| Text of the Convention | Status of Ratification |
Emission reductions
The collective efforts under the Convention have yielded remarkable results: emissions of several harmful substances have been reduced by up to 86% in the region since 1990. Notably, the reduction in sulphur emissions has significantly improved forest soil health, while the drop in emissions overall has decreased the deposition of acidifying compounds below critical acidity loads in much of Europe.
While nitrogen emissions have also been reduced, their decline has been less pronounced compared to sulphur emissions. Consequently, areas in Europe where forest soil acidification remains an issue are primarily impacted by nitrogen compound deposition.
Efforts to cut nitrogen oxides have significantly reduced lead pollution, with UNECE countries achieving an almost 80% drop in lead levels between 1990 and 2021, especially during the early years of the reduction efforts.
A common scientific understanding
A cornerstone of the Convention’s success has been its strong scientific foundation. This was built through the development of a shared knowledge base, supported by joint monitoring and modeling programs and an extensive international network of scientists from diverse disciplines. This collaborative approach not only advanced scientific understanding but also fostered mutual trust and learning between scientists and policymakers.
Early protocols under the Convention prioritized technological solutions to reduce emissions. However, protocols negotiated in the 1990s adopted an effects-oriented approach, aiming for cost-effective strategies to achieve reduction targets. This shift recognized the interplay between various air pollutants in the atmosphere, their combined impacts, and their shared sources. Consequently, a substance-by-substance approach was deemed inefficient, leading to the adoption of a multi-pollutant, multi-effect framework. The 1999 Gothenburg Protocol to Abate Acidification, Eutrophication, and Ground-level Ozone was the first to implement this innovative strategy.
Looking ahead
Air pollution knows no borders, making international coordination of air pollution policies essential.
Ratifying and implementing the Convention and its protocols offers many Parties a cost-effective way to mitigate health and environmental impacts. It also fosters economic benefits by harmonizing legislation and standards across countries, creating a level playing field for industries and preventing competitive practices that harm the environment and public health.
In recent years, a key priority for the Convention has been strengthening its implementation and expanding participation, particularly among countries in Eastern and South-Eastern Europe, the Caucasus, and Central Asia. UNECE carries out capacity-building activities that aim to elevate the political profile of the Convention in these regions and encourage ratification of its protocols. Recent amendments to key protocols have introduced flexibilities to facilitate accession by new Parties.
Air pollution impacts us all—damaging human health, undermining food security, hindering economic development, contributing to climate change, and degrading ecosystems vital to our livelihoods. The Convention remains a crucial platform for addressing these interconnected challenges and taking collective action to prevent further harm.