The Convention on Long-range Transboundary Air Pollution

Because air pollution knows no boundaries, emissions of air pollutants produced elsewhere can have an impact on local acidification, eutrophication and air quality. This highlights the need for international cooperation on air pollution issues such as in the Convention on Long-range Transboundary Air Pollution work. In 1979, some thirty nations signed the Convention on Long-range Transboundary Air Pollution (LRTAP convention). The Convention was formed within the ECE, the UN Economic Commission for Europe, of which all the countries of Europe are members, as well as the United States and Canada. It came into force in 1983, after ratification by the legislatures of the required two-thirds of the signatory states.

The convention was mainly established to tackle the issue of acidification of lakes in Scandinavia and Canada by aiming to reduce emissions of sulphur pollution which had become a transboundary problem. Subsequently, harmful effects on other ecosystems, such as forests, also came into focus. In the nineties, human health effects of air pollution became a growing concern. More recently, the interaction of climate change and air pollutants has become another topic to tackle for the Convention. Over the years, the number of substances covered by the Convention and its protocols has been gradually extended from sulphur and nitrogen compounds to ground-level ozone, persistent organic pollutants, heavy metals and particulate matter.

One example of the importance of the CLRTAP work during the last 40 years is source-receptor matrices. Although there was scientific evidence for the transboundary transport of air pollution, it was initially not so easy to separate local (national) deposition of air pollutants from imported deposition on a bigger geographic scale. Source-receptor matrices built on emission inventories, modelling and measurements can show how much of a country’s own emissions fall within its territory and demonstrate the transboundary fluxes from a selected country to other regions.

The critical load is defined as the highest annual deposition level at which adverse effects on natural ecosystems are unlikely to result in the long term. Critical loads vary greatly with soil type and other local characteristics. Critical load maps, showing modelled deposition value ranges that would protect ecosystems, have been developed since the early nineties and served an important role in supporting the negotiations of the 1994 Sulphur Protocol and the Gothenburg Protocol.

Integrated Assessment Modelling has another vital role in policy negotiations under the Convention. The goal is to facilitate the design of an international, cost-effective and effect-based policy, considering equity criteria as well as the relevant differences in environmental sensitivities. Nowadays, the integrated assessment models of air pollution have become increasingly complex, considering different pollutants, their interactions, and the effects of air pollution on different receptors. Receptors may either be environmental impacts, such as acidification or eutrophication, or health effects.

The work has been led by the International Institute for Applied Systems Analysis (IIASA) which developed the Regional Acidification Information and Simulation (RAINS) model and fostered collaboration between scientists in the East and the West. The RAINS model was used as a basis for protocol negotiations under the Convention. The RAINS model was later replaced by the Air Pollution Interactions and Synergies (GAINS) model. The GAINS model was developed to address emission control strategies that simultaneously address air pollutants and greenhouse gases to maximise benefits at all scales.

The work under the convention has also led to a common scientific understanding of the role of air pollutants. An important priority for the Convention in recent years has been the strengthened implementation of the Convention and its protocols, targeting more specifically parties from Eastern, South-Eastern Europe, the Caucasus, and Central Asia.

The work under the Convention has been successful in reducing emissions, specifically sulphur emissions. More work is needed to bring about a similar reduction in other pollutants.

Source: https://unece.org/sites/default/files/2021-06/1914867_E_ECE_EB_AIR_NONE_...