European transboundary air pollution is slowly shrinking

For most European countries the biggest share of depositions of sulphur and nitrogen emanate from outside their own territory, and a significant share of the depositions originate from international shipping.

Since 1980, total European emissions of sulphur dioxide (SO₂) – the most significant acidifying pollutant and an important precursor to health-damaging secondary fine particles (PM_2.5) – from land-based emission sources were cut by 90 per cent, from around 53 million tonnes in 1980 to 5.6 million tonnes in 2017.

In the same time period, emissions of nitrogen oxides (NOx) and non-methane volatile organic compounds (VOCs) have fallen by half, while those of ammonia (NH₃) came down only by a quarter.

Between 2000 and 2017 it is estimated that emissions of primary particulate matter (PM_2.5) were reduced by 24 per cent, from 2.6 to 2.0 million tonnes.

Although overall emissions continue to fall, the downward trend has flattened out over the last decade. This is especially the case for ammonia – which emanates primarily from agricultural activities – and PM_2.5, which are even reported to be increasing in some countries over the last few years.

Looking specifically at the 28 member states of the EU, between 1980 and 2017 emissions of SO₂ came down by 94 per cent, while those of NOx, VOCs and ammonia fell respectively by 57, 61 and 25 per cent. Emissions of PM_2.5 were reduced by 29 per cent between 2000 and 2017.

Air pollutant emissions from international shipping kept on steadily increasing during the 1980s and 1990s. However, the introduction of ship fuel sulphur standards, especially in the designated Sulphur Emission Control Areas (Baltic Sea and North Sea) from 2006, has resulted in a gradual decline in ship SO₂ emissions specifically in those northern sea areas. Over the last decade or so, NOx emissions from ships have also shown a slight downward trend, but because of the lack of effective ship NOx regulation they are likely to increase again as the economy and trade grow.

The data in Table 1 is based on figures reported by countries themselves to the Convention on Long-range Transboundary Air Pollution (LRTAP), and was compiled by the Centre on Emission Inventories and Projections (CEIP) of the European Monitoring and Evaluation Programme (EMEP). The Convention’s EMEP keeps track of the ways in which emissions from one country affect the environment in others. The EMEP report also provides an overview of calculations for source-receptor relationships (including transboundary movements between countries), covering acidifying, eutrophying, photo-oxidant, and particle pollution.

For most European countries the biggest share of depositions of sulphur and nitrogen emanate from outside their own territory, and a significant share of the depositions originate from international shipping.

Since land-based emissions have been falling much faster than those from international shipping, the proportion of pollutant depositions and concentrations contributed by shipping has been steadily rising in most countries. For 2017 it was estimated that ship emissions were responsible for up to 20–27 per cent of the total depositions of sulphur and oxidised nitrogen compounds (see Table 2). In the coastal areas of the affected countries, shipping’s contribution to the overall pollution load is even higher.

Table 2: The proportion of total air pollutant depositions of sulphur and oxidised nitrogen from shipping, for various countries in 2017.

It should be noted that the contribution of shipping to sulphur deposition in countries around the Baltic Sea and the North Sea decreased markedly after the entry into force of stricter fuel sulphur limits in those sea areas from 2015. Countries that are still particularly exposed to sulphur pollution from shipping include Portugal, Spain, Ireland, Italy and France.

Several more countries are highly impacted by ships’ NOx emissions, especially the Nordic countries, the Netherlands and Portugal, but also many Mediterranean countries as well as Ireland and the United Kingdom.

Christer Ågren

Report: “Transboundary particulate matter, photo-oxidants, acidifying and eutrophying components.” EMEP Report 1/2019. www.emep.int