European air pollution trends 1980-2010 Leonor Tarras ón EMEP/MSC-W

1. European air pollution trends 1980-2010 Leonor Tarrasón EMEP/MSC-W Workshop on Review and Assessment of European Air Pollution Policies 25-27 October 2004, Gothenburg, Sweden

2. EMEP Assessment Part I : European Perspective EMEP Assessment Part II: National Assessment 20 national contributions, CCC, MSC-E, MSC-W, IVL Gun Löblad

3. Main questions addressed by the EMEP Assessment Report • What is the result of emission reductions for air quality ? • What are the reasons behind the trends and are the trends in line with current understanding? • What is the present status of environmental air quality and what is the need for further actions? Meteorologisk Instituttmet.no

4. SULPHUR TRENDS Meteorologisk Instituttmet.no

5. Sulphur emissions 1980-2000 The decrease is not achieved in one single sector, and is generally larger after 1990

6. Episodes with high SO2 have decreased both in frequency and magnitude Daily means measured at SE02 1978-2000

7. The seasonal variation of SO2 has changed GB04 DK03 Episodes occurred during winter. The decrease in SO2 concentrations has been larger in winter than in summer, most likely due to a larger emission decrease in the cold season. However, weather may also have contributed to the change.

8. Sulphate in air has also decreased, … but not as much as the sulphur emissions and SO2 in air FR05 FI04 IT04 How to explain this?

9. Sulphate formation is determined by availability of oxidants (OH,H2O2,O3) No oxidant limitation With oxidant limitation: EMEP/MSC-W EMEP/MSC-W Meteorologisk Instituttmet.no Meteorologisk Instituttmet.no

10. Ammonia plays also a role in explaining sulphur trends SO2/(SO4 air+SO4 prec) Increases the pH inside clouds (added effect to SO2 concentration decrease) which affects the oxidation rate from SO2 to SO4. Meteorologisk Instituttmet.no

11. Decreasing sulphur emissions have also resulted in decreased sulphate in precipitation The decrease in sulphate in precipitation is similar to that of particulate sulphate in air PL02 LV10 AT02

12. The reduced sulphate in precipitation has further resulted in: Generally, increasing pH in precipitation Decreased deposition Decreased dry and wet deposition to forests as measured in a Swedish throughfall monitoring network CZ01

13. SULPHUR • Overall decrease of emissions by nearly 70%, largest in Central European countries. • Sulphur dioxide concentrations have decreased accordingly. In addition, the frequency and magnitude of episodes has decreased and the seasonal variations have changed. • Sulphate concentrations in air and precipitation have not decreased at the same rate as the emissions. • This is because SO4 is a secondary pollutant controlled by chemical precursor & oxidant availability, pH dependences (…NH3!) Meteorologisk Instituttmet.no

14. NITROGEN TRENDS Meteorologisk Instituttmet.no

15. Nitrogen emissions 1980-2000 Regional differences in N emission changes are more pronounced than for sulphur emissions.

16. Comparison of ammonia and Nox emissions Million tons/year The decrease is lower than for sulphur, but is of the same magnitude for oxidised (NOx) and reduced (NH3) nitrogen

17. Sector allocation of emissions NOx emissions 1000 tons NO2/year NOx reductions mainly due to changes in combustion sectors (40%) and transport (25%) Decreased NH3 is due to activity changes and control measures in agricultural sector NH3 emissions 1000 tons/year

18. Trends are similar for total nitrate and total ammonium at most of the sites available, even if the local emissions reductions are different Total nitrates and ammonium at DK03 and GB02 Total nitrates and ammonium in precipitation at CH02 and FI04 As for sulphur, the most oxidised nitrogen oxide compound show a slightly lower decrease due to the decreased sulphur emissions leaving more of the oxidants in the atmosphere

19. Example: trends in Nordic countries Increases in total N deposition may be due to influence not only from local but also from more distant contributions. In addition, the changes may be due to changes in the rates of chemical interactions between pollutants p.e.NH4+NH3/SO4, due to a changing atmospheric composition Meteorologisk Instituttmet.no

20. NITROGEN - I • Overall decrease of emissions by 20-30%, similar for NOx and NH3 emissions. • As for sulphur, the most oxidized nitrogen compound (NO3) shows a less pronounced trend. This is probably due to the fact that reduced sulphur emissions leave a potential for further oxidation in the atmosphere. • Trends of ammonium in air and precipitation are more similar to trends nitrate in air and precipitation, that what national emission trends would suggest. The explanation is not straigthforward. • Less monitoring sites with long-term data, need for further studies to analyse the nitrogen trends also in relation to the ratios between NH3+NH4/SO4 Meteorologisk Instituttmet.no

21. NITROGEN -II • Some interesting differences: • Over land areas, reduced nitrogen depositions and air concentrations generally dominate over oxidized nitrogen (since 1995) • Over sea areas, oxidized nitrogen is the dominant form of nitrogen • …. This brings the attention to ship traffic emissions Meteorologisk Instituttmet.no

22. Comparison of oxidized and reduced nitrogen trends 1980-2010 Sea areas EMEP Land areas Meteorologisk Instituttmet.no

23. Influence of ship emissions in 2010to PM2.5 air concentrations (CLE-15%) μg/m3 reduction % reduction Meteorologisk Instituttmet.no

24. Influence of ship emissions in 2010to SOMO35 (CLE – 15%) ppb days reduction % reduction Meteorologisk Instituttmet.no

25. Concentrations in air (S,N) Meteorologisk Instituttmet.no

26. The contribution to PM10 mass from SO4 and NO3 dominates over NH4 contribution Meteorologisk Instituttmet.no

27. In addition to SIA, there is a primary and organic component Meteorologisk Instituttmet.no

28. OZONE TRENDS Meteorologisk Instituttmet.no

29. Surface ozone Threshold conc of O3 are exceeded over large parts of Europe Crops Forests Example from UK Mean AOT40 calculated for for the five years 1994-1998. Maps produced by M Coyle CL=3000 ppbh CL=10000 ppbh

30. Peak ozone vs. exceedance to critical levels AOT40 values for forests in Austria (April – September, daylight hours) • A reduction in peak ozone values during the 1990s is reported from several regions in Europe, while there is no clear trend in the exceedances of the critical level (expressed as AOT40). Meteorologisk Instituttmet.no

31. Trend evaluation for O3 Long-term trends for O3 are difficult to assess: - O3 is formed in the air via photochemical reactions between NOx and VOCs, closely linked to the weather situation and its variations between years. - The hemispheric background of O3 - determined by emissions and processes outside Europe - is a considerable source. Model calculation by R Derwent

32. Stations in the north and west show increasing hemispheric background concentrations , which partly counterbalance the reduced peak values. Data from Mace Head The risk for high ozone conc remains. Climate effects may increase the conditions for “ozone summers”

33. Health exposure to ozone: SOMO35 2000 2010 SOMO35 is high and will continue to be high … Meteorologisk Instituttmet.no

34. Ozone • The reduction in peak ozone values is in line with model predictions based on the decreased precursor emissions in Europe and is a very likely result of emission abatement. Intermediate ozone more difficult to reduce. • Stations in the North and West report increasing hemispheric background concentrations of 0.3-0.5 ppbv year-1. • The declining trend of the peak values is to some extent counterbalanced by the gradual rise in background ozone and may also be counteracted by climatic change giving higher risks of hot and ozone-rich summers. • Further policies to reduce the emission of all ozone precursors including the cross-continental, hemispherical perspective will be necessary to reduce the harmful effects from ozone on the environment, crops and human health. Meteorologisk Instituttmet.no

35. Conclusions I • Considerable reductions of air emissions since 1980 have resulted in improved air quality in Europe • Despite this considerable reduction, pollution levels are still high and exceedances of critical loads and levels still represent a significant risk for ecosystems and health. Meteorologisk Instituttmet.no

36. Conclusions II: • Improved understanding of the inter-relations between atmospheric air pollutants – PM,O3 policies need to consider links to other greenhouse gases and climate policies • In particular, more focus should be given to NH3 control • smallest level of reduction so far, • reduced nitrogen generally dominates over land areas • controls the formation and deposition of SIA • Sources outside Europe are becoming increasingly important (international ship traffic, aircraft emissions, intercontinental sources ) – Link to hemispheric scale and global change Meteorologisk Instituttmet.no