European air pollution trends

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

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SULPHUR TRENDS
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Sulphur emissions 1980-2000
Countries SO2
CE Czech Rep., Hungary, Poland and Slovak Rep. -73
CW Austria, Switzerland and Germany -89
E Estonia, Latvia, Lithuania and Russia (European part) -73
N Denmark Finland Iceland, Norway and Sweden -87
NW Belgium, Luxemburg, the Netherlands, Ireland and United Kingdom -76
S France, Greece, Italy, Portugal and Spain -62
SE Albania, Armenia, Belarus, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Georgia, Kazakhstan, Republic of Moldova, Romania, Slovenia, The FYROM Macedonia, Turkey, Ukraine and Yugoslavia -40
TOTAL EUROPE (excluding ships ) -67
The decrease is not achieved in one single
sector, and is generally larger after 1990
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Episodes with high SO2 have decreased both in
frequency and magnitude
Daily means measured at SE02 1978-2000
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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.
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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?
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Sulphate formation is determined by availability
of oxidants (OH,H2O2,O3)
No oxidant limitation
With oxidant limitation
EMEP/MSC-W
EMEP/MSC-W
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Ammonia plays also a role in explaining sulphur
trends SO2/(SO4 airSO4
prec)
Increases the pH inside clouds (added effect to
SO2 concentration decrease) which affects the
oxidation rate from SO2 to SO4.
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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
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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
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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!)

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NITROGEN TRENDS
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Nitrogen emissions 1980-2000
Countries NOx NH3
CE Czech Rep., Hungary, Poland and Slovak Rep. -42 -46
CW Austria, Switzerland and Germany -49 -23
E Estonia, Latvia, Lithuania and Russia (European part) 21 -48
N Denmark Finland Iceland, Norway and Sweden -21 -10
NW Belgium, Luxemburg, the Netherlands, Ireland and United Kingdom -36 -13
S France, Greece, Italy, Portugal and Spain -4 1
SE Albania, Armenia, Belarus, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Georgia, Kazakhstan, Republic of Moldova, Romania, Slovenia, The FYROM Macedonia, Turkey, Ukraine and Yugoslavia -26 -12
TOTAL EUROPE (excluding ships ) -24 -20
Regional differences in N emission changes are
more pronounced than for sulphur emissions.
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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
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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
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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
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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.NH4NH3/SO4,
due to a changing atmospheric composition
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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
  NH3NH4/SO4

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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

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Comparison of oxidized and reduced nitrogen
trends 1980-2010
Sea areas
EMEP Land areas
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Influence of ship emissions in 2010to PM2.5 air
concentrations (CLE-15)
µg/m3 reduction
reduction
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Influence of ship emissions in 2010to SOMO35
(CLE 15)
ppb days reduction
reduction
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Concentrations in air (S,N)
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The contribution to PM10 mass from SO4 and NO3
dominates over NH4 contribution
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In addition to SIA, there is a primary and
organic component
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OZONE TRENDS
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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
CL3000 ppbh CL10000 ppbh
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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).

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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
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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
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Health exposure to ozone SOMO35
2000
2010
SOMO35 is high and will continue to be high
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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.

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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.

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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

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