All official European Union website addresses are in the europa.eu domain.
See all EU institutions and bodiesDo something for our planet, print this page only if needed. Even a small action can make an enormous difference when millions of people do it!
In the following, air quality summaries are presented compound-wise: sulphur compounds, nitrogen compounds, black smoke, suspended particulate matter, ozone, lead, carbon monoxide. Only for sulphur and nitrogen compounds, regional data summaries are presented. For the other compounds, regional data of sufficient extent have not been available in preparing this report.
6.1. Sulphur compounds
6.1.1. Behaviour, effects, emissions
Sulphur dioxide (SO2) and particles emitted from the combustion of sulphur containing fuels are major air pollutants in urban areas, and SO2 is the principal pollutant associated with the acid deposition problem. Sulphur oxides and particulate matter are parts of a complex pollutant mixture, and are often considered together, since their effects cannot be distinguished from each other. In guidelines, the following categories are considered:
In urban air dominated by local emissions, SO2 is the most abundant sulphur compound. Urban SO2 occurs in short term concentrations typically up towards several hundred µg/m3, and in extreme cases up to several thousands µg/m3. It is oxidised through several steps, via HSO3 to various forms of sulphates (sulphuric acid, ammonium sulphate and others). These reactions are fairly slow (in the range a few % per hour, dependent upon the composition of the ambient air). In highly polluted atmospheres, SO2 may enter into photochemical reactions, which are also rather slow. Removed from the vicinity of sources (as in regional air pollution), SO2 and sulphates often occur in concentrations of about equal magnitudes, in Europe up towards 30 µg/m3 as long term averages.
In periods with regionally poor dispersion and increased emissions, short term regional SO2 and particle concentrations may occasionally reach several hundred µg/m3.
SO2 and sulphates are removed from the atmosphere through wet and dry deposition, causing acidification of water and soil. Wet deposition of particulate sulphur dominates the total deposition.
Health effects of sulphur in air is caused by the absorption of SO2 on the mucous membrane of the nose and upper respiratory tract, and the deposition of sulphate aerosol in the respiratory tract. SO2 causes acute severe effects in the bronchii at very high concentrations (>10,000 µg/m3). Asthmatics experience effects at much lower concentration. Epidemiological studies indicate possible small reversible declines in childrens lung function at 250-450 µg/m3, and increased mortality at 500-1,000 µg/m3. Sulphuric acid cause human health effects, with a lowest demonstrated effects level of 100 µg/m3 on exercising adolescent asthmatics. High concentrations (>1,000 µg/m3) together with elevated particulate matter concentrations are believed to have been responsible for high mortality during smog episodes such as in London in 1952.
Acid deposition can affect terrestrial and aquatic ecosystems, if the deposition exceeds the critical load of the area. Effects include needle loss of conifers, and fish death. SO2 have a direct effect on vegetation at high concentrations (>some thousand µg/m3). SO2 plays an important role in the deterioration of stonework and metal corrosion.
Major SO2 sources in Europe are fossil fuel combustion for public power production and heating (54%) and small-scale heating (11%), industrial combustion (25%), and industrial processes (3%). (Percentage figures refer to the CORINAIR inventory, 1990).
The trend in SO2 emissions in Europe, as calculated for the EMEP area by the EMEP Meteorological Synthesizing Centre - West (Berge et al., 1995) is shown in Figure 6.1.
Figure 6.1: Emissions of sulphur dioxide in
Europe, 1980-1993.
(Ref.: Berge et al., 1995).
The calculated emissions were 40% lower in 1993 than in 1980, and the downward trend has been fairly steady over the entire period.
For 1990, there was good agreement between the EMEP and CORINAIR emissions data for each of 23 European countries (Berge et al., 1995).
6.1.2. Air Quality Limit and Guide Values
The complete EU Limit and Guide values for SO2 with associated values for black smoke and suspended particulates are given in Table 6.1 together with Guideline values for Europe given by WHO.
Table 6.1: EU Limit and Guide Values for SO2
and associated values for BS (black smoke) and suspended particles (gravimetric) (µg/m3)
EU Council Directives 80/779/EEC and 89/427/EEC.
WHO Guideline values for SO2 (µg/m3).
SO2 | Associated values for BS | Associated values for suspended particles | ||||
Limit Values | Median
of 24 h values |
98 percentile of 24h values | Median
of 24h values |
98 percentile of 24h values | Median
of 24h values |
98 percentile of 24h values |
Year | 80 | >40 | >150 | |||
Year | 120 | <40 | <150 | |||
Winter | 130 | >60 | >200 | |||
(1.10.-31.3.) | 180 | <60 | <200 | |||
Year | 2501 | >150 | >350 | |||
Year | 3501 | <150 | <350 | |||
Guide Values | Mean of 24h values | Maximum 24h average | ||||
Year | 40-60 | 100-150 | ||||
WHO Guideline Values | Max. 10 min average | Max. 1 h average | ||||
Reference period not specified | 500 | 350 |
1 EU Member States must take all appropriate steps to ensure that this value is not exceeded for more than three consecutive days. More over, EU Member States must endeavour to prevent and to reduce any such instances in which this value has been exceeded.
WHO Guideline values for Europe for combined exposure to SO2 and particulate matter (BS, TSP or TP) (EHO, 1987).
Substance | Mean values for averaging time | |
24 h | 1 year | |
SO2 | 125 | 50 |
BS1) | 125 | 50 |
TSP2) | 1203) | |
TP4) | 703) |
1) Black smoke
2) Total suspended particulates measured by high volume sampler without any size selection.
3) Value to be regarded as tentative at this stage.
4) Thoracic particles measured by a sampler having a 50% cut-off at 10 µm.
The WHO Guideline values are maximum values. They are not to be exceeded.
6.1.3. Urban and Local SO2 concentrations
Concentrations
SO2 data with associated values for black smoke and/or suspended particles from cities all over Europe are given in detailed tables in Appendix B. The data are from the APIS and EoI data bases and from national reports.
In Appendix B SO2 data from 17 countries are given. The stations are ranged according to the 98 percentile daily values. The stations with the highest values are given in Table 6.2. Also the maximum and median values are given, if available.
Figure 6.2 clearly shows the rather low concentrations in the Nordic countries. The highest 98 percentile and median values are observed in Germany (eastern part), the Czech Republic and in the Mediterranean countries.
Data from the selected cities in Figure 5.1/Table 5.2 are shown in Figure 6.3-Figure 6.6. These figures give the median, mean, 98 percentile and maximum values based on 24h values. These data indicate the highest SO2 levels in Germany and the eastern part of Europe.
Table 6.2: Maximum, 98 percentile and median SO2 values for 1993 for European cities ranged according to the 98 percentile values (µg/m3).
Country |
Name |
City Class |
Station |
SO2 24 hour values | ||
Maximum | 98 percentile | Median | ||||
Germany | Chemnitz | Zwickau-Zentrum | 570 | |||
Germany | Chemnitz | Chemnitz-Mitte 1 | 470 | |||
Germany | Leipzig | Leipzig-Mitte 2 | 460 | |||
Germany | Leipzig | Delitzch | 410 | |||
Germany | Chemnitz | Chemnitz-Mitte 2 | 393 | |||
Germany | Dresden | Pirna | 342 | |||
Germany | Greiz | Greiz | 321 | 54 | ||
Germany | Chemnitz | Plauen 2 | 317 | |||
Germany | Dresden | Dresden-Ost | 281 | |||
Germany | Altenburg | Altenburg | 270 | 42 | ||
Czech Republic | Prague | Námesti Republiky | 460 | 266 | ||
Portugal | Porto | Fac. Engenharia | 266 | 257 | 25 | |
Germany | Weimar | Weimar, Goeth. | 254 | 37 | ||
Germany | Dresden | Dresden-Mitte | 254 | |||
Germany | Dresden | Zittau-Ost | 253 | |||
Germany | Leipzig | Leipzig-Mitte 1 | 250 | |||
Germany | Gera | Gera, Frieder. | 247 | 45 | ||
Czech Republic | Prague | Riegrovy sady | 457 | 228 | ||
Italy | Porto Torres | Rio Mannu | 223 | 6 | ||
Germany | Erfurt | Erfurt, Krämpf. | 222 | 28 | ||
Germany | Dresden | Zinnwald | 220 | |||
Spain | Madrid | 1 | Cuatro Caminos | 288 | 216 | 41 |
United Kingdom | Belfast | 4 | Belfast centre | 354 | 213 | 29 |
Germany | Cottbus | 6 | Cottbus-Süd | 345 | 198 | 32 |
Czech Republic | Prague | Pocernicka | 442 | 194 | ||
Germany | Cottbus | 4 | Cottbus-City | 375 | 192 | 23 |
Italy | Genova | Enel 1 (Ponte Etiopia) | 192 | 47 | ||
United Kingdom | Liverpool | 4 | Liverpool centre | 200 | 189 | 24 |
Germany | Brandenburg | 5 | Brandenburg-Zentrum | 235 | 184 | 21 |
Germany | Dresden | Radebeul-Wahnsdorf | 183 | |||
Czech Republic | Prague | Vysocany | 524 | 178 | ||
Czech Republic | Prague | Výstavite | 495 | 178 | ||
Czech Republic | Prague | Mlynárka | 175 | |||
Germany | Braunschweig | 4 | Schlosspark | 316 | 174 | |
Czech Republic | Ostrava | Ostrava-Slez.Ostrava | 433 | 171 | ||
Czech Republic | Prague | Veleslavin | 513 | 170 | ||
Greece | Athens | 1 | Patission 147 | 327 | 170 | 52 |
Germany | Braunschweig | 4 | Am Sackring | 329 | 167 | |
Portugal | Carregado | Faiel | 210 | 165 | 9 | |
Italy | Siracusa-Augusta | Farodromo | 164 | 20 | ||
Portugal | Tapada Outeiro | Medas | 502 | 163 | ||
Germany | Cottbus | 5 | Cottbus-LUA | 292 | 162 | 17 |
Germany | Eisenach | Eisenach | 158 | 13 | ||
Italy | Venezia (ind. zone) | Stab. Sirma | 153 | 26 | ||
Germany | Berlin | Charlottenburg | 179 | 152 | 29 | |
Germany | Hannover | 3 | Welfenplatz | 248 | 151 | |
Czech Republic | Prague | Kobylisy | 498 | 150 |
Figure 6.3: SO2 median 24h values in selected cities (µg/m3).
Figure 6.4: SO2 mean values in selected cities (µg/m3).
Figure 6.5: SO2 98 percentile values based on 24h values in selected cities (µg/m3).
Figure 6.6: SO2 maximum 24h values in selected cities (µg/m3).
Exceedances
Table 6.3 shows stations with exceedances of EU Limit Values for SO2 for combined exposure to sulphur dioxide and black smoke/particulate matter. Some other stations in eastern Germany, which have only reported 98 percentile 1/2h values, may also have 98 percentile 24h values above 250 µg/m3 . A few stations in Prague reporting 95 percentile 24h values probably have 98 percentile 24h values above the EU Limit Value. The available data statistics from national reports do not usually give (enough) information about exceedances of EU Limit Values.
Table 6.4 shows stations with exceedances of EU Guide values and WHO Guideline values for SO2 for combined exposure to sulphur dioxide and black smoke/particulate matter. Stations marked with * show exceedance of WHO Guideline values. Stations in bold show exceedance of the upper EU Guide value.
The table shows that a great number of European cities in many countries have mean values and especially maximum 24h SO2 concentrations well above EU Guide values and WHO Guideline values. Especially Czech values, but also some Germany values are very high.
Table 6.3: Exceedances of EU Limit Values for SO2.
Country |
City |
Station name |
24h values | ||
1 year | 1 year | Winter | |||
Median >80 |
P98 >250 |
Median >130 |
|||
France | Lyon | Lyon Berthelot | 80 | ||
Germany-Thüringen | Altenburg | Altenburg |
|
||
Greiz | Greiz |
|
|||
Weimar | Weimar, Goeth. |
|
|||
Portugal | Porto | Fac. Engenharia |
|
* April 1993-February 1994.
Table 6.4: Exceedances of EU and WHO Guide Values for SO2.
Country | City | Station | Mean > 40-60 |
Max.
24 h > 100-150 |
Czech Republic | Ostrava | Ostrava-Slez.Ostrava |
|
|
Prague | Branik |
|
||
Kobylisy |
|
|
||
Mlynárka |
|
|||
Námesti Republiky |
|
|
||
Pocernicka |
|
|
||
Riegrovy sady |
|
|
||
Santinka |
|
|
||
Veleslavin |
|
|
||
Vrovice |
|
|
||
Vysocany |
|
|
||
Výstavite |
|
|
||
France | Lille | Tourcoing |
|
|
Lyon | Croix rousse |
|
||
Lyon Berthelot |
|
|
||
Lyon Garibaldi |
|
|||
Lyon Puits Gaillot |
|
|||
Saint Just |
|
|||
Marseille | Paradis |
|
||
Rabatau |
|
|||
Paris | Neuilly/Seine (92) |
|
||
Paris 13ème et. |
|
|||
Paris Ch. de Mars |
|
|||
Paris Tour St-Jacques |
|
|||
Strasbourg | Hoerdt |
|
||
Reichstett |
|
|||
Rue du 22 novembre |
|
|||
Germany | Altenburg | Altenburg |
|
|
Berlin | Charlottenburg |
|
|
|
Frankfurter Tor |
|
|||
Neukölen |
|
|||
Schöneberg |
|
|||
Wedding |
|
|||
Brandenburg | Brandenburg-Nord |
|
||
Brandenburg-Zentrum |
|
|||
Braunschweig | Am Fernmeldeturm |
|
||
Am Sackring |
|
|||
Schlosspark |
|
|||
Cottbus | Cottbus-City |
|
||
Cottbus-LUA |
|
|||
Cottbus-Süd |
|
|||
Dortmund | Dortmund-Asseln |
|
||
Dortmund-Hörde |
|
|||
Dortmund-Mitte |
|
|||
Duisburg | Duisburg-Buchholz |
|
||
Duisburg-Kaldenhausen |
|
|||
Duisburg-Meidenrich |
|
|||
Duisburg-Walsum |
|
> 40-60 | > 100-150 | |||
Germany (contd.) | Düsseldorf | Düsseldorf-Einbrungen |
|
|
Düsseldorf-Genresheim |
|
|||
Düsseldorf-Lörick |
|
|||
Düsseldorf-Mörsenbroich |
|
|||
Düsseldorf-Reisholz |
|
|||
Erfurt | Erfurt, Krämpf. |
|
||
Essen | Essen-Altendorf |
|
||
Essen-Bredeney |
|
|||
Essen-Leithe |
|
|||
Essen-Ost |
|
|||
Essen-Vogelheim |
|
|||
Gera | Gera, Frieder. |
|
||
Greiz | Greiz |
|
||
Halle | Halle |
|
|
|
Hamburg | 06, LO Lokstedt |
|
||
09 RA, Rahlstedt |
|
|||
11 HO, Hochkamp |
|
|||
12 BA, Bahrenfeld |
|
|||
13 ST, Sternschanze |
|
|||
14 LS, Lübecker Strasse |
|
|||
15 HR, Horner Rennbahn |
|
|||
18 WA Waltershof |
|
|||
19 SW, Steinwerder |
|
|||
20 VE, Veddel |
|
|||
21 BI, Billbrook |
|
|||
26 KI, Kirchdorf |
|
|||
27 Ta, Tatenberg |
|
|||
30 GT, Göhlbochtal |
|
|||
Hannover | Fischeteichweg |
|
||
Göttinger Strasse |
|
|||
Welfenplatz |
|
|||
Köln | Köln-Chorweiler |
|
||
Köln-Riehl |
|
|||
Köln-Rodenkirchen |
|
|||
Köln-Vogelsang |
|
|||
Magdeburg | Magdeburg |
|
|
|
Rostock | Rostock-Holbein Platz |
|
||
Saarbrücken | Saarbrücken-Eschberg |
|
||
Saarbrücken-Stadtmitte |
|
|||
Schwerin | Schwerin (Burmeister-Bade-Platz) |
|
||
Schwerin-UBA |
|
|||
Weimar | Weimar, Goeth. |
|
||
Greece | Athens | Patission 147 |
|
|
Pireas Platia Dinotikou |
|
|
||
Smyrni Cementry |
|
> 40-60 | > 100-150 | |||
The Netherlands | Ligging voor Achtergrondmetingen | Zaaidijk-Axel |
|
|
Rotterdam | Schiedamsevest |
|
||
Sas van Gent | Westkade |
|
||
Vlaardingen | Floreslaan |
|
||
Lyceumlaan |
|
|||
Portugal (contd.) | Area Sines | Santiago |
|
|
Barrero/Seixal | Av. da Praia |
|
||
Camara Municipal |
|
|||
Carregado | Cast. Ribatejo |
|
||
Faiel |
|
|||
TAK |
|
|||
Vinha |
|
|||
Estarreça | Teixugueira |
|
||
Lisboa | Beato |
|
||
Jerònimos |
|
|||
R. Sèculo |
|
|||
Porto | Fac. Engenharia |
|
|
|
Setúbal | Setenave |
|
||
Tapada Outeiro | Aldeia Nova |
|
||
Lever |
|
|||
Lixa |
|
|||
Medas |
|
|||
Vila Cova |
|
|||
Slovakia | Bratislava | Karmenné námestic |
|
|
Marmateyova |
|
|||
Trnavské mýto |
|
|||
Turbinová |
|
|
||
Koice | Podhvadová |
|
||
Strojárenská |
|
|||
túrova |
|
|||
Spain | Barcelona | Molina Pl. |
|
|
Prat del Llobregat |
|
|
||
Bilbao | Gecho |
|
||
Lab. Sanidad |
|
|||
Madrid | Arturo Soria |
|
||
Carlos V |
|
|||
Cuatro Caminos |
|
|
||
Plaza Castilla |
|
|||
Plaza España |
|
|||
Tenerife | Santa Cruz |
|
|
|
Switzerland | Zürich | Schimmelstrasse |
|
|
United Kingdom | Belfast | Belfast centre |
|
|
Birmingham | Birmingham centre |
|
||
Cardiff | Cardiff centre |
|
||
Edinburgh | Edinburgh centre |
|
||
Leeds | Leeds centre |
|
||
Liverpool | Liverpool centre |
|
|
|
London | London Bloomsbury |
|
||
Newcastle | Newcastle centre |
|
Mean: *) > 50 WHO Guidelines Max: *) >125 WHO Guidelines.
Trends
Figure 6.7-Figure 6.10 show, as examples, trends in the SO2 data on an annual basis for some selected stations in different countries. The figures show the maximum, 98 percentile and median of 24 h values from Norway, Denmark, the Netherlands, Spain and Greece. German data (from Bremen) show 98 percentile and mean values based on œ h values, while Swiss data show 95 percentile and mean values based on œ h data. Each of the trend figures covers a part of the period 1976-1994.
Most stations show a downward trend in SO2-concentrations. The downward trend is very clear in Norway, Denmark, the Netherlands and Switzerland. In Germany (Bremen) and Spain the downward trend is less pronounced. In Greece (Athens) top values have increased and median and mean values have been rather stable at a relatively high level compared to other countries.
For East Europe there are no trend data available to us.
Figure 6.7: SO2 trend in Norway 1977-1993 (µg/m3). Data from national reports.
Figure 6.8: SO2 trend in Aalborg, Denmark 1983-1994 and Amsterdam, the Netherlands, 1976-1994 (µg/m3), APIS data.
Figure 6.9: SO2 trend in Athens, Greece 1983-1993 and Madrid, Spain, 1986-1993 (µg/m3), APIS data.
Figure 6.10: SO2 trend in Bremen, Germany, 1987-1993 and from Switzerland, 1984-1993 (µg/m3). Data from Bremen State and Swiss reports. The figures are based on œ h values.
6.1.4. Regional sulphur oxides concentrations and deposition
The EMEP measurement programme started in 1978. There were 99 monitoring stations in operation in 1993 in 26 countries. 77 stations reported precipitation data and 92 stations reported air concentration data during 1993.
A short description of the EMEP programme, including station list, is given in Appendix C.
The following presentation is based directly upon the 1993 EMEP data report (EMEP, 1995).
Data presentation
Annual averages of the 1993 air and precipitation data are presented in maps. The yearly precipitation mean concentrations are calculated from the daily values as precipitation-weighted averages. Average air concentrations are arithmetic averages of the daily means.
Kriging procedure
The concentration fields have been calculated using kriging methods. The EMEP grid is divided in 9 subareas. During the kriging process each area consists of 11x11 grid elements. In addition, 3 grid elements were added on each side of the sub-area in order to get an overlap and thus obtain a smooth concentration field for the whole area. After calculation on each of the sub-areas, consisting of 17x17 grid-elements, the results for each of the original 11x11 elements were concatenated to one 33x33 element concentration field. One grid element is 150 km x 150 km. In the kriging process, the averages are expressed through random functions. Separate calculations on nine subgrids rather than one calculation over a large grid area reduces the effects of the systematic concentration differences present in Europe.
Concentrations
Sulphur dioxide
The EMEP sites have been located away from local sources and are as far as possible representative for a larger region. One consequence of this is that the sulphur dioxide concentrations in Europe is higher in industrialised regions than the concentrations shown in Figure 6.11.
The lowest concentrations of SO2 during 1993 are found on the Atlantic coast in Ireland and in northern Scandinavia, where the averages are lower than 0.5 µg S/m3. From the United Kingdom eastward the concentrations increase from mainly 12 µg S/m3 to the highest SO2 concentrations measured in the network, in the area of eastern Germany, southern Poland, the Czech Republic, Slovakia and the north eastern part of Austria. In this region the annual average of SO2 in rural areas is above 5 µg S/m3, and peaks around 10 µg S/m3 are seen at one German and one Czech station. In Germany and Poland the concentrations decrease towards the north.
The concentrations of SO2 over the western part of Russia, the Baltic and southern Scandinavia are in the range 1 to 2.5 µg S/m3. Romania and Bulgaria do not take part in the measurements, and there is only one site in Greece. For this reason the kriged concentrations in this area are very uncertain and are thus removed from Figure 6.11. The situation is similar in the southern half of Italy. Relatively low concentrations are seen over France and central Spain.
The regional concentrations in central Europe (>10 µg SO2/m3, annual average) are higher than in most cities of Scandinavia and parts of North-western Europe.
Sulphate in aerosol
Figure 6.12 presents the annual averages of sulphate in aerosols in 1993. Large parts of Ireland and Scandinavia have averages lower than 0.5 µg S/m3. Towards south and east the concentrations increase to 11.5 in southern England to Denmark, southern Sweden and the Baltic. Most parts of western Europe experience concentrations in the range 12 µg S/m3. The highest concentrations are observed over south-eastern Europe, more than 8 µg S/m3 at one station in Greece and around 4 µg S/m3 at one station in Hungary. However, the sites in this area are relatively few and the inaccuracies are thus large. In Portugal and Spain the averages increases from 11.5 µg S/m3 in the north to 1.52 µg S/m3 in the south.
Figure .11: Sulphur dioxide in rural areas 1993, annual average (µg
S/m3).
Factor 2.0.
Figure .12: Sulphate in aerosols 1993, annual average (µg S/m3).
Factor 3.0.
Wet deposition
Sulphate in precipitation
Sulphate in precipitation, corrected for sea-salt contributions are presented in Figure 6.13. As for most other pollutants of anthropogenic origin, the lowest concentrations are seen at the Atlantic coasts of Portugal and Ireland and in northern Scandinavia. Most of the Continent is exposed to annual averages less than 1 mg S/l. As for sulphate in aerosol phase, the region with higher concentrations stretch over the eastern parts of Europe, around 1.5 mg S/l or higher at stations in Croatia, Hungary, Poland and Yugoslavia. There is also a station in Ireland with concentrations at the same level. In Portugal and Spain there is a west to east increasing gradient, with a concentration of about 1 mg/l in the eastern parts.
pH in precipitation
The annual averages of pH in precipitation are presented in Figure 6.14. Over most parts of Europe the pH is lower than 5. The lowest pH values are seen in Poland and in middle Sweden; below 4.4, equivalent to an acid concentration of 40 µeql. Towards southern Europe there is in general an increase of pH.
Calcium in precipitation
Both industrial emissions of fly ash and other mineral particles, and soil dust are sources for calcium in precipitation, Figure 6.15. The high concentrations in southern Europe are mainly derived from soil dust, from wind erosion in the Sahara desert, and from local sources. The calcium content in both soil and rocks is high in many places in southern Europe. In eastern Europe industrial emissions, e.g. from cement plants, steelworks and power plants, give rise to concentrations of 10-20 µg/l of Ca in precipitation, while the concentrations of calcium in precipitation is low in the northern part of Great Britain and in most of Scandinavia and Finland. Calcium and other base cations increase the pH of precipitation.
Figure 6.13: Sulphate in precipitation 1993 (mg S/l).
Figure 6.14: pH in precipitation 1993 (pH units).
Figure 6.15: Calcium in precipitation 1993 (µg Ca/l).
Trends for the years 1985-1993
The EMEP Meteorological Synthesizing Centre-West (The Norwegian Meteorological Institute) has calculated sulphur reduction trends with distance from major emission sources for the period 1985-1993.
The EMEP-monitoring network have been classified into three broad groups. Stations have been grouped geographically according to the average straight-line distances of transport of deposition. "Long distance" sites are those lying approximately 1000 km or more on average from deposition quantity weighted sources, "medium distance" sites are those at between 500 km and 1000 km, and "short distance" stations are those under 500 km on average from sources. For sulphur dioxide, airborne sulphate, and sulphate in precipitation average monitored and modelled concentrations are plotted. The selection criteria for sites is as standard, i.e. that model and monitored results must be available on 25% of common days for precipitation results, and that air quality results must be reported for 75% of days. The further constraint is that stations must satisfy the criteria during each of the years. The time period considered is from 1985 to the end of 1993 for SO2 and SO4= in air, with 1992 the final date for sulphate in precipitation due to a lower number of stations reporting results at time of analysis.
Figure 6.16-Figure 6.18 show observed and modelled levels and trends of SO2 in air, sulphate in air and sulphate in precipitation.
The main conclusions from this trend analysis, are:
The analysis show some discrepancies between the measured and modelled results.
It should also be noticed that the trend analysis has been done on a selected and rather limited set of sites (as shown in the figures), selected based on the criteria mentioned above. No analysis has been published on possible differences in trend between various parts of Europe.
The reduced SO2 concentrations in regional air over Europe coincides well, on the macro scale, with the reduced SO2 emissions described earlier in this chapter.
Figure 6.16: Time trend comparison for SO2 in
air across the EMEP network.
a) Short distances from sources (<~500 km).
b) Intermediate distance (~500-1000 km).
c) Longer distances from sources (>~1000 km).
Figure 6.17: Time trend comparison for SO4= in air across the EMEP
network.
a) Short distances from sources (<~500 km).
b) Intermediate distance (~500-1000 km).
c) Longer distances from sources (>~1000 km).
Figure 6.18: Time trend comparison for SO4= in
precipitation across the EMEP network.
a) Short distances from sources (<~500 km).
b) Intermediate distance (~500-1000 km).
c) Longer distances from sources (>~1000 km).
For references, please go to https://www.eea.europa.eu/publications/2-9167-057-X/page007.html or scan the QR code.
PDF generated on 14 Dec 2024, 01:56 PM
Engineered by: EEA Web Team
Software updated on 26 September 2023 08:13 from version 23.8.18
Software version: EEA Plone KGS 23.9.14
Document Actions
Share with others