Trends in Air Quality in Germany

| BACKGROUND | Trends in Air Quality in Germany IMPRINT Date: October 2009 Cover Photo: M. Isler / www.metair.ch Photos: p. 3 W. Opolka p. 4 www.imageafter.com p. 9 UBA / A. Eggert p.14 www.imageafter.com Publisher: Federal Environment Agency Wörlitzer Platz 1 06844 Dessau-Roßlau www.umweltbundesamt.de Edited by: Federal Environment Agency Section II 4.2 „Air quality assessment“ E-Mail: [email protected] Introduction nitrogen dioxide, ozone pollution is highest Air pollution has markedly decreased in the in rural areas. For some years, a trend last 20 years. Through the introduction of towards higher ozone concentrations has filter and flue-gas denitrification systems in been noticeable in urban areas. power plants and industrial installations; and the use of modern catalysts and fuels, In this booklet we describe trends in air considerably fewer pollutants are today re- pollution with particulates, nitrogen dioxide leased into the atmosphere. EU-wide air qua- and ozone, and explain their connection to lity limit values for sulphur dioxide, carbon changes in air pollutant emissions. monoxide, benzene and lead are no longer exceeded in Germany. Air quality is moni- tored at approx. 650 German measuring stations several times a day. In addition to particulate matter (PM10), nitrogen dioxide (NO2) and ozone (O3), further pollutants such as organic compounds and heavy metals in PM10 are measured. On their way from the emission source (for example, flue or exhaust) to receptor (humans, flora and fauna), pollutant emissions are subject to atmospheric transport and mixing processes as well as chemical reaction. Pollutant concentration in the atmosphere (given, for example, in micro- grams per cubic metre of air) can therefore not be directly deduced from the emitted pollutant quantity (given, for example, in tonnes per year). In principle, however, markedly reduced pollutant emissions give cause to expect that pollutant concentration in the atmosphere will also decrease. We observe, however, that since the beginning of this decade air pollution in Germany through particulates, nitrogen oxide and ozone, despite steadily reduced emissions, no longer shows a clear trend, but is subject rather to mainly interannual fluctuations. The limit values for particulates, which were laid down already in 1999 and are obligatory since 2005, are exceeded in many places in Germany. The same applies for limit values for nitrogen dioxide, which come into force in Germany on 1 January 2010. In urban areas – and, above all, in places affected by heavy traffic – air pollution with particulates and nitrogen dioxide is particularly high. Other than in the case of particulates and 3 Photo: www.imageafter.com Pollution regimes Nitrogen oxides In order to be able to understand spatially NOx is a collective chemical term for nitrogen differentiated trends in air pollution, it is oxides, and comprises nitrogen monoxide necessary to combine concentration values (NO) and nitrogen dioxide (NO2) as summa- obtained at individual air quality measuring tion parameter. Nitrogen oxides are mainly stations in such a way that they characterize emitted as nitrogen monoxide. Nitrogen pollution regimes. The rural background oxide is emitted directly, but also formed regime (green area in the diagram) re- indirectly through chemical reactions in the presents areas in which air quality is largely atmosphere. Internal-combustion engines uninfluenced by local emissions. Stations and combustion processes in industry and in this regime thus represent pollution at energy production plants are the main sour- a regional level, also termed regional back- ces of nitrogen oxides. ground. The urban background regime (yellow area in the diagram) is characteristic Based on the year 1995, NOx emissions of all for areas in which measured pollutant con- source categories decreased by 15% by the centrations can be regarded as typical for year 2000. Up to 2007 they sank by a further air quality in cities. The urban background regime characterizes the pollution that arises Of the nitrogen compounds, gaseous nitrogen di- from urban emissions (road traffic, domestic oxide in ambient air has the greatest significance fuel etc.) and the regional background. Ur- for human health. As a strong oxidizing agent it ban traffic regime stations (red peaks in the leads to inflammation of the respiratory tract and diagram) are typically found on roads with aggravates the irritation effect of other air pollu- heavy traffic. The result is a cumulative con- tants. tribution to urban background pollution that arises from direct emissions of road traffic. The time series curves of air quality shown Schematic representation of pollution regimes: in this booklet reflect the trend over time of average concentrations in the respective pollution regime. Time series curves are therefore not suitable for assessment of compliance or non-compliance with limit values of individual measuring stations. rural urban urban background background traffic 4 1995 2000 2007 2122 kt 1803 kt 1294 kt Energy industries Residential heating systems Manufacturing industries and construction Commercial / institutional and military combustion Road transportation Industrial processes Other transport Agriculture Figure 1: Percentage share of NOx emissions of source categories in the years 1995, 2000 and 2007. 24 percentage points. If one merely considers The effect of a reduction in NOx emissions emissions from road transportation, it has to can be clearly seen in the trend in annual be observed that here the largest reduction, average NOx concentrations: In the period namely 50%, was achieved. Nevertheless, from 1995 to 2007 they declined in the ur- road transportation still accounts for the ban, traffic-affected pollution regime (Figure largest share (44%) of total nitrogen oxide 2, red curve) and in the urban background emissions. (Figure 2, orange curve). µg/m3 250 200 150 100 50 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 rural background urban background urban traffic Figure 2: Trend in annual mean NOx concentration based on the average of measuring stations in the pollution regimes “rural background“, “urban background“ and “urban traffic“ in the period from 1995 to 2007 (with standard deviation). 5 µg/m 3 100 90 80 70 60 50 40 30 20 10 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 rural background urban background urban traffic Figure 3: Trend in annual mean NO2 concentration based on the average of measuring stations in the pollution regimes “rural background“ , “urban background“ and “urban traffic“ in the period from 1995 to 2007 (with standard deviation). The trend in NO2 concentrations in the same weather-related influences. period shows, however, that the marked The range of annual mean values of indivi- reduction in NOx emissions since 1995 is not dual measuring stations can be estimated on reflected in the state of NO2 pollution the basis of the stated standard deviation. At (Figure 3). Since the year 2000, annual mean the same time, it becomes clear that in the NO2 concentrations have hardly changed in urban traffic pollution regime, annual mean urban areas affected by traffic (Figure 3, red concentrations occur that lie considerably curve) and in the urban background (Figure above the limit value of 40 µg/m3, which will 3, orange curve). Recognizable inter-annual be obligatory from 2010. fluctuations are attributable; above all, to 2001 2002 2003 2004 0-5 µg/m3 > 5 µg/m3 >10 µg/m3 >15 µg/m3 2005 2006 2007 2008 >20 µg/m3 >25 µg/m3 >30 µg/m3 >35 µg/m3 >40 µg/m3 >44 µg/m3 >45 µg/m3 >50 µg/m3 >55 µg/m3 >60 µg/m3 Figure 4: Average NO2 pollution in Germany in the years 2001 to 2008 with “spots“. 6 µg/m 3 100 90 80 70 60 50 40 30 20 10 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 rural background urban background urban traffic Figure 5: Trend in annual mean NO concentration based on the average of measuring stations in the pollution regimes “rural background“, “urban background“ and “urban traffic“ in the period 1995 to 2007 (with standard deviation). Average NO2 pollution in Germany demons- Since NO2 concentration in the period under trates a strongly defined slope from urban consideration has shown no reduction since conurbations to rural areas (cf. Figure 4). The 1995, the decline in NOx concentration must share of background pollution amounts to be attributable to declining NO concentra- around 20% in places with high NO2 pol- tion. A declining trend in NO annual mean lution. values since 1995 is easily discernible in the urban background (Figure 5, orange curve) Measurement results obtained in areas influ- and even more so in places affected by heavy enced by roads with heavy traffic are plotted traffic (Figure 5, red curve). as spots, since they characterize local, small-scale pollution and are therefore inappropriate for regional interpolation. Limit values for NO2 and NOX Designation Average period Limit value Point in time, by which the limit value has to be achieved 3 Hourly limit value for the 1 hour 200 µg/m NO2 may 1. January 2010* protection of human health not be exceeded more often than 18 times per calendar year 3 Annual limit value for the Calendar year 40 µg/m NO2 1. January 2010* protection of human health 3 Annual limit value for the Calendar year 30 µg/m NOx 19. July 2001* protection of vegetation * Possible extension of deadline pursuant to EU Directive 2008/50/EC (cf. page 8) 7 Measurements in urban areas affected by Summary: heavy traffic show high NOx concentrations with a high share of NO (Figure 5, red curve), The trend in NO concentrations reflects the since the transport time from tail pipe to the x reduction in NOx emissions. As to NO2, air measuring point is short, compared with the quality has not improved to the extent that reaction time for conversion of NO to NO2.

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