Air pollution - State and impacts (Germany)
- Air pollution
The monitoring of air quality in Germany is regulated by the Federal Emission Control Act (BImSchG). Networks of the federal Länder monitor the quality of the air comprehensively, while the German Federal Environment Agency (Umweltbundesamt, UBA) also operates measuring stations – so-called background stations – which collect concentration and deposition data for the investigation of widely dispersed air pollution in rural areas. These data provide the basis for reporting on an international level. The data from the Länder monitoring networks and the UBA provide the foundation for the presentation of the country’s air quality.
Until the start of the 1990s, the airborne pollutant sulphur dioxide (SO2) was still one of the leading components of atmospheric pollution in Germany. The successful reduction of SO2 pollution by emission-reducing measures, above all from power stations and industrial plants, has led to the situation in which air pollutants from the transport sector increasingly predominate. These include above all particulates (PM10) and nitrogen dioxide (NO2), which are at the forefront of public concern in view of their high airborne concentrations and the resulting health-related risks. However, the secondary airborne pollutant ozone (O3), which is generated from volatile organic compounds (VOC) and oxides of nitrogen under the influence of intensive solar radiation, also plays a not insignificant role. In contrast, extensive emission-reducing measures have significantly reduced atmospheric pollution by benzene (CH6). The limit value for CH6 for the protection of human health, which comes into effect in 2010, is already being met with few exceptions in conurbations and cities.
Air pollution and human health
Traffic-related pollutant emissions are among the main sources of air pollution in the conurbations of the industrialised countries. The major pollutants emitted by motor vehicles in their exhaust gases include nitrogen oxides (NOx) and volatile organic compounds which are essential precursors of ground-level ozone, and particulates.
The limit values for the airborne pollutant NO2 have only been mandatory in Germany since 1 January 2010. It is already clear that the annual limit value of NO2 for the protection of human health (40 µg/m³), cannot be met at many urban air measurement points – readings taken at more than half of the urban traffic-oriented air measurement stations indicate that this value is being exceeded. In the urban background environment, only a few measurement stations are at present exceeding the annual limit value of NO2. The 1-hour limit value for NO2 that takes effect from 2010 – according to which 200 µg/m³ must not be exceeded more often than 18 times per year– is mostly being met at the urban background measurement points. In recent years, the 1-hour limit value was exceeded mainly on roads with heavy traffic and steep lateral walls. In 2005, for example, the measurement point at Neckartor in Stuttgart recorded a total of 848 hours in which the 1-hour limit value for NO2 was exceeded.
The concentration of ground-level ozone has been continuously monitored for decades. In 2007 data were collected by the Federal Government and the Länder at 282 measurement stations.
Europe-wide target values to be met from 2010 and 2020, respectively, as well as a public information threshold and an alarm threshold for short-term peak loads, were adopted into German law with the 33rd Regulation under the Federal Emission Control Act.
The number of ozone values in excess of the information threshold, 180 µg/m³ and the alarm threshold, 240 µg/m³, fluctuates from year to year because of annually fluctuating weather conditions in the summer.
Compared with 1990, emissions of ozone precursors, NOx and VOC, had decreased by 2006 by around 51 % and 64 % respectively. The lower emissions of these had already led to a reduction in ozone peak values in the 1990s. An exceptionally long-lasting weather situation was observed in the summer of 2003, which favoured the formation of ozone, making the ozone summer of 2003 a special case.
A target value for ozone has been set from 2010 onwards with a view to the protection of human health: 120 µg/m³ as an 8-hour mean should not be exceeded on more than 25 days per calendar year, averaged over three years. Averaging is carried out in order to make allowance for the meteorological variability of individual years over a long-term observation period. The highest numbers of days on which the target is exceeded are recorded at rural and suburban background stations, i.e. at some distance from the sources of the precursor substances. In the past few years, the aspired target value was exceeded in many parts of Germany.
By 2020, the 8-hour mean value of 120 µg/m³ during a calendar year should no longer be exceeded. In 2007, this value was still being exceeded almost everywhere.
In order to be able to exclude risks to health in the future, emissions of the precursors from transport and from the use of solvents in industry, business and private households must be further reduced. The Federal Government reviewed its National Programme for the Reduction of Ozone dating from 2002 with this in mind and published an updated version in 2007. The programme contains measures with medium- and long-term effects. The aim is to reduce emissions of NOx and VOC from mobile and stationary sources.
Particulate air pollution
The Europe-wide limit values for particulate matter (PM10) that have been in force since 2005 were adopted into German law with the 22nd Regulation under the Federal Emission Control Act. The Regulation stipulates the following limit values for the protection of human health:
The PM10 annual mean value must not exceed 40 µg/m³.
The PM10 daily mean value must not exceed 50 µg/m³ on more than 35 days in a calendar year.
Since 2000, the monitoring networks of the Länder have been carrying out comprehensive PM10 measurements. The monitoring network density is particularly high in conurbations as the high number and density of emission sources – in addition to the transport sector, for example domestic heating installations, commercial enterprises and industrial plants – leads to a higher PM10 concentration in conurbations than in the surrounding countryside. Particularly high concentrations are recorded at traffic-oriented measurement stations, partly because of high traffic-related emissions such as diesel soot, tyre abrasion particles and dust suspended in the air. It has been established since 2000 that PM10 pollution is not verifiably falling in Germany, but that it merely fluctuates from year to year depending on the weather conditions.
There are many places in conurbations that overshoot the permissible number of days on which daily mean value may be exceeded. In 2007, 23 % of the urban traffic-oriented stations recorded more than 35 days on which the limits were exceeded. The high number of days of exceedance in 2003 can be attributed to episodes of high PM10 pollution all over Germany. At the urban background stations – locations that are more remote from traffic emissions – exceedance of the daily mean PM10 value is less frequent; in 2007, it was never exceeded at any urban background station. The PM10 limit value for the annual mean is rarely exceeded and if so exclusively at locations with a heavy traffic load.
Air pollution and environment
Whereas airborne nitrogen deposition from traffic and industry has decreased in recent years, deposition of ammonia gas and ammonium from animal husbandry has remained at a high level.
The improvements in respect of eutrophication that have been achieved through national and international air pollution control measures are poor in comparison to those achieved for acidifying depositions. Critical loads for eutrophying nitrogen are still being exceeded over almost the entire area of fragile ecosystems in Germany. In parts of the northwest, where intensive animal husbandry takes place on ecologically sensitive land and the deposition of nitrogen - predominantly ammonium – is especially high, the critical loads are exceeded particularly seriously.
The proportion of areas with very high exceedances fell between 1990 and 1995, but no further reduction was noted thereafter. The greatest proportion of the observed areas exhibit at least distinct exceedances. The classes of critical load exceedance used in the chart can be defined as follows:
no exceedance: zero kg ha-1 a-1
low exceedance: more than zero to 10 kg ha-1 a-1,
distinct exceedance: more than 10 to 30 kg ha-1 a-1,
very high exceedance: more than 30 kg ha-1 a-1 above the critical load.
Furthermore, the almost nationwide eutrophication of semi-natural ecosystems must be expected to continue in the next few years as a consequence of the only marginally decreasing emissions of ammonia gas. There is thus a significant need for action to reduce diffuse nitrogen emissions.