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Air pollution - State & Impacts
What are the state and impacts?
PM10
Despite substantial progress in reducing emissions especially during the 1980s, in recent years the limit value for the daily mean of PM10 of Directive 2008/50/EC (50 µg/m³ not to be exceeded more than 35 times per year) was exceeded in several provincial capitals and small towns. The only larger Austrian town with PM10 levels below the limit value in most years is Salzburg. The sources that are mainly responsible include road transport, residential heating using solid fuels, the industrial sector and the building industry, as well as agriculture in rural areas and, to some extent, long-distance transport.
Figure 1 shows the average concentration and number of exceedances of all urban and suburban monitoring sites in Austria from 2001 to 2008. Especially in 2007 and 2008 the levels were rather low. This was on the one hand due to favourable meteorological conditions, on the other hand a result of national and international abatement measures.
Figure 2 shows the number of exceedances of the daily mean limit value at selected highly polluted sites in urban areas. The city experiencing the highest levels is Graz, which is caused by rather unfavourable dispersion conditions in an alpine basin.
NO2
The limit value for the annual mean of nitrogen dioxide of Directive 2008/50/EC (40 µg/m³) is exceeded in Austria occasionally, especially close to roads with heavy traffic. The main source of NOx emissions in urban areas is traffic (see also Figure 13). Figure 3 shows the average annual mean concentrations of NO2 in urban and suburban monitoring sites from 1993 to 2008. Until the year 2000, NO2 levels were decreasing whereas in the years afterwards no statistical significant trend can be observed. In the year 2008, NO2 concentrations were on the same level as in the year 2000, despite a reduction of NOx emissions. At highly polluted sites, an increase in NO2 concentrations was also observed (Figure 4). This is caused by an increase in primary NO2 emissions due to exhaust after-treatment systems of diesel passenger cars.
Ozone
The target value for the protection of human health of Directive 2008/50/EC (120 μg/m³ not to be exceeded on more than 25 days per calendar year averaged over three years) was exceeded at 54% of all monitoring sites in Austria between 2006 and 2008.
No significant trend of the exceedances can be observed. Averaged over all monitoring sites, a decrease of 0.4 days per year was found between 1992 and 2008.
To reduce ozone levels, substantial reductions of emissions of the ozone precursor substances VOC and NOx are necessary in Austria as well as in other countries in central Europe. NOx emissions are currently above the NEC limits for 2010.
The target value for the protection of the vegetation (AOT401 of 18,000 µg/(m³.h)), averaged over five years) of Directive 2008/50/EG was exceeded at 60% of all monitoring sites in Austria between 2004 and 2008. The long-term objective for the protection of vegetation (AOT40 of 6,000 µg/(m³.h)) was exceeded at all stations save one, which is situated close to a highway due to NO titration.
(1 AOT40: means the sum of the difference between hourly concentrations greater than 80 µg/m³ (= 40 parts per billion) and 80 µg/m³ over a given period using only the one-hour values measured between 8.00 and 20.00 Central European Time (CET) each day.)
No significant trend of the AOT40 levels since 1992 can be observed. Averaged over all monitoring sites, an increase of 200 µg/(m³.h) per year has been found.
Acidification:
Acidification can lead to longterm damage in the structure and functioning of ecosystems. To estimate the ecosystem area at risk, the Critical Loads concept was developed within the UNECE Convention on Long-range Transboundary Air Pollution. Critical Loads for acidification are projected to be exceeded at four out of 496 sites in 2010. This corresponds to about 0.6% of the overall modelled forest ecosystems. All exceedances occur in the northern part of Austria ("Böhmische Masse" which is characterised by a low buffering capacity of acidifying substances). The exceedances are caused by both sulphur and nitrogen deposition (Umweltbundesamt 2008).
Critical Loads: A quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge' (Nilsson and Grennfelt 1988).
Eutrophication:
Deposition of nitrogen can lead to eutrophication which changes the biodiversity of an ecosystem. Critical Loads for eutrophying nitrogen deposition are projected to be exceeded at about 94% of the forest area. The highest exceedances occur north of the Alps and in the eastern part of Austria, reflecting high nitrogen deposition in these areas (Figure 7).
For semi-natural vegetation, Critical Loads are based on expert estimates. These empirical Critical Loads for eutrophying nitrogen for semi-natural vegetation are exceeded at 31% of the ecosystem area. The percentage of exceedance per ecosystem is shown in Figure 8. Figure 9 shows the exceedance of empirical critical loads.
