Chapter 05 Vienna’s Air
» Current Status
» Air Quality Measurement Network
» Air Pollutant Balance 2005
» Urban Air Initiative Vienna (ULI)
A great many measures are in place to increase public awareness of air pollution control in Vienna
Vienna’s reputation as a city with one of the highest standards of living in the world is due not least of all to the
excellent quality of its air. Emission reductions on a sometimes considerable scale have been achieved in the last
two decades with long-ranging and targeted measures. As a result, air quality in Vienna and the surrounding
areas has been significantly improved. Despite this, air pollution remains a serious problem, not least of all due to
the sharp increases in traffic levels.
The Requirements of the Air Pollution Control Act
Solutions for Airborne Dust, PM10, NO2 and Ozone
The Air Pollution Control Act, which lays down universally valid pollutant limit values, was passed in order to
comply with a corresponding EU directive. The provisions of the Air Pollution Control Act require that in addition to
those components previously measured, sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO),
airborne dust (TSP) and ozone (O3), the pollutant components lead and benzene in airborne dust must also be
recorded. Moreover, deposition measurements for dust precipitation and its components lead and cadmium must
also be carried out. The amendment passed in summer 2001 included the airborne dust components PM10
(particles in the atmosphere with a diameter of less than ten micrometers) and introduced target values for PM10
and nitrogen dioxide. As the amendment to the Air Pollution Control Act also defined alarm thresholds for sulphur
dioxide and nitrogen dioxide, the previous Smog Alarm Act was repealed. The data obtained from several years
of Air Pollution Control Act measurements show that airborne dust, PM10, NO2 and ozone constitute the main
pollutants. Fortunately, the other pollutant components fall below the valid limit values for human health, in some
cases quite significantly.
Status Survey on Occasions When Threshold Values are Exceeded
If the pollutant thresholds contained in the Air Pollution Control Act are exceeded, this is documented in the
monthly and annual reports. If the upper limit is not exceeded because of an accident or temporary, non-recurring
load, a status survey must be carried out which must include a description of the pollutant input and emission
situation as well as the meteorological conditions.
Moreover, it must be established which specific corrective measures must be taken and in which area. A
catalogue with emission-reducing measures for the reclamation area can then be issued by decree. Possible
measures might include, for example, emission limitations for plant facilities, traffic restrictions and restrictions on
the use and manufacture of specific substances.
Air Quality Measurement Network
The quality of Vienna’s air is continuously monitored by a comprehensive pollutant measurement network with 17
stationary measurement stations and a mobile air measurement bus. Almost all measurement stations are
housed in modern measuring containers. Some of these were placed in locations which are frequented by heavy
traffic in order to ensure a particularly critical description of the air quality.
What Is Measured and Where
All measurement stations are equipped with measuring apparatus for nitrogen oxides. In addition, sulphur dioxide
is measured at ten locations, and carbon monoxide at four locations which are exposed to heavy traffic. At two
further locations which are exposed to heavy traffic benzene values are regularly measured. Five stations also
have ozone measuring apparatus. Lead and cadmium levels in dust precipitation are measured at two other
measurement stations (Laaer Wald and the A4 Motorway). Meteorological sensors also measure wind speed,
wind direction, air temperature, air pressure and humidity at selected locations.
EU-Compliant Data Collection
The air samples are taken in compliance with the regulations laid down by the EU and the Air Pollution Control
Act in order to obtain information about the quality of air in all locations used by urban residents. This approach
means that the data obtained is comparable not only throughout Austria, but throughout the EU. A special
environmental mobile measuring unit for the flexible measurement of the pollutant components sulphur dioxide,
nitrogen oxides, airborne dust, PM10, carbon monoxide and ozone is also used to control air pollution abatement.
The mobile measuring unit – like the other 17 stationary measurement stations – is monitored by a central
computer and transmits the data directly to the measurement centre of the Municipal Department of
Environmental Protection (MA 22) around the clock.
Changes to Pollutant Monitoring
In late 2004 the threshold value for airborne dust was abolished, as a result of which the airborne dust
measurement stations still in operation had to be converted to PM10 at the beginning of 2005. The reduction in
the number of SO2 measurement stations which had been started in 2003 was continued in 2004. Sustained low
SO2 readings mean that a much less dense network of measurement stations is perfectly adequate. At the same
time, the installation of new stations for the measurement of fine dust which had been initiated in 2002 was
continued in 2004 and 2005.
What is measured where (as of 1 Jan. 2006)
Overview of the input and deposition measurements in accordance with the Air Pollution Control Act of the Vienna
Air Quality Measurement Network
Measurement Station Components Measured
SO2 NO2 CO PM10, PM2.5 O3 Benzene
Stephansplatz X X X
Taborstraße X X PM10
Währinger Gürtel X PM10, PM2.5
Belgradplatz X PM10
Laaerberg X PM10 X
Kaiserebersdorf X X PM10
Rinnböckstraße X X X PM10 X
Gaudenzdorf X X PM10
Hietzinger Kai X X X
Kendlerstraße X PM10
Schafbergbad X X PM10
Hermannskogel X X X
Hohe Warte X X X
Gerichtsgasse X X PM10
Lobau X X PM10 X
Stadlau X X PM10
Liesing X X PM10
Laaer Wald Dust precipitation, lead and cadmium in dust precipitation
Ostautobahn Dust precipitation, lead and cadmium in dust precipitation
Air Pollutant Balance 2005
Air quality in Vienna is mainly impaired by emissions of pollutants from the combustion of fossil fuels, vehicle
traffic and emissions from trade and industry. For geographic and climatic reasons, but also because of the very
small percentage of industrial companies producing high levels of pollutant emissions, conditions in Vienna are
generally very favourable.
Nevertheless, emissions of substances such as nitrogen oxides and fine dust still harm the quality of Vienna’s air.
As an urban conurbation, Vienna is exposed not only to its own emissions, but also occasionally to extensive
migrations of pollutants from Germany, the Czech Republic, Slovakia and Hungary. The development of ground-
level ozone also influences the quality of the city's air.
Considerable Reductions in SO2 Levels in Recent Decades
Since the 1970s there has been a dramatic reduction of pollutant loads in Vienna. Up until the 1990s the decline
was attributable to a significant reduction in sulphur dioxide (SO2) emissions both in Vienna and throughout
Austria (chimney gas cleaning facilities, fuel conversion to natural gas, gradual reduction of the sulphur content in
fuel, reduction of domestic heating emissions due to the expansion of district heating systems).
There is a strong link between sulphur dioxide levels and atmospheric influences. Higher concentrations over
wider areas always occur in winter during sustained periods of high barometric pressure. Under these conditions,
SO2 can also be transported over long distances.
The reduction of SO2 emissions in neighbouring states to the east and north of Austria since the 1990s has,
therefore, also resulted in a further decline of sulphur dioxide levels in Vienna. In the summer months, readings
are so low that they are barely above the detectable limit.
Fine Dust – PM10
Readings for the fine dust component PM10, which have been gathered since 2002, sometimes exceed the
defined limit value of an average 50 microgrammes per cubic meter per day, not only throughout the entire city of
Vienna, but also in rural areas and in other European conurbations.
The limit value defined as the annual average value was also exceeded in locations close to roads. The following
chart gives an overview of the results of PM10 monitoring in Vienna.
Due to the relatively brief recording period of four years and the strong link with winter weather, it is virtually
impossible to predict the future development of PM10 pollution in Vienna. During the course of a year, the highest
concentrations are generally observed during the winter months. At this time of the year, the long-distance
transport of pollutants and frequent inversion weather conditions, which contribute to poor pollutant dilution, are
responsible for the vast majority of cases in which limit values are exceeded.
In order to help reduce fine dust loads in the urban area, the city of Vienna in 2005 fitted all diesel-fuelled
municipal vehicles with particle filters where this was technically feasible.
Periods of frost with heavy snowfall possibly interrupted by warm weather spells result in damage to Vienna's
road network. The repair of these potholes not only serves the interests of road safety, it is also important for
reducing dust levels in the city as grit, tyre abrasion and other types of road dust accumulate in the potholes. In
spring 2005 some 40,000 cases of frost damage were repaired.
The Main Reasons for High PM10 Values
Existing studies highlight the most important sources of fine dust in Vienna: road traffic emissions (e.g. whirled
road dust, exhaust fumes, tyre, brake and road abrasion). In some districts, commercial and industrial emissions
and dust from untarmaced road surfaces also play a role. Additional sources for the development of particles of
fine dust are gaseous precursor substances such as nitrogen oxides, sulphur dioxide and ammoniac which are
transported over long distances. Thus, it is not only regional, but also supra-regional sources which contribute to
fine dust pollution in Vienna. Seventy five per cent of pollutant loads in Vienna are caused by polluters from
outside the city. Emissions in Vienna, which are therefore responsible for an average 25 per cent of the pollutant
load, fall into the categories shown in the chart “Percentage of PM10 Emissions in Vienna by Polluter”.
Traffic as the Main Cause of NO2
In addition to their direct impact as an air pollutant, nitrogen oxides are also precursor substances of ozone and
fine dust. In Vienna, road traffic is the main cause of nitrogen dioxide emissions, accounting for approximately 50
per cent of the total. This was confirmed by the NO2-Status Survey published in 2005 (available online at:
There is a great deal of evidence to suggest that concentrations of nitrogen dioxide also depend on the weather
and air temperature. Lower temperatures combined with inversion weather result in increased NO2 loads.
In terms of pollution trends, it should be noted that the successive slight decline of annual NO2 loads in the years
up to 2001 was unfortunately not continued in 2002 and 2003. On the contrary, since the end of 2001 the average
load has once more risen to the 1998 level. Without a doubt, this development was partly due to the unusual
meteorological conditions in 2003 and rising volumes of traffic.
A sharp rise in NO2 loads has been observed at measurement stations located very close to roads in the past
three years. One reason for this is the significant increase in the number of diesel vehicles, which have a
considerably higher level of NO2 in their exhaust. It is to be expected that the limit values will be continuously
exceeded in future.
A Frequent Problem in Summer: Ozone (O3)
Ground-level ozone is not emitted directly. During high-pressure summer weather – and in conditions of high
temperatures, or calm and dry air – this pollutant develops mainly as a result of nitrogen oxides and carbon
monoxides. The vast majority of the substances which precede the formation of ozone are generated by traffic
emissions, but also by other combustion processes in industry, commerce and households.
On several occasions in recent years and under appropriate weather conditions, the “information threshold” (prior
to 1 July 2003, the “early warning stage”) has also been reached. Due to the strong link between weather
conditions and ozone levels it is difficult to predict future trends. The annual average ozone values (see the figure
on page 46) correlate fairly well with the annual average air temperature. However, this does not alone suffice to
explain the increased ozone level.
In 2002 the early warning level was not reached a single time. In contrast, ozone levels in summer 2003 were
particularly high, with ozone concentrations in northern Vienna reaching the early warning stage by the middle of
On 1 July 2003 the threshold values for warnings were adjusted to conform to European Union directives and
significantly tightened. Parallel to this, the exceptional summer of 2003 produced record-breaking ozone levels.
Ultimately, not only was a peak value of 259 microgrammes per cubic meter recorded, the year also saw the
greatest number of days when limit values were exceeded.
In addition, the alarm threshold also had to be declared on four days. Compared to the record year 2003, 2004
was an average ozone year. In terms of peak loads, the figures for 2004 were in fact better than those of the
previous 12 years.
Ozone levels in 2005 were significantly below average. As a result, the information threshold was only declared
eight times – although the alarm treshold was reached once This ozone alarm threshold had to be declared
because of a brief peak in Schwechat.
Ozone Projection Model
The City of Vienna has been working intensively with the provinces of Lower Austria and Burgenland to develop
measures to reduce the ozone burden in the Pannonian region. However, in order to reduce peak ozone loads in
practice, measures need to be implemented one or two days in advance. Vienna is therefore working on an ozone
projection model which is currently undergoing two years of trials. The model system for predicting ozone levels
on the basis of the regional weather forecast was compiled in co-operation with the Central Institute for
Meteorology and Geodynamics (ZAMG), the Institute of Meteorology at the University of Natural Resources and
Applied Life Sciences Vienna (BOKU-Met), and when operational should draw up a two-day air pollution forecast
for north east Austria at short notice.
All ozone alarm reports issued since 1 July 2003 are available online under the following link:
Vienna air quality information:
Leaflets, brochures, hotlines, links
• To request brochures and leaflets, and for enquiries: Environmental hotline, Tel.: 4000/88220
• Recorded “Ozonix” – 24-hour air quality information service with hourly updates,
• Current air quality, daily, monthly and annual reports, status surveys, ozone warning service and ozone alarm
• Air quality information from the whole of Austria www.umweltbundesamt.at/umweltschutz/luft
Further information is also available from the ORF teletext service, page 782, the cable TV information channels
and in the cable network.
Urban Air Initiative Vienna (ULI)
For a number of years, the responsible officials of the city of Vienna have been working to develop an air quality
management system which takes account of all environmental, technical and economic considerations. The
Urban Air Initiative Vienna (ULI) was launched in spring 2005 by the city with the aim of reinforcing this policy.
Officials hope that implementation of the ULI will make a major contribution to compliance with the “air quality
limit values” laid down by the Air Pollution Control Act and also improve the quality of air in Vienna and the
Specifically, an evaluation of possible measures which can be expected to lead to a long-term reduction of
pollution levels caused by fine dust, ozone and nitrogen oxides is to be drawn up, as are emission scenarios and
plans for the expansion of networks. A research programme will also be established.
Responsibility for managing the project rests with the Municipal Department for Environmental Protection (MA 22)
which set up five project groups (stationary polluters, traffic, urban planning, legal instruments and construction) to
carry out the work.
Results to Date
As a first result, four measures were drawn up for the decree issued by the Mayor of Vienna pursuant to the Air
Pollution Control Act (Air Pollution Control Act, Catalogue of Measures 2005). As the Act in its current form leaves
little scope for local measures, an accompanying package of measures which can be implemented in the city´s
area of jurisdiction was drawn up by the ULI working groups. This package comprises 18 measures covering plant
facilities, traffic and urban planning. Parallel to these measures which can be implemented in the city´s area of
jurisdiction at short notice, work was also started in the field of public relations which found its way into an
information campaign on air pollution/fine dust and publication of a fine dust information brochure. Furthermore,
work is progressing on effective long-range measures within the framework of the ULI project. As the predominant
share of the pollution load in Vienna is "imported" in the case of fine dust, for example, one of the main areas of
emphasis will be supra-regional and international co-operation. Overall, Vienna’s air quality strategy goes beyond
what is legally necessary and opens up longer-term perspectives for reducing air pollutants.
In future a research programme is to be implemented within the framework of Vienna's air quality strategy, which
will deal with unresolved issues relating to the reduction of pollutants.
With contributions from:
MA 22 – Environmental Protection