Air quality in Vienna

How healthy is the air in Vienna?

According to the Air Quality Index (AQI), the air quality in Vienna is "moderate" with a 2019 average PM2.5 concentration of 12.3 µg/m³, a value which means that Vienna has missed being categorized as “good” according to the AQI scale by a mere 0.3 µg/m³.

According to the stricter standards of the World Health Organization (WHO), air pollution in Vienna is 23% above the guideline value of 10 µg/m³ for particulate matter (PM2.5) and far behind other European cities such as Berlin, London or Madrid.

Compared to other Austrian cities, Vienna is ranked 11th in the 2019 IQAir ranking with the highest level of air pollution. However, when compared with previous years, Vienna’s air quality has improved. According to the Air Quality Ranking, Vienna is the second-worst Austrian city in terms of fine dust pollution, behind Eisenstadt with 11.3 µg/m³ PM2.5 but ahead of Linz with 13.3 µg/m³ PM2.5.

What causes air pollution in Vienna?

In the city-state of Vienna, three-quarters of particulate matter emissions come from far away, i.e. from pollutant sources are many kilometers outside Vienna. These emissions are carried into the city by the prevailing wind and thus contribute to their air pollution. Several pollutants found at the measuring stations come from the north-east or south-east, while the clean air masses come from the west.

The local sources of pollutants are due to traffic in the city center. Although the particulate matter is not only emitted by the combustion of coal, biomass and waste, but also by certain material processing and the combustion of diesel is a major contributor. In addition, there are emissions from private households and small consumers through heating or other pollutant-emitting behavior.

Does an inversion of the weather conditions in Vienna cause poor air quality?

Normally, the vertical temperature curve becomes lower and lower with increasing altitude, but a corresponding winter weather situation in Vienna can lead to an inversion, i.e. a reversal of the temperature curve. An inversion of weather conditions contributes to the fact that the levels of pollutants in Vienna are higher than without this common weather phenomenon. This happens because the pollutants are "trapped" below the warm layer as a result of the absence of movement between the layers. This phenomenon also partially explains the higher pollution levels experienced during winter in Vienna and its surrounding area. However, geographically speaking, Vienna is not as strongly affected by the inversion of weather conditions as Upper Austria. Moreover, the occurrence and intensity of the inversion of weather conditions seems to have decreased in recent years throughout Austria.

When looking at the available World Air Quality Reports from 2018 and 2019, there is definitely a higher level of pollution during the winter months. A reduction of these values can also be seen over the last few years, but this cannot be attributed exclusively to the reduced occurrence of the inversion of the weather conditions. In addition to the reduction in intensity, various measures have been introduced over the years to reduce Vienna's air pollutants.

Where can the best air quality be found in Vienna?

In 2020, Vienna has been recognized as the world's most habitable city for the third year in a row. However, this ranking is less concerned with air quality but with the quality of life within the city. A closer look at the different districts of Vienna shows that districts with a lower socio-economic development record a higher level of NO₂. However, the socio-economic differences in Vienna are not as pronounced as in other cities, such as Marseille or Dortmund. The Global Liveability Index does not consider air pollution in a comprehensive way and does not include socio-economic disparities within cities such as Vienna.

According to the air quality map published by IQAir .com, air pollution in Vienna can be followed in real time using data provided by measuring stations. These measuring stations are distributed throughout the city center and the suburbs.

When is Vienna's air quality at its best?

During 2019, Vienna managed to achieve the WHO target value for fine dust pollution (PM2.5) for five months. These months were characterized by warmer temperatures. While the higher values in Vienna originate from the colder winter and transition months. In 2018, the PM2.5 concentration was higher than in the previous year at 15.2 μg/m³, as a comparison of the World Air Quality Reports for 2018 and 2019 shows.

What is the air quality in the underground trains in Vienna?

A popular means of public transport in Vienna is the metro or underground rail network. Several studies have shown that it is precisely in this public transport system that air quality is at its worst. A recent study compared the pollution levels of PM10, PM2.5 and PM1 within the Vienna underground system with that outside. In most cases, a significant difference was found between the air quality values inside the underground trains and the values in the surface air. The increased pollution comes from the wear of the tracks, wheels and brake pads within the underground system. However, the general air pollution in the city is influenced more by diesel or petrol-driven passenger transport rather than by an electric underground railway system that gets its electricity from hydroelectric power plants.

The level of air pollution varies depending on the section of the underground railway network. In particular, the underground lines U1 and U3 are expected to have higher levels of air pollution in longer, underground sections. The occasional lack of air conditioning also has a negative impact on air pollution, as shown by the increased levels of particulate matter, as air conditioning systems are an air purification system. Thus, the air quality in the metro network depends on various factors.

What health effects does particulate matter have on people in Vienna?

Although particulate matter levels, like other pollutants, are normally not alarmingly high in Vienna, higher concentrations do occur in winter and are therefore a potential problem for sensitive groups. Sensitivity depends, not only on factors such as health status, age and genetics but also on breathing and sports involvement. The air pollutants measured in Vienna, such as particulate matter, ozone (O₃) and nitric oxides (NO_x), reinforce the effect of pollen in this context. Asthma attacks are also more frequently triggered by high ozone levels, among other respiratory problems. NO_x, like NO₂, increases the likelihood of getting respiratory infections and acts as a precursor gas for PM2.5. SO₂ is also a precursor, but besides causing respiratory infections, SO₂ also causes problems with vision.

Particulate matter is considered the most dangerous pollutant and can be caused by chemical reactions such as burns from the precursor gases. PM2.5 penetrates deep into the respiratory system and damages it. The health effects include coughing, asthma attacks and bronchitis, but also impaired lung function. In addition to the respiratory system, the blood vessels are also damaged by inflammation. It can also lead to increased blood clotting or a higher risk of a heart attack. In children, PM2.5 can limit lung growth and brain function. In the worst-case scenario, exposure to fine particles can lead to death in sensitive groups.

What can be done to reduce air pollution in Vienna?

As approximately 75 per cent of the particulate matter blown in by prevailing winds, it is not only essential to introduce national measures to reduce Vienna's air pollution, but also to have cross-border discussions. This is because measures at an international level have an impact on local air quality, especially when, as in Vienna, the air pollution in question comes from outside the city and partly from outside Austria.

The remaining 25% of Vienna's air pollution, which come from local sources, will be curbed by a package of measures against particulate matter. This package of measures focuses on different sectors that emit pollutants. The package starts with restrictions on winter road maintenance, which includes grit and salt. However, heating systems also reduce emissions of air pollutants through more district heating and similar rises in efficiency. In order to relieve general traffic, the public transport system will be expanded, and speed limits will be maintained. The City of Vienna intends to link public and private transport by means of external Park & Ride car parks. On construction sites, the replacement of various technologies is intended to reduce their emission contribution.

An essential step towards improving air quality is the promotion of electric mobility, both in private and public sectors. The City of Vienna is focusing on new technology that is not reliant on fossil fuels for public and commercial transport towards an improvement of the electromobility infrastructure. Although private procurement is supported to a certain extent, plans of the City of Vienna show a preference towards an increase in the use of bicycles and public transport. However, financial support for electric bicycles was discontinued in 2011, due to lack of supply and demand.

Over the last decade, a significant rise in the use of cycle paths has been observed. Directly related to this, the bicycle infrastructure has also been expanded with more cycle routes and parking spaces. Climate-friendly transport and electric bicycles are also becoming increasingly popular, replacing other environmentally harmful vehicles in Vienna.