Qualité de l’air à Zurich

What is the air quality in Zurich like?

The city of Zurich had an average fine-dust pollution (PM2.5) of 10.9 µg/m³ in 2019, exactly on the average concentration for the whole of Switzerland, which was also 10.9 µg/m³ in 2019. In comparison to previous years, there is no clear trend towards improved air quality for PM2.5 in Zurich. In 2017 and 2018, the PM2.5 load for Zurich was 10.4 µg/m³ and 11.2 µg/m³ respectively. This means that air pollution in Zurich is around 10% above the World Health Organization (WHO) guideline value of 10 µg/m³ for particulate matter PM2.5. According to the Air Quality Index (AQI), Zurich's annual average air quality has been classified as "good" since 2017.

The level of air pollution in Zurich varies throughout the year. The month of February was the month with the worst air quality, measuring 20.9 µg/m³ of average PM2.5, and was above the doubled WHO guideline value. In September 2019, however, air quality was only 7.2 µg/m³, thus meeting WHO recommendations. Particularly in the winter months and on special public holidays, such as the Swiss National Day on 1 August and New Year's Day, when there is a significant use of fireworks, peak levels of particulate matter are often reached. Due to these peaks, which are visible on the city map, in 2019 "moderate" PM2.5 values were reached, which can pose health challenges for sensitive groups, such as asthmatics, in Zurich on these days.

How does air pollution in Zurich compare to other cities?

If you want to compare the annual average value of PM2.5 in Zurich (10.9 µg/m³) with other cities in Switzerland, you can easily do so on the 2019 city rankings. Here you can see that although the Swiss capital Bern had the same average PM2.5 particulate matter pollution in 2019 as Zurich, in 2018 and 2017 it was 14% and 30% higher than Zurich's values.

With the data from the 2019 World Air Quality Report it is also possible to compare Zurich's air quality values internationally. For example, Beijing, the capital of China, has almost four times higher particulate matter pollution with 42.1 µg/m³ PM2.5. Tokyo, Japan, on the other hand, is only slightly above the Zurich PM2.5 value of 11.7 µg/m³. Sydney in Australia is better than Zurich at 10.1 µg/m³. In a European comparison, Zurich's air quality is in good midfield. For example, on an annual average, Berlin has slightly better air and Vienna has slightly worse air than Zurich.

Is the air in Zurich getting better or worse?

Since 1986 it has been clear that air quality in Zurich has been improving significantly. This has been achieved through various measures and traffic restrictions introduced in 1986. At that time, the health authority adopted a concept to reduce air pollution. Measuring stations for nitrogen oxides (NO_x), nitrogen dioxide (NO₂), particulate matter (PM10 and/or PM2.5), ozone (O₃), carbon monoxide (CO) and sulphur dioxide (SO₂) were installed throughout the city. These stations are still in use today.¹

In recent years, Zurich's air quality has remained relatively constant. The values are kept in check by various measures and thus do not exceed a "moderate" value on the air quality index (German: LQI, English: AQI), but regularly exceed the recommendations of the World Health Organization (WHO).

Where can you see real-time air quality for Zurich?

The AirVisual app and the IQAir website display Zurich's air quality in virtually real time. It also provides an air quality forecast for the next 7 days. This is calculated from weather data, air quality data from public and private measuring stations and traffic data. Through regular monitoring, it is possible for sensitive people to adapt their activities to the current air quality and take appropriate precautions.

In addition, on the real-time map at the top of this website, one can observe air quality in Zurich and the surrounding area at local and regional level.

What causes air pollution in Zurich?

The air pollution in the city of Zurich is mainly due to the heavy traffic of cars and heavy goods vehicles, as well as private wood firing in winter. Air pollution has already cost the city of Zurich approximately 296 million Swiss francs in 2010. Traffic contributed to this figure with a share of about 45%, closely followed by 30% due to industry with construction machinery and industrial and commercial processes. Around 20% of the costs caused by air pollutants in Zurich are attributable to wood combustion in private households.²

The main polluter, traffic, is mainly dominated by motorized road traffic. Half of the NO_x emissions and around 33% of the particulate matter are attributable to road traffic. Rail transport also contributes partly to transport emissions. Abrasion during use, especially of iron, causes the majority of PM10 emissions into Zurich's air. Although passenger and cargo ships account for a small proportion of the pollution in Switzerland as a whole, shipping on Lake Zurich can cause significant local pollution of soot particles. As passenger ships are mostly powered by diesel, they are obliged to use particle filters to reduce emissions of the pollutants.³

Zurich Airport, which is used frequently, is not located in the city of Zurich, but in the neighboring municipality of Kloten. Due to the immediate vicinity, slightly higher measured values of the pollutants can be seen on the real-time map of Zurich and the surrounding area at this border of Zurich. After a few kilometers, however, the airport-related emissions are masked by local emissions, such as those from ground-level traffic, and are therefore no longer measurable.⁴

Why is particulate matter so dangerous in Zurich?

The danger of PM2.5 is that this fine dust consists of solid and liquid air pollutants that are so small that they can pass almost unhindered through the airways to the alveoli and settle there. This deposit causes damage that makes the body more susceptible to infectious diseases. An excess of particulate matter in the respiratory system can cause irritation, asthma and cardiovascular disease. The impairment of lung function caused by particulate matter pollution triggers further cardiovascular diseases. Particularly harmful are soot particles, which are carcinogenic and are also responsible for prenatal genetic damage.⁵

Other air pollutants, such as nitrogen oxides (NO_x), can also damage the respiratory system. Inhalation of NO_x can lead to NO₂ compounds in the blood, which are considered extremely toxic. Another pollutant in Zurich is ozone (O₃). This not only affects human health through irritation of the respiratory tract and the visual organ, but also that of plants. The harmfulness of ozone is due to the high oxidation power and low water solubility of ozone.⁶

What is being done in Zurich to improve air quality?

The City of Zurich is following the action plan of the Canton of Zurich. To combat winter smog due to inversion weather conditions, measures have been established at cantonal level which also affect the city of Zurich. There are 3 stages of the SMOG Ordinance, which come into force when the measured particulate matter value PM10 is above the limit value of 75 µg/m³. In the first stage, with particulate matter above 75 µg/m³, the population is informed and encouraged to use public transport to reduce particulate matter. If the particulate matter value of 100 µg/m³ is exceeded, a speed limit on the motorway will be introduced after consultation with the neighboring cantons in order to reduce the amount of particulate matter released at higher speeds. Open fires as well as stoves without a particle filter may not be used when exceeding these fine dust values. If the particulate matter levels exceed 150 µg/m³, the ban on diesel-powered machines will also come into force. These measures will be lifted again when the particulate matter level falls below 50 µg/m³ again.⁷

As wood combustion is a significant contributor to air pollution in Zurich, the air pollution control measures plan sets a certain standard for the entire canton of Zurich in terms of thermal output. If necessary, these requirements are to be followed up by refurbishment of the furnaces in order to reduce particulate matter pollution in Zurich. Also, only certain (wood) fuels are to be used and the chimneys are to have a certain height and width at the mouth. The plan of measures also considers the source of emissions from industry and commerce. In this respect, the measures focus mainly on the construction machinery and equipment used, which are mainly diesel-powered. However, the limit values for dust emissions have also been revised.⁸ Further industrial combustion releases pollutants into the Zurich air from combustion plants using oil, gas and wood. In order to improve these values in accordance with the Ordinance on Air Pollution Control, the Canton of Zurich is attempting to make the polluting technologies more environmentally friendly and thus comply with the new emission regulations. However, the municipalities themselves are responsible for monitoring compliance with the cantonal limits.^9,10

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[1] Umwelt- und Gesundheitsschutz Zürich UGZ. (2016). Luftbilanz 2016 Resultate der flächendeckenden Messkampagne. Stadt Zürich.
[2] Quellen der Luftbelastung - Stadt Zürich. (2020, June 3). Stadt Zürich.
[3] Verkehr - Stadt Zürich. (2019, November 6). Stadt Zürich.
[4] Ebd.
[5] Umwelt- und Gesundheitsschutz Zürich UGZ. (2016). Luftbilanz 2016 Resultate der flächendeckenden Messkampagne. Stadt Zürich.
[6] Ebd.
[7] Amt für Abfall, Wasser, Energie und Luft – Abteilung Luft, Klima und Strahlung. (o. J.). Massnahmen bei Smog. Kanton Zürich.
[8] Amt für Abfall, Wasser, Energie und Luft. (2016). Massnahmenplan Luftreinhaltung. Kanton Zürich.
[9] Ebd.
[10] Baudirektion Zürich. (2018, June). Nebenbestimmungen für Feuerungsbewilligungen. Kanton Zürich.