Fine particles

On 11 April 2018, the Federal Council approved amendments to the Ordinance on Air Pollution Control, in particular the setting of an ambient limit value for PM2.5. The annual mean concentration limit of 10 µg/m3 is in line with the recommendations of the World Health Organization WHO from 2005 and supplements the existing limits for PM10. In 2021, the WHO lowered its guideline values for several air pollutants, including particulate matter PM2.5, based on new scientific evidence. The Federal Commission for Air Hygiene recommends amending the Ordinance on Air Pollution Control to align the ambient air quality standards with the WHO's guideline values 2021. The pollution of the air with these tiny dust particles has a major impact on human health and is a challenge for Swiss clean air policy.

Particulate matter (PM10) is a complex mixture of the following:

  • Primary particles, which are emitted directly as a result of combustion processes (e.g. diesel engines and wood-fired heating systems), the abrasion of tyres, brakes and road surfaces, and resuspension;
  • Secondary particles, which are formed in the atmosphere from gaseous precursors (sulphur dioxide, nitrogen oxides, ammonia and volatile organic compounds).

Serious effects on public health

PM10 and PM2.5 are the terms used to designate particles with a diameter measuring less than 10 thousandths, respectively 2.5 thousandths, of a millimetre, which can penetrate the finest branches of the bronchial tree and sometimes pass into the lymphatic system and the bloodstream. Because of their fissured structure, these particles offer an ideal surface for the attachment of other toxic substances.
This cocktail of pollutants comprises a wide range of compounds, some of them carcinogenic such as soot. It causes local inflammation in the respiratory tract and may thus produce serious effects on health:

  •  cough, respiratory distress, bronchitis and asthma attacks in children and adults
  •  respiratory and cardiovascular disease, possibly necessitating hospitalization
  •  lung cancer; and premature deaths.


Further effective measures required

Cities and built-up areas close to traffic are still exposed to excessive levels of particulate matter particularly in the winter months. To ensure that the limits currently specified for particulate matter are complied with, current levels of PM10 emissions in Switzerland need to be reduced by around 50%, and a similar reduction is required for emissions of precursor gases.

This goal can only be achieved by continuing to tighten air pollution control requirements and adopting a variety of measures. These measures must be implemented locally, nationally and internationally. To that end, the Swiss Federal Council adopted an action plan on particulate matter in 2006 designed to reduce emissions from all the principal sources. Measures include, for example, fitting particulate filters to diesel engines, and applying stricter emission limit values to wood-fired heating systems.

Air pollution: Current data and evolution

In conurbations and areas of high traffic density, annual average concentrations of fine particles still sometimes exceed the legal limits, and 24-hour limits are also exceeded.


Further information

Last modification 28.03.2024

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