01 November 2008

In Switzerland, around three million people are affected by too high a level of particulate matter in the air. Particularly damaging are the minute particles that penetrate deep into the lungs. These come primarily from traffic, the manufacturing industry and wood-burning heaters.

Fine particles, also also known as PM10, is a term used for particles of 10 micrometers (thousandths of a millimetre) or less. When winter atmospheric inversion occurs in particular, major conurbations regularly experience fine particulate pollution which goes far beyond the maximum levels recommended by the World Health Organization. The smaller the particles, the deeper these penetrate into the lungs and the greater the damage they cause to health as a result.

Many sources of particulate air pollution

About 50 per cent of all particulate matter is produced by so-called primary particles that enter directly into the atmosphere through automotive emissions or heating exhaust pipes. The other half is produced in the air from precursor substances such as nitrogen oxides, sulphur dioxide, ammonia, and hydrocarbons. On a typical winter’s day in Zurich, around a quarter of the tiniest and therefore particularly damaging PM1 particles are produced by traffic, with a further 20% accounted for by industry and wood-burning. Other lesser contributors include agriculture as well as oil and gasburning fires. In the villages of the Alpine valleys, the main cause of fine particulates in the air tends to be not car emissions, but wood burning.

Situation improved by particle filters

Around three million people in Switzerland are affected by too high a level of particulate matter in the air. The repercussions are evident: difficulty in breathing, asthma and chronic bronchitis, as well as an increase in circulatory disorders and manifestations of cancer. Every year, up to 4’000 people die prematurely from these secondary health problems. A particular source of damage comes in the form of soot particles from diesel engines and wood-burning heaters, as these are known to be carcinogenic. Factory-fitted particle filters on diesel engines, optimally designed wood-burning devices, and virtually particle-free wood gasification processes reduce direct fine particulate emissions significantly. Further reduction can be achieved by ensuring better thermal insulation for buildings. This reduces heating requirements and therefore also reduces the emission of fine particles and precursor substances.