High levels of air pollution have plagued many Swiss towns and cities over the past few days.This content was published on December 16, 2004 - 16:29
Experts warn that the high concentrations of fine particles in the air pose a serious health hazard.
During the winter months, the skies over Switzerland’s low-lying regions are regularly covered by a thick layer of fog whereas the mountain resorts bask in glorious sunshine.
The air quality in many towns and cities has worsened with the increase of the fine particles known as PM10.
Over the past few days, pollution has exceeded the permitted levels of 50 micrograms per cubic metre by 20 per cent.
Health experts blame the high concentrations for the rise in respiratory problems, including asthma, cardiovascular conditions and even lung cancer.
Weather to blame
The current situation is the result of what is known as inversion, when a layer of air near the earth is cooler than that above it.
This specific meteorological condition traps the fine particles between the layers until there is a change in the weather.
But the Federal Environment Agency says many people suffer from health problems even if pollution is within the permitted levels.
The agency estimates that three million people in Switzerland, more than 40 per cent of the population - live in regions which record above average PM10 levels.
The differences between rural and urban areas are relatively small. Experts say this is because fine particles are easily carried by the wind and due to a chemical reaction in the air.
Traffic and industry
Traffic, in particular diesel-powered vehicles, is the main polluter according to a study conducted in Austria, France and Switzerland in 1999.
They account for 50 per cent of fine particles, while industry is blamed for another 30 per cent.
The environment office has put forward a series of measures to reduce the effects of winter smog.
In a 2001 report, the agency recommended stricter controls of car emissions and heating systems. It also suggested speeding up the introduction of particle filters and catalytic converters for diesel-powered engines.
swissinfo, based on an article previously published by NZZ
Winter smog directly affects more than 40 per cent of the Swiss population.
The pollution is caused by high levels of PM 10 particles and inversion.
Permitted PM 10 levels in Switzerland: 50micrograms/m3.
Traffic, particularly diesel engines, are blamed for most of the pollution.