Air pollution from high levels of particulate matter (PM) is a major environmental and health problem in many European cities. Raised levels of these tiny, solid particles in the air are linked to health hazards such as heart disease, breathing problems and lung cancer.

The European Commission estimates that the problem causes 300 000 early deaths each year, with the major contributors to PM being motor vehicles - particularly diesel engines - domestic fuel burning, and industry.

Such pollution is a special problem in the cities of Klagenfurt, Graz and Bozen (Bolzano) in Europe’s southern Alpine region, which took part in this LIFE project. This is partly because of their geography and climate. In some areas, air pollution has been exceeding the EU limit of 50 µg/m³ for microdust - PM10 - on more than 100 days each winter. Some recorded concentrations have been greater than in densely populated areas such as London.

The situation is to some extent alleviated in the summer when warm air and winds lift the particles and distribute them over a wider area, but is at its worst for the six winter months, and re-suspension - the taking up of deposited dust particles from the roads back into the ambient air – is a particular factor.