Glossary
Soot and particulate matter are part of road traffic air pollution. Road traffic emissions are often higher in our urban areas, and in neighbourhood buildings, the air is slowly remixed.
Emissions from traffic also depend on the proportion of studded tyres, driving conditions and the proportion of vehicles that have just started when the engine and exhaust gas cleaning have not reached normal operating temperature. For these, emissions can be 100 times higher than from vehicles with fully heated engines and exhaust gas cleaning.
Particles are generated partly by incomplete combustion in the engines and partly as wear particles from tyres, roads and brakes. Particles smaller than 10 μm in diameter, PM10, can be inhaled by humans and can therefore be harmful to health.
The most vulnerable to the negative effects of air pollution are children, the elderly and people with asthma, lung or cardiovascular disease. For example, wear particles cause respiratory problems to a greater extent in people with asthma, while combustion-generated particles are more associated with cardiovascular diseases. Both wear particles and exhaust particles give rise to increased mortality, although it is likely that the coupling is stronger for exhaust particles.
Emissions can be reduced, for example with the help of purification technology such as particulate filters. Emissions of exhaust particles from road traffic have fallen sharply in recent years and by over 70 per cent since 1990.
