Road traffic is often pointed out to be an important local source for spreading metal to the environment. The content of many metals in the ground is usually high close to the road and decreases quickly as the distance from the road increases. Most likely the biggest particles are therefore deposited in the immediate vicinity of the road while smaller particles can more easily be spread in the atmosphere. The large-scale implications of road traffic to the environment cannot be identified through mark samples only and therefore there is also a demand for investigations of the aerosols.
The aim of this study is to:
- identify which types of metal that are issued from road traffic itself;
- quantify emissions with local and regional effects;
- discuss parameters with major effect on different emission factors.
The study has been carried out in two road tunnels in Gothenburg were the traffic structure, flow and speed were measured per tunnel tube. The traffic in both tunnels was measured at five occasions and for approximately two hours each time. The aim was to measure at the most diverse conditions possible.
The result show that the major occurrence of several metals in the air close to roads depends to a large extent on the amount of dust, and other material from the ground, that whirls up as traffic goes by. The whirl up of this material has also a big impact concerning the content of bigger particles in the tunnel air.
From a number of about twenty different metals the study shows that Ba, Cd, Cu, Pb, Sb and Zn is being spread by road traffic to an extent that the air gets dominated by these traffic emissions. These emission factors also represent the factors that through inhalation as well as deposition contribute to local and regional environmental influence.