Miljøtema, 25 – Roads to Healthier Traffic

Roads to Healthier Traffic

Traffic and air pollution

We are all affected by air pollution. In urban areas motor vehicles are major sources of air pollution. Also in the indoor air we are affected by contaminated air that invades houses.

Harmful substances

It is good to see that pollution of outdoor air has fallen markedly in recent years. For instance the content of lead in the air in Denmark has been significantly reduced. However, exhaust gases from cars still contain a number of harmful substances. The most important are:

Particulate matter (PM), including particles and dust. The particles are divided into different sizes, and the ultrafine particles are most harmful, because they may penetrate deeply into the lungs and release toxic substances directly into the blood. The particles aggravate respiratory diseases and affect persons suffering from cardio-vascular diseases.
Nitrogen dioxides (NO₂) irritate the mucous membranes in the respiratory tract and lungs. About 40 per cent of the total nitrogen dioxide pollution in Denmark originates from traffic.
Ozone is generated when nitrogen oxides react with volatile organic compounds, under the influence of solar radiation. Ozone is generated mostly in Central Europe, and carried to Denmark with the wind. Ozone irritates the mucous membranes and may cause pain in the eyes, the throat and the air passages, and cause difficulty in breathing during physical strain.
Carcinogenic polyaromatic hydro- carbons (PAH).

Petrol and diesel – pros and cons

Emissions of particles and nitrogen oxides (NO_x) from diesel vehicles are bigger than from petrol-powered cars. These substances are harmful to humans, and the impact of diesel vehicles on human health and the environment is therefore greater than that from petrol cars. However, they also release less CO₂, because they go much farther per litre of fuel than petrol-powered cars.

truck

Photo: BAM

In addition, traffic accounts for about 20 per cent of the total CO₂ emissions in Denmark, and this figure is increasing. Traffic, thus, contributes to the global greenhouse effect.

pollution is expensive The persons who suffer most from pollution are those who are most vulnerable: children, elderly persons, and persons suffering for instance from respiratory and cardio-vascular diseases. Under the effect of air pollution, ill and elderly persons in particular may die at a lower age.

Particles – the biggest culprit

Particulate matter – especially fine and ultrafine particles – is considered to be the substance in exhaust gases from diesel-powered cars that is most harmful to health, and the particles are most dangerous for people who suffer from cardio-vascular and respiratory diseases. From the new government report on particle pollution it appears that about 450 deaths could be avoided each year if all diesel-powered vehicles in Denmark were fitted with particle filters. In 2004 and 2005 the Finance Act reserves a total of euro 4 million for a scheme to support installation of particle filters.

traffic and industry

Photo: BAM