FAQ
What type of pollution is caused by road traffic?
Air pollution exposure causes 40,000 deaths each year in France. How? Road transport comes top on the list of pollutant sources, neck and neck with the residential sector (home heating especially). Pollution is generated by vehicle traffic during chemical and physical reactions:
- Carbon monoxide (CO) is a poisonous gas that escapes when fossil fuel is burned at temperatures that are not quite high enough for full combustion. Oxygen and carbon molecules then join together to form carbon monoxide. When a vehicle starts its engine, it releases a lot of this pollutant into the atmosphere, but the amount varies depending on the vehicle and traffic conditions.
- Another source of pollution associated with traffic is nitrogen oxides (NOX): nitric oxide (NO) and nitrogen dioxide (NO2). Released during the fossil fuel combustion process, these two gases come into contact with water vapour and generate acids that interact with gases and volatile particles to form nitrates and other compounds that are harmful to respiratory health and the environment. They also contribute to acid rain.
- Fine particles (FP) include those in exhaust fumes that are generated by fuel combustion, and fine friction particles that are a result of tyre and brake wear and tear. Fine particles are complex composites. And unlike the fine particles in exhaust fumes, they do not change their composition on contact with other pollutants in the atmosphere. They are toxic due to their composition, shape and size: the finer the particle, the further it can penetrate inside the body. Unlike other sources of pollution associated with vehicle traffic (CO, NOX, HC, O3, FP from exhaust fumes), fine friction particles are here to stay, even as electric vehicles become more popular. Often underestimated by public policies and regulations, they are a major health risk, causing oxidative stress,* respiratory or cardiovascular disorders, cancers, neurodegenerative diseases (Parkinson, Alzheimer), etc.
- Unburned hydrocarbons (HC) are another source of pollution caused by traffic. They are generated when fuel combustion is incomplete. This mostly happens in poorly maintained engines and when vehicles are filled with low-quality fuels. Unburned hydrocarbons are released in exhaust gases. Made up of carbon (C) and hydrogen (H), the unburned hydrocarbons ejected into the air contribute to the formation of ozone. They are harmful to health and cause anxiety, cardiovascular disease, heart attacks, brain degeneration and an increased risk of cancer.
- Ozone (O3) is a so-called “secondary” pollutant which is not emitted directly by petrol or diesel vehicles but created during the chemical reaction between nitrogen oxides and volatile organic compounds under the effect of heat and sunlight. Its impacts on human health and the environment are serious: asthma, breathing difficulties and an increased risk of stroke.
* Oxidative stress occurs when a cell can no longer manage the excessive presence of toxic molecules, mainly from cellular respiration, free radicals. They can damage cells and DNA.
Discover more questions
There are 1.4 billion vehicles in circulation on the world’s roads. From the factory to the scrap yard, these vehicles require raw materials to be extracted from the earth, then emit CO2 and fine particles, which cause damage to our health and our planet. But what’s the solution? Use your car as little as possible, and opt for greener transport solutions: walking, cycling or public transport. But France is a very car-centric country. The best idea is to reduce – as best you can – how much pollution your car generates.
One in five deaths around the world is attributable to outdoor air pollution yet politicians are struggling to remedy the situation. In France, the government has even been found at fault by the Court of Justice of the European Union and the French Council of State for not doing enough, while air pollution causes more than 40,000 premature deaths every year. What’s to blame? Natural phenomena certainly contribute (pollen, forest fires, soil erosion, volcanic eruptions, etc.), but most of the damage is caused by human activity (agriculture, industry, transport, construction, etc.), which generates gases and fine particles. In some parts of France transport is the worst culprit, in others, agriculture comes top of the list. In the fight against outdoor air pollution in France, measures must now be taken on domestic heating and road transport, which are respectively responsible for half and a quarter of fine particle emissions in Ile-de-France.
Electric vehicles help fight against global warming and reduce the air pollution that causes 307,000 premature deaths in Europe every year. But electric vehicles are not a miracle solution. They require a lot of energy to produce, charging them may need large amounts of fossil fuels (depending on the source of the electricity used) and – like petrol or diesel cars – they emit fine friction particles.