FAQ

What are fine particles?

The term “fine particle” refers to an aggregate of polluting chemical compounds created during combustion, friction or chemical reactions. Forest fires, volcanic eruptions, and desert dust: fine particles can occur naturally. But most fine particles are generated by human activity. How? Mainly from road traffic (exhaust gases and abrasion caused by brakes on tyres and the road), home heating, and industrial and agricultural emissions.

Variable compositions

What makes up a fine particle? There is no specific formula. Soot, sulphur particles (SOx), nitrogen oxides (NOx), hydrocarbons (HC), and heavy metals such as copper, iron, barium, and zinc can all form fine particles. Their content, shape and size differs depending on what type of pollution has generated them.

PM1, PM2.5 and PM10

What is the difference between PM1, PM2.5 and PM10 fine particles? Fine particles are ranked by size. Ultrafine particles are called PM1 and have a diameter of less than 1 micron. The diameters of PM2.5 and PM10 are less then 2.5 and 10 microns respectively. To give an idea of scale, PM2.5 is the size of a red blood cell while PM10 is the size of a bacterium. The smaller a fine particle, the more dangerous it is, because it can penetrate deep inside the body. Its shape is also to be considered: the rounder it is, the more easily it forms clusters with other pollutants. And that creates a very toxic mix.

A sly threat

The answer to the question “What is a fine particle?” could also be that it is a dangerous pollutant that is everywhere, and invisible to the naked eye. Whether liquid or solid, fine particles create air pollution in heavily populated areas. When carried on the wind, they can also travel long distances and remain suspended in the atmosphere. As a result, according to the World Health Organization (WHO), nine out of ten citizens are exposed to air laden with fine particles. The larger particles that are not airborne are drained in runoff water and end up in rivers and oceans.

A threat to health

What impact do fine particles have? They pose a major issue for public health. Because breathing in particles means exposing your body to oxidative stress* and a host of respiratory (asthma, bronchitis), cardiovascular (arrhythmia, heart attack, thrombosis) and neurodegenerative (Alzheimer’s and Parkinson’s) diseases. They exacerbate existing illnesses, weaken vulnerable populations (children, the elderly, pregnant women) and put lives at risk. 17% of deathsfollowing lung cancer can be attributed to air pollution and fine particles. The WHO believes that this pollution is responsible for 4.2 million premature deaths per year globally. This impact is the same as that of tobacco consumption, but causes three times as many deaths as those that happen as a result of consuming alcohol and unsanitary water. Shocking.

* Oxidative stress occurs when a cell can no longer manage the excessive presence of toxic molecules, mainly from cellular respiration and free radicals. They can damage cells and DNA.

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What is the main cause of air pollution?

As we inhale 15,000 litres of air every day, we are continually exposed to air pollution, especially in large cities. These gases and fine particles are not only harmful to our health, but they also damage the environment and ecosystems and accelerate climate change. Where does air pollution come from? Although pollutants may be of natural origin: pollens, forest fires, sand mists, soil erosion, and volcanic eruptions generate pollution over which we have very little control, human activity is the main source of air pollution. That is evidenced by the sharp decline in air quality from the 19th century, with the development of industry and road traffic.

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:

What can we do to fight against air pollution?

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.