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.

Pollutants generated by humans


Human activity generates primary and secondary pollutants. But how are these different? Primary pollutants come straight from sources of pollution such as industry, heating, transport and agriculture. They include nitrogen oxides (NOx), sulphur dioxide (SO2), volatile organic compounds (VOC), hydrocarbons and fine metal particles (lead, cadmium, etc.). Secondary pollutants are created in the atmosphere, as a result of chemical reactions between various pollutants that produce ozone, nitrogen dioxide and ultrafine particles.


Industries responsible for air pollution


How do we generate air pollution?


  • Leading the pack is the residential sector, especially home heating, and road transport. But it’s not the same up and down France. These activities are therefore respectively responsible for half and a quarter of fine particle emissions in Ile-de-France. Whereas in Haute-Savoie, in the Arve valley, 80% of polluting emissions come from individual wood heating systems. 
  • Industry also plays a major role in air quality. Factories contribute to pollution with sulphur dioxide (SO2), non-methane volatile organic compounds (VOCnM), PM10 fine particles and even nitrogen oxide (NOx) in France. Airparif estimates that more than 50% of sulphur dioxide pollution in Ile-de-France is generated by industrial activities. 
  • As for agriculture and forestry, they are not far off as the main sources of air pollution. Spreading, livestock effluents, etc. represent 93% of ammonia production (NH3), 42% of NMVOC emissions, 25% of PM10 emissions and 11% of PM2.5 emissions, according to the SECTEN 2021 report by Citepa. 
  • Non-road transport methods aren’t all squeaky clean either, especially planes. In addition to the CO2responsible for global warming, aeroplanes generate air pollution with fine particles, especially those related to nitrogen oxides (NOx), contrails, sulphur dioxide (SO2), and carbon particles.


A key public health problem


Air pollution is a major concern for both public health and the environment. We need to understand where it comes from and pinpoint the main sources of air pollution to arm ourselves better in the fight against this scourge that causes at least 40,000 deaths each year in France. But to finish on a positive note: In France, atmospheric pollution emissions are down since 1990 (heavy metals, acidifying and eutrophication pollutants, particles, and persistent organic pollutants).

Discover more questions

Stinging eyes, breathlessness, a cough that won’t budge: air pollution – especially when it’s cause by fine particles – is irritating, but can also be the cause of serious diseases. It even puts lives in danger: in France, air pollution cuts life expectancy by two years. And in New Delhi, this figure leaps to 10 years. In terms of deaths on a global scale, air pollution is just as dangerous as smoking, and even more serious than alcohol and unclean water (there are three times as many air pollution-related deaths) and HIV (six times more). Who is most at risk? People suffering from respiratory and cardiac disorders, diabetes, infants, seniors and pregnant women.
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.
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.