How does traffic create fine dust?

They come from engines, but also from brakes, tires, and asphalt. Among the damages, according to a scientific study, is an increased risk of dementia.

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How does traffic create fine dust?

The deadly fine dust (PM10 and PM2,5, the first with a diameter of less than 10 micrometers, the second with a diameter of less than 2,5 micrometers) are nothing other than microscopic particles, suspended in the air, which can penetrate, with potentially serious consequences for health, into the lungs and, in the case of PM2,5, even into the blood.

 One of the main sources is the traffic of vehicles, through two main mechanisms: direct emissions and secondary formation.

Direct emissions

In the case of direct emissions, the microparticles are already ready at the time of emissions, and their characteristics vary depending on the engine. But also mechanical wear (of brakes and tires) and the asphalt consumption Due to traffic, they generate fine dust.
In particular:

  • Physical education Diesel: are the main culprits of PM10 and PM2.5.
  • Petrol engines: Diesel engines, especially older or filterless models, are the next leading source of direct emissions for PM10 and PM2.5.
  • Brakes: the material of the pads and discs (copper, iron, carbon, etc.) disperses into the air in the form of particles.
  • Tyres: friction with the asphalt produces rubber particles and additives.
  • Asphalt: the wear of the road itself releases solid particles.

Secondary education

Fine dust secondary they are not emitted directly, but are formed in the atmosphere starting from polluting gases that react with each other:

  • NOx (nitrogen oxides): are emitted by engines, especially diesel ones.
  • SO2 (sulfur dioxide): It is less common in modern vehicles, but is present in some fuels.
  • VOC (volatile organic compounds): they come from the exhaust fumes
  • NH3 (ammonia):  It comes from agricultural sources, but can combine with traffic emissions

These gases react with sunlight, moisture, and other substances, and turn into solid or liquid particles (such as sulfates, nitrates, and secondary organic matter).

Damage caused by fine dust particles caused by traffic

Among the main health risks of fine particles caused by traffic, there are not only chronic lung diseases, including cancer, and cardiovascular problems. A broad analysis conducted by researchers at the University of Cambridge examined data from 51 studies on more than 29 million people, finding that exposure to PM2,5, carried mainly by traffic, increases by 17% risk of dementia for every 10 µg/m³ increase. 

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Cover photo by Life Of Pix via Pexels

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