ParticulesNépal
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Népal
9. Particules
Les particules, ou matières particulaires (PM), sont de minuscules particules solides ou gouttelettes liquides en suspension dans l’air. Dans la circulation routière, les émissions de particules peuvent provenir des gaz d’échappement des véhicules, de l’usure des freins, de l’usure des pneus et de l’usure de la chaussée, ainsi que de la poussière remise en suspension par le passage des véhicules.
Les matières particulaires sont généralement classées selon la taille des particules. PM10 désigne les particules d’un diamètre allant jusqu’à environ 10 micromètres, tandis que PM2.5 désigne des particules plus fines allant jusqu’à environ 2,5 micromètres. Les normes d’émissions des véhicules, les filtres à particules et les mesures relatives à la qualité de l’air servent à réduire l’exposition à ces polluants.
What are particulates?
Particulates, or particulate matter, are very small solid particles or liquid droplets suspended in the air.
What are PM10 and PM2.5?
PM10 refers to particles with a diameter of up to approximately 10 micrometres. PM2.5 refers to finer particles with a diameter of up to approximately 2.5 micrometres.
Where do traffic particulates come from?
Road traffic can produce particles through engine exhaust, brake wear, tyre wear and road-surface wear. Passing traffic can also resuspend dust already present on the road.
Are diesel vehicles a source of particulates?
Yes. Combustion in diesel engines can produce very small soot particles. Modern diesel vehicles commonly use particulate filters to capture a large proportion of these exhaust particles.
What is a particulate filter?
A particulate filter is an exhaust-treatment device designed to trap particulate matter produced by an engine. Diesel particulate filters are commonly known as DPFs.
Do petrol engines produce particulates?
Yes. Petrol engines can also produce particulate emissions, particularly certain direct-injection engines. Appropriate emission-control systems may therefore include particulate filters.
Do electric vehicles produce particulates?
Fully electric vehicles produce no exhaust particulates from a combustion engine, but particles can still result from tyre wear, road wear and braking.
Are brake and tyre particles regulated?
Vehicle-emission regulation is increasingly addressing non-exhaust emissions. The European Euro 7 framework includes requirements concerning brake-particle emissions and tyre abrasion.
Is particulate matter the same as CO2?
No. Particulate matter consists of tiny airborne particles, while carbon dioxide is a gas. They are different types of vehicle emissions and are regulated for different environmental reasons.
How can vehicle particulate emissions be reduced?
Measures include effective particulate filters, cleaner vehicle technologies, correctly maintained emission-control systems and reductions in brake, tyre and road-wear emissions.
