Particulate matter describes tiny pieces of solid or liquid matter in the atmosphere. The main sources in urban areas are diesel-engined road vehicles, industrial, public, commercial and residential combustion.
Particulate matters are categorised based on size:
- PM10: Particles with a diameter of 10 micrometers (µm) or less, which can enter the respiratory system and cause health issues.
- PM2.5: Fine particles with a diameter of 2.5 micrometers (µm) or less, which can penetrate deep into the lungs and bloodstream, posing significant health risks. The PM2.5 fraction is part of the PM10 fraction.