Particulate matter consists of a mixture of solids and liquid droplets. Some particulate matter is emitted directly, otherwise it forms when pollutants emitted by various sources react in the atmosphere.

Particulate matter comes in different sizes, with that smaller than 10 micrometers able to enter our lungs and cause serious health problems.

  • PM10 is particulate matter smaller than 10 micrometers in diameter.
  • PM2.5 (or fine particles) is particulate matter smaller than 2,5 micrometers in diameter.

Both the EU and World Health Organization consider the total mass of PM10 and PM2.5 as the indicator for the definition of their standards.

Particulate matter has been linked with illnesses and deaths from heart or lung disease. The World Health Organization has collected enough scientific evidence to state that the most harmful exposure to particulate matter is long-term exposure to fine particles (PM2.5). Please also visit our section on health impacts of air pollution for further information.