PM2.5 and PM10


PM 2.5 and PM 10 refers to small air born particles, i.e. Particulate Matter, where PM 2.5 has a diameter less than 2.5 µm (micrometers) and PM10 a diameter smaller than 10 µm. PM10 particles are small enough to penetrate and get deep into the lungs, while PM2.5 particles, with their even smaller size, are so small that they can also penetrate the lung barrier and enter the blood system. Because of this PM2.5 can trigger, or worsen, several diseases. The larger fractions of PM10 are large enough for more of the human body's defenses to be effective against them and are thus not considered as harmful as PM2.5.

The smaller the particles are, the longer they can stay in the air and the longer they can travel.

Common sources

Airborn particles small as PM 2.5 are mainly created during combustion. Common sources of PM2.5 include power plants, residential wood burning, combustion in motor vehicles. Other sources include forest fires, agricultural burning and dust storms.

Related issues

PM2.5 can be a triggering, or worsening, factor behind heart attacks and several chronic diseases as bronchitis, asthma and other respiratory problems. There is also plenty of scientific evidence that links exposure of fine particles with premature death from heart and lung disease.


Current situation

The largest source of PM2.5 in Sweden is residential wood burning followed by emissions from industrial process and emissions from traffic (link). Emissions from all these sources have declined over the past decade, but because the total amount of traffic has increased there has been an increase of emissions from brakes and of abrasion particles, produced from road surfaces by use of (especially studded) tires. According to the WHO ambient air pollution is responsible for the deaths of about 3 million people annually and is affecting all regions of the world. About 90% of the global population breathes air that doesn't comply with WHO's air quality guidelines.

PM2_5 Exposure trends