There are always particles of different sizes in the air we breathe

There are always particles floating in the air. The number, size, shape and chemical composition of the particles varies greatly. Street dust can be detected especially during spring, but some of the street dust particles are so small that they cannot be discerned with the naked eye. Particles of all sizes may adversely affect your health.

The diameter of large particles is over 10 micrometres (µm). The largest of these can be seen with the naked eye. The large particles are mainly street dust or soil particles carried on the wind. They make the surrounding area dirty and less agreeable. In addition, large particle can cause irritating symptoms, such as a blocked nose, coughing and itching of the eyes and throat. Plant pollen is also large in particle size and can cause allergy symptoms.

The majority of street dust is thoracic particles with a diameter of less than 10 micrometres. They form as a result of road surface, ground grit, tyres and brakes breaking down as well as with wind and tyres from particles transported from construction sites, for example. There is a notable concentration of thoracic particles in spring. Spring is the time when the particles built up during the winter on the streets become airborne due to traffic and wind. Thoracic particles are carried into the lower airways in the trachea and bronchi.

The majority of street dust is fine particles with a diameter of less than 2.5 micrometres. Here, fine particles are mainly from exhaust gases, burning wood and long-range transport from outside our borders. Particles transported from elsewhere are also created in energy production, industry, controlled burning of fields and wildfires. Due to their small size, they stay airborne for a long time and are transported thousand of kilometres with air currents. Particles under 0.1 micrometres are classified as ultra small. In urban settlements, exhaust gases and small-scale wood combustion are the main sources of these. The fine particles are carried all the way into the pulmonary alveoli. Ultrafine particles can move from the alveoli into the bloodstream.