Particulate matter or fine dust is a mixture of solid and liquid particles with diameters smaller than 0.1 µm. This particulate matter (PM) is released into the environment through various processes and, due to its low mass, does not immediately sink to the ground. These types of dust or matter are therefore in the air for some time and, due to their small size, can get into the airways.
Fine dust is divided into PM classes (Particulate Matter) on the basis of particle diameters:
- PM 10: Particles that do not exceed a size of 10 µm and
- PM 2.5 Particles that do not exceed a size of 2.5 µm.
In general, the smaller the diameter, the deeper the fine dust can penetrate the airways.
The term fine dust encompasses primary and secondary fine dust. Primarily formed fine dusts arise directly at the source, such as in combustion processes or soil erosion. Secondary fine dust is only formed in a secondary formation process after the emission of gaseous substances such as sulphur and nitrogen oxides and ammonia in the air. Emission sources of secondary particulate matter pollution include precursor substances from animal husbandry and exhaust gases from vehicle traffic. These gases are transported through the air and can thus lead to secondary particulate matter pollution, far from their source of emissions.
Transport and industry are the main sources of fine dust emissions. While the energy industry used to contribute to fine dust pollution, the pollution values here have declined thanks to technological advances. Industrial countries facing an energy transition are therefore the most affected by fine dust pollution.
Nevertheless, despite advanced energy technologies, in metropolitan areas with increased road traffic, a particularly high concentration of fine dust in the air can be expected. Mainly caused by exhaust fumes from road traffic and the stirring up of dust when driving on the streets.
The weather can significantly contribute to exposure to fine dust; in periods of prolonged drought, the particles remain in the air for a long time and thus lead to increased concentrations.
Health risks from fine dust
The damage to health can vary greatly depending on the depth of penetration and the size of the particles. They range from inflammation of the bronchi and damage to the lung alveoli up to heart rate disorders. The following generally applies: the finer the dust, the further it can penetrate the organism through the respiratory tract. Coarse particles get stuck in the upper respiratory tract, while smaller particles penetrate into the lung tissue and ultrafine particles with a diameter of less than 0.1 µm into the bloodstream. From a health point of view, the small particles are therefore particularly dangerous.
The carcinogenic substances adhering to the particles pose a high risk potential. These can get into the airways through inhalation and thus, depending on their size, also into the tissue and the bloodstream, where they can have a carcinogenic effect. But even pure particle pollution leads to internal inflammation, severe respiratory diseases and cardiovascular disorders.
When it comes to fine dust there are no limit values below which pollution cannot be considered harmful - fine dust is always harmful.
Epidemiological studies show that even with low levels of particulate matter, there is an increased number of hospital patients with respiratory diseases and that the lifespan is noticeably reduced in regions that are more exposed.
The WHO estimates that 80% of air pollution-related deaths are due to heart defects, 14% to chronic lung diseases and 6% to lung cancer.
Fine dust in the air cannot be broken down, so it is important to reduce emissions as much as possible. This can either be done by foregoing the processes that cause emissions, or through technological progress that reduces emissions while maintaining the same level of performance.
Various emission targets have already been set by the WHO and the EU, and the countries are urged to take appropriate measures. Various strategies are introduced to try to reduce emissions. Since there is no limit, especially with fine dust, from which a harmless load can be assumed, fine dust emissions should be reduced to a minimum.
In general, the population is encouraged to develop a greater awareness of the development of fine dust, as the long-term damage can barely be estimated.
There are currently no official recommendations for personal protection against fine dust for the population. It therefore makes sense to orientate yourself on the recommendations and regulations of the public insurance companies and working groups for personal protection against fine dust at the workplace, including the information from the DGUV or BAUA. Respiratory masks should therefore be worn for personal protection against fine dust, and usually in industry to protect against fine dust and particles, or in hospitals to protect against viruses and other airborne pathogens. In general, FFP2-type breathing masks are recommended for most industrial sectors .
In the case of particularly high levels of fine dust, it is advisable to use dolomite-tested respiratory protection masks (BGR GUV R 190).
FFP2 masks are also recommended for workplaces with heavy exposure to diesel engine emissions according to TRGS 554 and for protection against nanoparticles that correspond to a size of 0.02 - 0.1 µm according to BGI / GUV-I 514 based on the results of Nanosafe 2 project.
Consumers should ensure that the particle-filtering half masks are correctly certified in accordance with EN 149: 2009; only then can the protective function against airborne particulate matter be ensured. A test substance with a particle size distribution of 0.02 µm to 2 µm (equivalent aerodynamic diameter) is used in the tests for filter permeability, breathing resistance and leakage. This includes the particle sizes of the PM classes for fine dust.
Sources and further information
German Federal Environment Agency:
World Health Organisation (WHO):
German Statutory Accident Insurance (DGUV):
Federal Institute for Occupational Safety and Health (BAUA):
EU – funded framework programmes: NanoSafe
 Amongst other things: FFP2 for wood dust according to BGI 738, for most activities according to BGI / GUV-I 8625 for hazardous substances in workshops and according to TRGS 559 occupational safety against mineral dust.