Ultra-fine particles make up only 10% of the mass, but 90% of air pollution. Nevertheless, they are not yet adequately taken into account in current legislation, which only addresses the mass of particles. Initially, via a limit value for PM10 (particles with a diameter of fewer than ten μm) and since 1.1.2010 additionally via a limit value for PM2.5 (particles with a diameter of fewer than 2.5 μm). Such particles can be measured in any authorized laboratory. Even particles of the size PM10 are not visible to the naked eye and are significantly smaller than a human hair (50 μm). The investigations of the Leibniz Institute for Tropospheric Research (TROPOS) (Fig. 2) show that the proportion of organic and elemental carbon (OC/EC) is particularly high in the ultrafine particle range.

Investigations in Switzerland (2012) have also shown that nanoparticles transport substances on their surface that can trigger toxic reactions in the cells. “Fine dust” is a collective term that covers a large number of elements of different particle sizes. A significant component here is soot from incomplete fossil combustion. There is a correlation between the size of the particles and the adverse effects on human health as well as on the climate.

In recent years, therefore, the smallest particles – so-called ultrafine particles – have increasingly come into the public eye. Ultrafine particles are particles, agglomerates, and aggregates with a size smaller than 0.1 μm (< 100 nm), which are created as an undesirable by-product of the incomplete combustion of organic materials such as wood and diesel1. Particles of the size PM10 are mostly filtered out of the air we breathe in the nasopharynx and are emitted as if they were being blown before they enter the organism. Particles of the size PM2.5 already penetrate deep into the lung ramifications and irritate here, which can lead to asthma and other lung diseases and cause lung cancer.

Ultrafine particles can reach the alveoli via the respiratory tract. From there, the particles are transported into the blood and then into other organs3. Because of the high proportion of carbon in the ultra-fine range and the toxic substances that adhere to the nanoparticles and cause toxic reactions in the body, this particle fraction poses a particularly excellent health risk. The WHO confirmed in June 2012 that diesel engine emissions (these are ultra-fine particles) are carcinogenic and the leading cause of premature death6 from environmental causes.

The same category of risk includes substances such as arsenic and asbestos, which have been banned in the EU for many years. This is also confirmed by an increasing number of research results on the effects of diesel exhaust and ultra-fine particles and increases the pressure on legislators to reduce emissions from all diesel and wood-based sources using further measures (bans on the use of vehicles and stoves or mandatory use of filter technology).