Environmental zones and driving bans exist primarily to keep air pollution, i.e. the pollutants present in the air, as low as possible. But what exactly are these pollutants and why are they so dangerous?
The best-known air pollutants are probably particulate matter, nitrogen dioxide and ozone. The government has set limits for them. The concentration of pollutants must remain below these limits in order to protect citizens.
Particulate matter is suspended matter of different sizes. Therefore, depending on their diameter, a distinction is made between PM10 (particles up to 10 micrometres in diameter), PM2.5 (up to 2.5 micrometres) and PM0.1 (particles of less than 1 nanometre). A micrometre, by the way, is a millionth of a metre. Written out, it would have 5 zeros after the decimal point, as 0.000001 metre. So the particles are unimaginably small and invisible to the naked eye. Fine dust can be created from different materials. In nature, for example, it occurs in the form of sand and sea spray. Combustion processes such as those in cars produce soot, which can also be dissolved in the air as fine dust. Brake abrasion from cars also produces fine dust from metallic substances. Fine dust can cause irritation and inflammation in the respiratory tract and lungs.
Nitrogen dioxide is primarily emitted by diesel vehicles and, when pollution levels are high, repeatedly raises the issue of diesel driving bans. Nitrogen dioxide, which is composed of one nitrogen atom and two oxygen atoms, can directly cause irritation of the respiratory tract and mucous membranes when inhaled. Nitrogen monoxide, the compound of nitrogen with only one oxygen molecule, is a precursor molecule of ozone.
Ozone, the compound of three oxygen atoms, is also very dangerous to health and causes inflammation of the mucous membranes and breathing difficulties. It develops from precursor substances and under the influence of energy, such as solar radiation. Therefore, ozone is a problem especially on hot and sunny days.
All these pollutants have one thing in common: they penetrate deep into the lungs, where they damage human tissue. They are all extremely reactive and quickly form so-called free radicals. These in turn react with components of the human body, for example with enzymes, protein building blocks and nucleic acids such as our DNA. Since the small particles can also pass into the blood, air pollution can affect not only the lungs, but organs such as the heart and brain. A large number of cardiovascular diseases have been attributed to air pollution.
Recent research has also focused attention on microplastics dissolved in the air. Traffic is a major contributor to air-dissolved microplastics, mainly through the abrasion of tyres and brakes. If the term air pollutants is defined more broadly, noise can also be added. Noise generated by motorbikes and tuned vehicles is passed on through the air and damages human health. In Außerfern, Austria, an environmental zone has already been set up against loud speeders to protect residents from the noise.
By the way: just because a certain limit value is met does not mean that the air is "clean". Because "clean" is a matter of definition! Opinions differ on the amount of pollutants that are harmful to health. Although the air in many metropolises in Asia is sometimes about 10 times as dirty as ours, the World Health Organisation considers even our levels to be harmful to health.
You can find out more about the health consequences of air pollution on our website under the menu item "Environment & Health".