The air quality index (AQI) is used for the environmental toxicological evaluation of the air based on our measurement data. Its calculation is based on official specifications of the environmental authorities. The measured values of various pollutant indicators are incorporated into 1-hour, 8-hour and 24-hour averages. In order to meet our extended requirements, we have extended our AQI according to the recommendations of the WHO and the EU Air Quality Directive, as well as according to models of the EU Common Air Quality Index (CAQI) and the LQIs of some cities.

Particulate matter is mainly generated during combustion processes in engines and in heavy industry. But particulate matter also occurs naturally in our air. For example, it is produced in large quantities during volcanic eruptions and landslides. An increased amount is mainly found in urban areas. Health effects can manifest themselves in irritation of mucous membranes, respiratory and cardiovascular diseases and malfunctions of the autonomic nervous system.

Particulate matter includes all particles below a diameter of 10 µm. The causes are basically the same for all particle sizes. The suspended particles are released into our environment by traffic, industry and of course events such as volcanic eruptions. The particle size results in different effects on our health. In the range of 2.5 µm - 10 µm the particles are too large to penetrate deep into our organism. Nevertheless, they cause inflammation of the mucous membranes and trigger asthma and allergies.

Ground level ozone is formed by photochemical reactions of other pollutants when exposed to intensive solar radiation. High concentrations can have serious effects on human health. From irritated eyes and mucous membranes to respiratory diseases, there can be considerable physical impairments, which can severely affect asthmatics in particular.

Nitrogen dioxide is an undesirable by-product that is produced in combustion processes, for example in engines and furnaces. In cities, road traffic is the main source of nitrogen dioxide. This increased volume poses a health risk, especially for asthmatics, as it can lead to bronchial constriction and respiratory problems.

Carbon monoxide is caused by the incomplete combustion of fuels and combustibles. Road traffic, for example, is therefore one of the primary sources. Especially conurbations are affected, as there is an increased traffic density. Under the influence of carbon monoxide, the ability of humans and animals to absorb oxygen decreases, which in the long term damages the central nervous system.

Ammonia is mainly produced in the agricultural industry. Livestock farming is a major source. Cigarette smoke and cleaning agents also cause ammonia to be released by chemical processes. It contributes to the formation of secondary particulate matter and ground-level ozone and can damage human health in this way.

Sulphur dioxide is mainly produced during the combustion of fossil fuels such as coal and oil, and the associated oxidation of sulphur. The pollutant irritates the mucous membranes and causes respiratory problems for humans and animals. Furthermore, the acidification of soils and waters leads to negative effects on ecosystems.