Pollutant Monitoring in Metropolitan Areas


Air pollution, especially in heavily populated cities, is a proven cause of many illnesses and premature deaths. The respiratory tract in particular is severely affected by this exposure.

Most governments and environmental agencies across the world have recognized the dangers of air pollution and implemented guidelines and limits on common pollutants such as carbon monoxide (CO), Ozone (O₃), nitrogen oxides (NOx), and particulate matter. Typically, real-time concentration values are nowadays made available to the public through displays in public places or online.

Small Particles with a Big Impact

Gases and the tiniest dust particles enter our lungs with every breath. The smaller these particles are, the deeper they can penetrate the lung tissue.


In addition to long-term damage to our health, short-term symptoms such as coughing, shortness of breath, or headaches occur. In areas with high pollution levels, such as busy roads, residents are permanently exposed to this situation. The long-term consequences are devastating not only for the health of the individual but for the whole of society.  In addition to high health care costs, the economy also suffers from work absences due to illness.

High Exhaust Gas Pollution in Cities

Especially in cities, individual motorized traffic is the main contributor to pollution. These pollutants are produced by incomplete combustion of hydrocarbon compounds in the fuel.


The best known of these is certainly particulate matter, which is caused primarily by diesel engines. These particles consist of carbon particles with a large surface area, to which other substances can attach. Depending on their size, they are divided into different classes (PM 10, PM 2.5, and PM 0.1; PM stands for Particulate Matter). In addition, they also contain many gases that are harmful to the environment and health. Carbon dioxide (CO₂) accounts for about 20% of total exhaust gases, which is known to have negative effects on the climate. Nitrogen oxides and carbon monoxide also account for a significant proportion. Both gases have a toxic effect on the respiratory organs and can cause irritation or inflammation even in the smallest quantities.

Sewage Treatment Plants Can Turn into Dangerous Workplaces

A significant share of air pollution comes from wastewater treatment. This process removes pollutants from water that originate from domestic, commercial and institutional sources.


During these processes, high concentrations of ammonia (NH3) can be generated, primarily from excreta. Ammonia is bound in urea and breaks down during wastewater treatment. At its most basic, this leads to unpleasant odors. At its worst, it can damage the health of staff. In low concentrations, this gas has an irritating effect on the respiratory tract and mucous membranes. At higher concentrations, it can cause burns in the respiratory organs and thus become life-threatening. If the ammonia enters the bloodstream, it is also a severe cytotoxin for the human organism. The protection of employees at exposed workplaces is therefore a priority. This can be easily achieved with reliable and low-maintenance measurement technology.

You Can Only Improve What You Can Measure

To avoid or reduce pollutants in the air, you first need to know how much of them are present. Therefore, measurement technology plays a significant role in reducing emissions.


All relevant air pollutants have absorption bands in the near and mid-infrared (IR) and can therefore be measured quantitatively using IR spectroscopy. The possibility of real-time measurement represents a major advantage of this measurement technique. For example, at times of increased traffic volume, regulatory interventions can be taken in a timely manner to protect the surrounding population. Since Axetris optical spectroscopy solutions require very little space, there are almost unlimited possibilities for integration.