Atmospheric immissions and their impact on air quality

An atmospheric immission is the concentration of a pollutant detected in the atmosphere whose presence modifies the natural composition of the air. Its origin is linked to substances generated by anthropogenic activities that, in the form of gas, smoke, dust or other particulate matter, can alter the optimal conditions of the atmosphere.

The importance of atmospheric immissions is that they affect living beings and natural resources, since they also damage soil and water by modifying the composition of terrestrial and aquatic ecosystems. Their limits are regulated by standards and strict regulations that indicate their maximum concentration.

While atmospheric emissions come from a specific source of release, such as certain industrial processes in a factory or an aircraft engine, immissions are substances present in the atmosphere. These substances are concentrated at a specific location and are measured by air quality monitoring stations at ground level.

Tropospheric ozone is an example of an atmospheric immission that originates when the products of combustion engines react in the atmosphere with other substances. This process is activated by sunlight, which acts as a catalyst, generating a chemical reaction that results in the formation of ozone. Its presence causes the alteration of the proportion of this gas at ground level, better known as tropospheric ozone.

What is an atmospheric immission?

Immissions are pollutants that, after being emitted, are modified when they come into contact with the atmosphere. In this way, they can undergo changes by chemical and physical reactions when mixed with other substances in the atmosphere, and can be spread by being transported through the air.

These pollutant concentrations, or atmospheric immissions, are the amount of pollutants in a given unit volume of air. They are thus differentiated from atmospheric emissions, which are the pollutants emitted into the atmosphere from a given source.

Scientific studies are carried out to determine the limit value of the quantity of each atmospheric immission present in the air. In this way, the maximum permissible level of a pollutant is determined so that it does not have a toxic effect or its possible effects on human health and the changes it causes in the environment as a whole are reduced.

Differences between emissions and immissions

The relationship between immissions and atmospheric emissions is not straightforward. Once a pollutant is emitted, it can become an immission through chemical and physical reactions and the influence of the state of the atmosphere. It also undergoes transport and dispersion processes that can change over time.

The main differences between the two concepts are as follows:

Emissions

  • Their origin is the quantity of a pollutant that reaches the atmosphere from a given point or source.
  • They may be continuous or intermittent.
  • Although they can usually be localised to a specific point, they can also have a diffuse origin.
  • They are present in different states such as solid, liquid, aerosol, etc.
  • They are produced both by anthropogenic activities and by natural causes.
  • They are measured in units of weight over time, e.g. g/h, kg/year.
  • They can be drastically reduced if the emission source is eliminated.

Immissions

  • It is the concentration or level of a pollutant in a given area at a specific time.
  • The legal limits are based on scientific studies.
  • The importance of complying with regional regulations not to exceed atmospheric immissions beyond the established levels has a direct impact on human health and environmental protection.
  • These are expressed in units of weight of substance per unit volume, for example µ/m3 and g/m3.
  • The concentration of pollutants or atmospheric immissions is what is measured by sensor networks to determine the air quality in a given area in real time.
  • There is no direct correlation between the decrease or increase in concentration and the variation in atmospheric emissions.
Immission and Emission - Graphical illustration of atmospheric emissions and immissions - Kunak

Graphical illustration of atmospheric emissions and immissions

How to measure atmospheric immissions?

One of the key challenges for human health and well-being is to identify all substances that can affect air quality. In this context, environmental legislation and regulations play a key role in determining which immissions are acceptable and which must be controlled or eliminated to protect the common welfare.

The regulation of atmospheric immissions involves a detailed assessment of pollution levels and their impact on the environment. The authorities usually establish specific limits for different types of emissions, considering factors such as population density, industrial activity and the geographical characteristics of the area.

To implement control measures requires technology which, although not necessarily expensive, requires systems such as air quality sensor networks that provide accurate and reliable data (based on official reference data). It is essential that these measurements are carried out systematically and continuously to ensure the accuracy of the results.

Adequate analysis of the collected data provides information on the concentration of an air immission in a given area, as well as the point at which the permissible values are exceeded. It is necessary to analyse the data in the context of local and national regulations governing immissions. These regulations set specific limits for each type of immission, determining which levels are considered acceptable and which are illegitimate immissions.

When these permitted measures are exceeded, if there is no response from the local or regional government, the affected people and communities can resort to environmental justice. This is the legal instrument to ensure that such immissions are mitigated or, in extreme situations, measures are taken to identify the source of emissions where the contribution to the air of any of the pollutants is produced. It is therefore essential to adopt safety and precautionary measures to avoid that finally the atmospheric immissions are originated.

Ultimately, the proper management of atmospheric immissions not only benefits the individuals directly affected, but also contributes to the general welfare of the community and to the care of the environment.