Air quality

The ISSeP manages air quality measurement networks. The latter are used to verify compliance with European regulations. They are also used to inform the population in case levels are exceeded (ozone spike, smog alerts). As the reference air laboratory, the ISSeP develops new analysis methods and audits and advises approved laboratories, and provides scientific support to competent administrations.


Modelling is used to map the data through the interpolation of timely measurements and also to predict future concentrations by simulating physical and chemical atmospheric processes.

Atmospheric emissions

The ISSeP also takes measurements at fixed sources (industrial chimneys) for both the administration and private parties. These measurements are used to verify compliance of operating licences within these industries.

Click here for ambient air quality data for the Walloon region.

Thematic correspondent for AIR quality: Benjamin Bergmans – 04 229 82 19


Operation of the air quality monitoring network in Wallonia

In order to evaluate the effectiveness of all measures taken in favour of the protection of the quality of air we breathe, and to verify the limits imposed by Directives 2004/107/EC and 2008/50/EC, it is important to have access to effective tools for analysing this air. For several years, Wallonia has used a monitoring network for characterising air quality. The ISSeP is responsible for operating these networks on behalf of the AWAC (Walloon agency for air and climate).
Click here   les données de la qualité de l’air ambiant en Région wallonne.

for ambient air quality data for the Walloon region.

A department is also responsible for controlling emissions from industrial chimneys and checking the compliance thereof with environmental permits. Given the high concentration of industries close to highly-urbanised sites, these measurements, in addition to the European reporting obligations (EMEP/CORINAIR) are also significant for establishing reduction plans.
The monitoring and scheduling of activities is managed by a technical committee composed of scientists working within the ISSeP, SPW managers, and external experts. A monitoring committee manages the coordination of the different environment quality monitoring networks.

The ambient air quality monitoring networks can be divided into three categories: the telemetric network, non-telemetric networks, and the mobile network.

  • The telemetric network
    It continuously measures various pollutants using automatic analysers situated in twenty-four stations distributed throughout Wallonia. The pollutants measured are as follows: sulphur dioxide, monoxide and nitrogen dioxide, carbon monoxide, ozone, gaseous mercury, “black carbon” and suspended particles (PM10 and PM2.5). This network also records meteorological parameters (wind speed and direction, temperature, pressure, relative humidity, and amount of precipitation).
  • Non-telemetric networks
    These networks study, based on samples collected in situ and analyses performed in the laboratory, various pollutants such as black smoke, volatile organic compounds and polycyclic aromatic hydrocarbons, sediment dusts, heavy metals in suspended particles, fluorides (particles and gaseous), mercury and wet depositions.
  • The mobile network
    This network is intended to measure the pollution in zones rarely studied, or zones presenting pollution requiring better characterisation, both in terms of pollutants emitted and their spatial distribution. It covers the sampling and analysis techniques for the telemetric and non-telemetric networks.

Emission measurement networks comprise 2 main activities: the control of waste from industrial facilities and the continuous control of dioxin emissions.

  • The industrial facility waste control network
    The aim of this network is to perform a comprehensive characterisation of the emissions of major pollutants from industrial facilities at the request of the administration. The pollutants assayed include mineral elements (heavy metals: Hg, Cd, Cr, etc., halogen compounds, etc.), organic elements (dioxins, PCB, VOC, etc.) as well as dust and gaseous pollutants (SO2, CO, NOx). The correlation with the self-control measurements imposed on manufacturers is also verified.
  • The continuous dioxin emission control network

Since January 2001, Wallonia has had access to a unique tool for the continuous control of dioxin emissions. In order to verify compliance with European directive 2000/76/EC concerning waste incineration, dioxin emissions from household waste incineration ovens are checked using continuous smoke sampling. The network is also extended to other types of facilities (cement plants, etc.) which may release significant amounts of this pollutant.

All measurements taken in the context of these networks are particularly important for checking air quality both in real time (alerts and public information) and in the long term (compliance with legal limits).

The institute is also involved in promoting environmental information. Its daily tasks consist of:

  • managing the air quality monitoring networks.
  • managing the formatting and the transmission of results;
  • checking the reliability of the sampling and analysis methods used;
  • developing new sampling and analysis methods for atmospheric pollutants;
  • participating in research and development programmes at the regional, state, and European level;
  • promoting knowledge of tools for monitoring air quality and atmospheric conditions;
  • providing technical and scientific assistance for administrations, companies, and individuals.

Air quality measurements at the request of other administrations, industries, or companies

The ISSeP has measurement equipment which can be used to assess air quality to solve occasional pollution problems, characterise sites with local specificities (nature of the pollution, topographical situation, etc.), provide, based on practical experience, data or opinions on pollution types and levels, validate models, or carry out a preliminary study before installing road or industrial infrastructure. At the industry level, the characterisation of emissions able to optimise the processes and recommendations on the standards and best practices are also provided.

Air quality can be evaluated using several types of complementary measurements:

  • continuous and real-time measurements using specific automatic analysers.
    The parameters subject to analysis are: sulphur dioxide, hydrogen sulphide, nitrogen oxides, ammoniac, methane and total hydrocarbons, ozone, carbon monoxide, monocyclic aromatic hydrocarbons, “black carbon”, particles in suspension (PM10, PM2.5 and PM0.1) and sedimentary dust. Some meteorological parameters may also be measured: wind speed and direction, temperature, humidity, and atmospheric pressure.
  • continuous samples for delayed laboratory analysis.
    Continuous samples can be taken using suitable devices. Samples are collected at regular intervals to subsequently be analysed by the laboratories that are part of the ISSeP’s air quality department. The parameters most commonly measured are: volatile organic compounds, polycyclic aromatic hydrocarbons, heavy metals, and sedimentary dust.

In terms of industrial chimney measurements:

  • the characterisation of the emissions from an industrial facility and the optimisation of production and treatment processes;
  • help for industries in choosing their reduction technique and calibrating their self-control system;
  • advice on best practices for constructing or extending a facility.

Expertise and advice

As a reference laboratory, the ISSeP offers its technical expertise to the administration and approved air laboratories. In addition to providing the administration with technical support, this function includes the development of analysis methods and their validation. The methods are then published in the form of a good practice guide and a list of approved laboratories is created. The institute also performs laboratory audits in the context of the approval procedure; see chapter “the reference laboratory” in this document.
As a sectoral operator, the ISSeP provides the NBN with technical assistance regarding standardisation of “air quality” and this at the level of CEN/TC264 and ISO/TC146. This include appointing experts, managing reflecting groups, monitoring the drafting and revision of relevant standards, providing documents, and managing votes for Belgium. In addition, several collaborators are experts and active in the different working groups.

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