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Monitoring sites


Historically, air quality monitoring has been set up around a fixed network of permanent, continuous measurement installations, most of which are automatic. The advantage of these networks is that they provide real-time measurements 24 hours a day, and they enable warnings to be put out for the population, public authorities or industrial concerns.

Usual pollutants

Because of that wide variety of pollutants in the air, it is not possible to monitor them all on a routine basis; it is necessary to select specific pollutants that can be used as indicators for atmospheric pollution stemming from industrial, motor vehicle, photochemical or other sources.

 The following are among the most widely used indicators:

  • sulphur dioxide (SO2)
  • nitrogen oxides (NO and NO2)
  • ozone (O3)
  • particles in suspension (PM10 and PM2.5)


The measurement station locations are selected in compliance with national criteria to enable comparisons between data from one town to another.

Various typologies are thus defined.

  •  "Urban" stations
    These represent the air breathed in by most of the people living in an urban area.They are located in urban districts, away from the immediate, direct influence of a main road or an industrial installation.
  • "Traffic" stations
    These represent maximum exposure in areas featuring major levels of road traffic.
  • "Peri-urban" stations
    These represent maximum exposure to secondary pollution in densely populated areas under the direct influence of an urban district.
  • "Industrial" stations
    These represent maximum exposure in areas subjected to pollution of industrial origin.
  • "Rural" stations
    These represent pollution in sparsely populated areas, at a regional or national level.
  • "Observation" stations
    These do not meet the criteria for the above stations, but they help to enhance understanding of the pollution phenomena studied.