Monitored pollutants

Among the many pollutant substances, Atmo Auvergne mainly measures pollutants targeted by French or European regulations or draft regulations setting concentration thresholds. These substances are generally indicators of the various types of pollution they represent (sulphur dioxides from industry; nitrogen oxides from cars; ozone from photochemicals reactions) or pollutants that have a sufficiently adverse effect to warrant the establishment of standards.

Gases
The main gaseous pollutants measured are:

	Nitrogen oxidese (NOx)		Carbon monoxide (CO)
	Sulphur dioxide(SO2)		Certain volatile organic compounds (COV)
	Ozone (O3)

Particulate matter
There are several indicators of particulate matter air pollution, linked to the size of the particles and measurement methods:

	Black smoke
	Particles in suspension (PM10)
	Fine particles (PM2.5)

Chemical analysis provides data on the atmospheric concentrations of various compounds aggregated on these particles, including:

Toxic heavy metals

Pollens
Atmo Auvergne and the National Network for Aerobiological Monitoring (RNSA) conduct joint analysis of pollen concentrations in air in the French departments Puy-de Dôme and Cantal. Atmo Auvergne collects and counts pollens in Clermont-Ferrand and Aurillac.

Radioactivity
Radioactivity is the spontaneous conversion of certain elements into other elements through nuclear decay. This process can be accompanied by a significant release of heat.
There are three types of radioactivity depending on the type of particle involved:

• Alpha ( a ) when a helium nucleus is emitted
• Beta ( b ) when an electron is emitted
• Gamma ( g ), when high-energy photons are emitted

The main unstable atomic nuclei that may undergo such conversion are:

• Radon, a natural radioactive element representing the main source of radioactivity to which populations are exposed
• Iodine, a highly radioactive element, and a much feared fission product if released into the atmosphere following a nuclear accident