ASCOPARG (the Association for the Monitoring and Preservation of Air in the Grenoble Region) is an organisation subsidised by La Métro which monitors the levels of polluting emissions in the Grenoble region and manages a fixed network of 16 monitoring stations, plus one mobile unit and a number of temporary units.

The monitoring sites are selected on the basis of criteria of population density, the presence of polluting industrial activity or highways, and topography, all significant points for monitoring air quality.

The law on air and rational energy use, which came into effect on 30th December 1996, requires local authorities to aim to respect the right of every citizen to breath air which is not damaging to health. It provides for measures to be applied in four areas: prevention, monitoring, reduction and elimination of pollution.

Air quality in the Grenoble urban agglomeration is monitored by ASCOPARG. The agglomeration's geographical position encourages the concentration of pollutants, and ASCOPARG has recorded worrying levels on occasions in the past.

Various emergency measures are implemented when there is a peak in ozone or nitrogen dioxide pollution. Different levels have been set, each of which is accompanied by its own emergency measure :

• 180µg/m3 for ozone; information limit: initiation of the procedure for reducing traffic speeds on the major city bypass motorways (70 km/h)
• 300 µg/m3 for one hour on two sensors or 350 µg/m3 on a single sensor, for ozone and nitrogen dioxide; warning level: implementation of alternate traffic measures with continuation of the revised speed limit.