Geoscience Reference
In-Depth Information
information. The statutory device that is used to prevent such pollution is controlled
by the different departments authorities in France. In this type of system air quality
management focuses on the pollution paroxysmique episode. The geographical
information that is produced as a result of this is, therefore, very specific and geared
towards the risk of an exceptional event The alert generates more attention than
general information trivialized through the use of the Atmo index. The aim of the
Atmo index is to quantify air quality in a geographicalal area using a dimensionless
figure generated from data recorded for different types of pollution. These different
pollution types are made up of different pollutants recorded at different measuring
sites.
THRESHOLDS (μg/m
3
)
POLLUTANTS
INFORMATION-
RECOMMENDATION
ALERT
400 or 200, if the procedure of
information-recommendation
was started the day before and
on the same day; and if forecasts
lead experts to think that an alert
may need to be raised the next
day
Nitrogen dioxide
200
500, if this value has been
exceeded for a period of 3
consecutive hours
Sulfur dioxide
300
1
st
threshold is 240 if this value
has been exceeded for a period
of 3 consecutive hours
2
nd
threshold is 300 if this value
has been exceeded for more than
3 consecutive hours
3
rd
threshold is 360
Ozone
180
Table 6.1.
Information-recommendation thresholds and measures taken
to alert the population (decrees from 02/15/2002 and 11/12/2003,
and the lawpassed on 08/17/1998)
The Atmo index, inspired by the American threshold index, is a ratio measured
between pollution levels and reference values that are calculated for each pollutant.
However, the use of this index is rather limited because it can only be used in areas
in which the exact same type of pollution is present. It is not possible to integrate
data produced by stations located near the source of pollution into this type of index
as this index does not take the quality of the surrounding air into consideration. In
