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The Framework Directive 1999/30/EC (Annex VI, Art. II) prescribes a sampling height from 1.5 m to 4 m: “in general,
the inlet sampling point should be between 1,5 m (the breathing zone) and 4 m
above the ground. Higher positions (up to 8 m) may be necessary in some
circumstances.”
The measuring height is mostly 3.5 m in the measuring
network of Saxony, because of risk of lost
of data due to false measuring caused by Vandalism. This height is also used
with common measuring containers.
During a one year measuring campaign in a street canyon of Leipzig the
variability of air pollutant concentrations were monitored in a height of 1.5 m
and 3.5 m. There are 30,000 cars per day including 7% heavy duty traffic. The
street canyon was 19 m wide and 21 m high.
The relations between the concentrations of 1.5m to 3.5 m
(K) were calculated on the basis of daily averages. It was high for benzene
(K=1.61) and NO (K = 1.46), but can be neglected for NO2 (K = 1.04).
This means that in 1.5 m height the concentration of benzene is 60% higher than
in 3.5 m. This finding demonstrates that the load in the breathing zone is
significantly higher, than in 3.5 m height.
There has been also found significantly 20% higher
relations of concentrations in summertime compared to wintertime. There was
found no correlation between the relations of concentrations and wind speed,
wind direction, air temperature and air humidity.
Web page/Source in German:
Löschau, G. (2000):Immissionssmessungen an
Verkehrsschwerpunkten – Höhenabhängigkeit der Immission in einer
Straßenschlucht, in: SÄCHSISCHES
LANDESAMT FüR UMWELT UND GEOLOGIE: Jahresbericht zur Immissionssituation
1999. Materialien zur Luftreinhaltung
2000.
http://www.umwelt.sachsen.de/de/wu/umwelt/lfug/lfug-internet/veroeffentlichungen/verzeichnis/Luft-Laerm-Strahlen/Immissionsbericht2001.pdf
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