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Geographic-ecological analysis is based on the
principle of the spatial linkage of health data and
risk factors. The current place of residence is
frequently taken as point of reference. The exposition
of a population to a risk factor, e.g. to air
pollutants, is assessed by means of the immission
level of the place of residence. In many cases, this
procedure proves to be more reliable than the
collection of individual exposition data (English,
1992; Morgenstern, 1998). It implies the differentiated
mapping of environmental risk factors in
terms of the area to be covered ± a task for which GIS
are highly suitable.
Data covering health-relevant environmental impacts
(water, soil, air) are often available only in the
form of pointwise measurements, from which the
spatial immission pattern has to be deduced. Many
GIS offer a number of interpolation techniques, i.e.
the trend surface analysis as a global respectively the
kriging as a local procedure (Briggs and Elliott,
1995), in order to deduce an area-wide immission
assessment from the point information.
Furth