Rather than analysing city-specific problems, SIENA provides a
‘laboratory’ within which to analyse generic, methodological
questions relating to exposure assessments that are faced by the
majority of environmental health studies in urban settings.
The approach adopted in the development of SIENA is to sacrifice
precision for realism and generality (Levins, 1966) which allows
exploring general tendencies, such as the increase or decrease of
parameters or the deviation from a certain value