Environmental Engineering Reference
In-Depth Information
micro-environment than the 'standard' model output. An example of this kind of
3. Application in a Human Exposure Study
We ran a 4-years period simulation over Paris region in order to create a long data
base of spatially resolved concentration data for use in an exposure study (2001-
2004). Apart from the grid-averaged concentration we also modelled the
'residential' and 'traffic' sub-grid scale concentration components. Demographic
data on the population of Paris were selected and by means of a Monte-Carlo
model we created a simple data-base of human activity patterns. Human activity
patterns in this study refer to the time people spend at (a) home, (b) work, and (c)
transportation. We then expressed daily averaged human exposure as the weighted
sum of three terms: (a) exposure at the place of residence; (b) exposure at the
place of work; (c) exposure to traffic, with relative weights the time spent by the
individual at each micro-environment. Modelled, grid-averaged concentrations at
the grid-cells corresponding to the place of residence and work were used for the
evaluation of the first and second terms of the exposure formulation respectively.
For the third term of exposure formula we used the 'traffic' component of sub-grid
scale concentration.
Fig. 1.
Comparison between modelled and measured NO
2
concentrations at a background and a
traffic monitor stations
Even if the time people spend in transportation is very low compared to the
time spent in the other two micro-environments, the difference between ambient
concentration levels is very high. Consequently, even if the relative weight of the
traffic exposure term is low it may still play a significant role in the overall, daily
