conclusions

Geographical, climatic, economical and social differences among the investigated towns and their peculiar conformations lead us to believe that the situations observed in the six MACBETH towns are representative of the average European situation. If the amount of gathered data and the strict validation processes they underwent are also considered, one can reasonably conclude that MACBETH results form a basis of knowledge of high scientific value, to be held in due consideration at the moment of issuing of the benzene Daughter Directive.

citizens' exposure level, whatever their
occupation or the fraction of the time spent
outdoor, is higher than urban average
level and is equal, on average in Europe,
to twice its value.

The surprising MACBETH results are consequence of the combined action of urban and indoor pollution. The former has a heavier relative influence in southern towns, the latter in northern ones, though experimental data leads us to think that home contamination derives anyway and anywhere from urban pollution.
Which is the reason for the heavier home than urban pollution? It is advisable that further research activities will be promoted to make the reasons clear, with the purpose of providing the lawmakers with instruments for intervening also in this field.

Finally MACBETH's innovative methodological approach stands as an applicative model nowadays adopted by small and large European towns, among which Paris, Rome and Brussels are worth mentioning.

this means that the risk level
for citizens is actually doubled
with respect to what one would
expect from the setting of any
limiting value to urban pollution