Page 303 - Materials Chemistry, Second Edition

4.5 Impact Categories, Impact Indicators and Characterisation Factors 287

critical air volume related to the nuisance by smells is obtained:

( m ) ( )
Smell potential = ∑ i m fU −1 (4.31)
3
OTV
i i
with m = mass of the substance i released into the air, for which an OTV was
i i
determined, per fU.
Here also a conversion into kg equivalent to a reference substance could be
obtained that would also make sense (same mechanism of smell perception).
Smells are extremely specific sensory perceptions, which can react to the smallest
chemical structural differences. It is therefore a problem, if an inventory only lists
cumulative values without reference to defined substances. Which is an odour
smell threshold value of ‘VOC’and/or ‘HC’, and so on? The same is also valid for
toxicities.
The smell should be quantified only with product systems where smelling
nuisances particularly for a comparison of products are concerned. A listing of all
smells by life cycle is not very informative.

4.5.4.3 Noise
Noise by the judgement of a majority of the population, subjectively belongs to the
most disturbing of environmental factors. It is to a large extent traffic-dependent,
but stationary plants and services can also be sources of noise.
In contrast to most other emission categories, where emissions are chemical
substances, noise as a release is a physical emission and from the receiver side
(like all sensory impressions) a physiological–psychological effect. Sound pressure
is quantified by a relative (logarithmic) scale (decibels). This unit is unfortunately
not suited to represent the total amount as a sum of partial amounts. In a direct
comparison of products (e.g. car, mowing machine) a standard distance can be
specified to measure the noise level of the device.
It is more difficult to include diffuse noises of multiple sources as for instance
traffic noise. For transport by truck as a first approximation the transport distance
per fU (vehicle-kilometres) can be used as a proxy instead. 348)
In model calculations for the highway from Milano to Bologna an equivalence
factor for cars and trucks was deduced. 349) A ‘disturbed time period’ of residents
is calculated and the limits of noisy loads that can be assigned to a nuisance
are adapted from regulations. Performances of transport are determined in the
inventory as passenger kilometres (car, rail, … ) and tonne-kilometres (truck,
rail, vessel, … ) (see Section 3.2.5). For the special case studied by Lafleche and
Sacchetto (1997) the following factors were calculated for the first time:

• number of disturbed human hours/passenger kilometre (car) = 0.000688
• number of disturbed human hours/tonne-kilometre (truck) = 0.000747.

348) Schmitz, Oels, and Tiedemann (1995).
349) Lafleche and Sacchetto (1997).