Page 243 - Materials Chemistry, Second Edition

10 Life Cycle Impact Assessment 229

10.10.4 Existing Characterisation Models

The complexity of the underlying reaction schemes and the high number of indi-
vidual contributing substances for which photochemical ozone formation charac-
terisation factors must be calculated calls for simplification in the characterisation
modelling. Existing characterisation models apply one of two approaches:
The first alternative is to simplify the non-linear and dynamic behaviour of the
photochemical oxidation schemes by modelling one or a few typical situations in
terms of meteorology, atmospheric chemistry and concomitant emissions of other
air pollutants. For each individual VOC, characterisation factors may then be
presented for each situation or in the form of a weighted average across the
situations.
The second alternative is to ignore the variation between individual VOCs and
concentrate on getting the spatial and temporal specificities well represented in the
characterisation model. This approach leads to spatially (and possibly temporally)
differentiated characterisation factors for VOCs (as a group, ignoring variation in
strength between individual substances), CO and NO x . Often methane is treated
separately from the rest of the VOCs (which are then termed non-methane VOCs or
nmVOCs) due to its very low characterisation factor which really distinguishes it
from the majority of the other VOCs.
The first approach is adopted in characterisation models based on the POCP
(Photochemical Ozone Creation Potential) or MIR (Maximum Incremental
Reactivity) concepts. The second approach is adopted in regionally differentiated
models which attempt to capture the non-linear nature of the ozone formation with
its spatially and temporally determined differences. For further details see Chap. 40
and Hauschild and Huijbregts (2015).

10.11 Ecotoxicity

The contents of this section have been modified from Rosenbaum, R.K.: Ecotoxicity,
appearing as Chapter 8 of Hauschild M. Z. and Huijbregts M. A. J. (eds.) LCA
Compendium—The Complete World of Life Cycle Assessment—Life Cycle Impact
Assessment, pp 139–162. Springer, Dordrecht (2015).

10.11.1 Problem

About 500 years ago Paracelsus stated that ‘All substances are poisons; there is
none which is not a poison. The right dose differentiates a poison and a remedy’.
Today’s toxicology science still agrees and adheres to this principle and in con-
sequence any substance emitted may lead to toxic impacts depending on a number
of driving factors: (1) emitted quantity (determined in the LCI), (2) mobility,