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3.3 IMPACT CATEGORIES
An impact category is defined as a class representing environmental issues of concern
into which life-cycle inventory results may be assigned. As has been previously
mentioned, Udo de Haes et al. (1999) have proposed classifying impacts in input-
and output-related categories. Input refers to environmental impacts associated with
material or energy inputs to the system and output corresponds to damages due to
emissions or pollutants, vibrations, or radiation. Table 3.1 gives an overview of input
and output impacts currently used in LCIA with a proposal of possible indicators.
Some of the impact categories mentioned in Table 3.1, such as climate change
and stratospheric ozone depletion, have a global effect; others, such as photo-oxidant
formation or acidification, have a local effect. This highlights the need for spatial
differentiation in the fate and exposure analysis in different impact categories. Figure
3.3 shows the global–local impacts for the different impact categories, each of which
is described next.

3.3.1 EXTRACTION OF BIOTIC AND ABIOTIC RESOURCES
This impact category includes the extraction of different types of nonliving material
from the natural environment. It is possible to distinguish three different subcate-
gories: extraction of (1) deposits (e.g., fossil fuels and mineral ores), (2) funds (e.g.,
groundwater, sand and clay), and (3) flow resources (e.g., solar energy, wind and
surface water). Examples of used indicator categories are: rareness of resources,
energy content of resources, mineral concentrations, degree of use of flow resources
in relationship to the size of the flow, total material requirement, and indicators

TABLE 3.1
Impact Categories and Possible Indicators
Impact categories Possible indicator

Input-related categories
Extraction of abiotic resources Resource depletion rate
Extraction of biotic resources Replenishment rate

Output-related categories
Climate change kg CO 2 as equivalence unit for GWP
Stratospheric ozone depletion kg CFC-11 as equivalence unit for ODP
Human toxicity HTP
Eco-toxicity Aquatic eco-toxicity potential (AETP)
Photo-oxidant formation kg ethene as equivalence unit for photochemical ozone
creation potential (POCP)
+
Acidification Release of H as equivalence unit for AP
Nutrification Stoichiometric sum of macronutrients as equivalence
unit for the nutrification potential (NP)
Source: Udo de Haes, H.A. et al., Int. J. LCA, 4, 66–74, 167–174, 1999. With permission.

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