The impact assessment on LCA consists of three parts: classification, characterization and total evaluation. At the phase of classification, the resource consumption or emissions are classified to the impact categories based on the potential environmental impacts.

Table 6.1.1 shows the default environmental impact categories list of the Society of

A. Input related categories (“resource depletion or competition”)

1. abiotic resources (deposits, fund, flows) glob

2. biotic resources (funds) glob

3. land loc

B. Output related categories (pollution)

4. global warming

5. depletion of stratospheric ozone

6. human toxicological impacts

7. ecotoxicological impacts

8. photo-oxidant formation

9. acidification

10. eutrophication (incl. BOD and heat)

11. odour

12. noise

13. radiation

14. casualties

Pro Memoria: Flows not followed up system boundary

input related (energy, material, plantation, wood, etc.) output related (solid waste, etc.)

Environmental Toxicology and Chemistry (SETAC)-Europe that is the academic society leading LCA studies. It is necessary to be clear which environmental categories are studied, depending on the “Goal and Scope definition”. At the phase of characterization, each assigned LCI data for an impact category is multiplied by a “Characterization Factor” (quantifiable representation of an impact category) and the output is shown as a numerical indicator, “Category Indicator”.

Fig. 6.1.3 shows a general procedure of impact assessment, taking global warming and ozone layer depletion as an example. The numerical value expressing potential environmental impacts of emissions, like "Global Warming Potential (GWP)", is often used for the Characterization Factor. It is to be noted that ISO-14040 defines that “classification and characterization” are mandatory elements but “normalization, grouping and weighting” are optional elements. Although it is possible for a practitioner to make indexes based on carbon dioxide or chlorofluoro-carbon in such impact categories as "global warming" and "ozone layer depletion", but they decided that to integrate these different environmental impacts and to make a single index for decision making is not possible.