Eco-indicator 99 impact assessment method for LCA

Human health

Damages to human health are expressed in Disability Adjusted Life Years or DALY’s. This method, developed by Murray, is used by WHO and WorldBank. An important element is a scale that rates the different disability levels. Damage models were developed for respiratory and carcinogenic effects, the effects of climate change, ozone layer depletion and ionizing radiation.

In these models four steps are used:

• Fate analysis, linking an emission (expressed as mass) to a temporary change in concentration.
• Exposure analysis, linking this temporary concentration change to a dose.
• Effect analysis, linking the dose to a number of health effects, such as occurrence and type of cancers.
• Damage analysis, links health effects to DALYs, using estimates of the number of Years Lived Disabled (YLD) and Years of Life Lost (YLL), (following [Hofstetter 1998]).

Ecosystems

Damage to ecosystem quality is expressed as the percentage of species disappeared in a certain area, due to the environmental load (Potentially Disappeared fraction or PDF). The PDF is then multiplied by the area size and the time period to obtain the damage.

• Ecotoxicity is expressed as the percentage of all species present in the environment living under toxic stress (Potentially Affected Fraction or PAF). As this is not an observable damage, a rather crude conversion factor is used to translate toxic stress into real observable damage, i.e. convert PAF into PDF.
• Acidification and Eutrophication are treated as one single impact category. Damage to target species (vascular plants) in natural areas is modelled. Unfortunately the model was only available for the Netherlands, and it is not suitable to model phosphates.
• Land use and land transformation is based on empirical data of occurrence of vascular plants as a function of land use types and area size. Both local damage on occupied or transformed area and regional damage on ecosystems are taken into account.

Resources

Damages to Resources, minerals and fossil fuels, are expressed as surplus energy for the future mining of resources [Müller Wenk 1998].

• For minerals geostatistical models are used that relate availability of a resource to its concentration.
• For fossil fuels surplus energy is based on the future use of oil shale and tar sands.

Weighting

To create a weighting set 365 questionnaires were sent out to a Swiss LCA interest group: 82 were returned; 45 of these could be used as the basis for the weighting factors [Mettier 1999]. The panel members were asked to rank and weigh the three damage categories as well as a number of questions regarding attitude and perspective on society. On the basis of this information some of the respondents could be distinguished as using a perspective that fits within one of the three archetypes used in this project.

• In the default Hierarchist perspective contribution of Human Health and Ecosystem Quality is 40% each. Respiratory effects and greenhouse effects dominate Human Health damages. Land use dominates Ecosystem Quality; Resources is dominated by fossil fuels.
• In the Egalitarian perspective, Ecosystem Health contributes 50% to the overall result. The relative contributions within the damage categories are about the same as in the Hierarchist perspective, except for carcinogenic substances. A Hierarchist would consider a substance as carcinogenic if sufficient scientific proof of a probable or possible carcinogenic effect is available (IARC class 3 and up).
• In the Individualist perspective, Human Health is by far the most important category. Carcinogenic substances however play virtually no role. The individualist would only include those substances for which the carcinogenic effect is fully proven (IARC class 1). The Individualists would also not accept (based on experience) that there is a danger fossil fuels can be depleted. This category is left out. For this reason Minerals become quite important.