D. A. Tolle, D. J. Hesse, G. B. Chadwell, J. S. Cooper, and D. P. Evers
505 King Avenue
Columbus, OH 43201
Comparison of the three LCIA methods is based on the amount of effort for data collection and analysis, as well as correlation of the impact potential scores. The effort to collect site-specific environmental data and conduct air dispersion modeling on 9 chemicals for the simplified RA method, required about 24 times more effort than the PBT method and about 4 times more effort than the multimedia fate modeling method. As the number of regions/sites and chemical emissions decreases, the improved correlation of the multimedia fate modeling method is more likely to justify the increase in effort for use of this method instead of the PBT method. The multimedia fate modeling method may be more appropriate for LCIAs involving comparative assertions or governmental policy decisions, while the PBT method may be adequate for internal company decisions. Although the simplified RA method is assumed to be the most accurate of the three methods evaluated, the substantial effort for obtaining environmental characteristics information needed for dispersion modeling does not seem justified when there are more than two sites included in the LCIA.
Gregory A. Norris
Sylvatica/Harvard School of Public Health
147 Bauneg Hill Rd, Suite 200
North Berwick, ME 03906
Yurika Nishioka. Harvard School of Public Health
Susan Doll, Harvard School of Public Health
Olivier Jolliet, EPFL, Switzerland
The differing potential for unit emissions to lead to human health consequences as a function of whether they occur indoors or outdoors can be addressed using the concept of "Exposure efficiency." Exposure efficiency is the probability that a molecule of pollutant emitted from a source will reach and be inhaled by a human receptor. It can be estimated for different release environments by a variety of means.
This paper reviews the spectrum of methods that have been advanced by LCA practitioners for dealing with usage phase emissions to indoor air. In the context of a case study LCA comparison of flooring materials, the paper then addresses a number of issues which arise in LCAs of products with indoor air emissions. These issues include the wide variability in indoor air emissions within product classes; the need to convert testing data on emissions rates into total lifetime emissions data for use in LCA; and the availability of data on specific chemical species within important categories such as VOCs.
The paper proposes a new and integrated method for consistent treatment of indoor and outdoor emissions in LCA, and illustrates how use of this new method impacts results, conclusions, and data requirements for LCA.
Robert P. Anex
Science & Public Policy Program
University of Oklahoma
100 East Boyd St., Rm S-202
Norman, Oklahoma 73019
U.S. EPA (MS-466)
ORISE Research Fellow
Visiting Scientist at Harvard School of Public Health Phone:
26 W, Martin Luther King Dr.
Cincinnati, Ohio 45268
FAX: 513-569-71 11
A powerful graphical tool for dominance analysis was developed to make transparent model results from the damage approach to decision makers. Examples show how manipulative such tools can be without careful introduction. This includes the knowledge on what decision makers do observe, perceive, or expect as a consequence of environmental effects. Practically this means that the reference system may considerably vary with decision makers and that the interpretation tool has to allow for this variation. Within Life Cycle Assessment the focus is on impacts induced by the change in resource use and emission patterns due to improvements within or change to another product system. This implies marginal changes and therefore the valuation has to deal with the weighting of marginal damages. This adds to the inherent difficulty to perceive effects spread in time and place. A number of possible solutions are presented, empirical validation being the next step.
David W. Pennington
ORISE Research Fellow
Systems Analysis Branch, NRMRL
I) The merits and applicability of five categories of methodology are first illustrated with the help of a hierarchical framework and straightforward case study. The hierarchy is based on the level of representation of the environmental mechanisms (from fate, via exposure to toxicological potency) and perceived sophistication.
II) A comparison is then presented of two of the more prominent but structurally different methodologies (tiers 4 and 5 in the hierarchy) used in the US. The WMPT facilitates comparison in terms of key properties using a framework of expert judgment to reflect levels of concern in terms of Persistence, Bioaccumulation and Toxicity (PBT). Toxic Equivalency Potentials (TEPs) account for chemical fate, multi-pathway exposure and toxicity using a multimedia model structure. Using the same data for 318 organic chemicals and minimizing scenario differences, a strong relationship and parallel support role is demonstrated to exist between these two particular approaches in the context of human health.
III) Focusing data collection efforts can dramatically reduce the time required to compare a large number of chemicals or emissions using the more sophisticated multimedia approaches in the hierarchy. Based on model insights and a stated trade-off between data needs and error, four straightforward guidelines are presented to help predetermine which degradation rates (air, water, soil and sediment) are likely to be pertinent. The introduced error is generally less than an order of magnitude for the 318 chemicals when compared to the full human health, while the data requirements (1272 half-lives) and associated collection times are drastically cut.