A risk-based approach to health impact assessment for input-output analysis. Part II

Goal, Scope and Background

In the first part of this paper, we developed a methodology to incorporate exposure and risk concepts into life cycle impact assessment (LCIA). We argued that both risk assessment and LCIA are needed to consider the impacts of increasing insulation for single-family homes in the US from current practice to the levels recommended by the 2000 International Energy Conservation Codes. In this analysis, we apply our model to the insulation case study and evaluate the benefits and costs of increased insulation for new housing.

Results and Discussion

The central estimate of impacts from the complete insulation manufacturing supply chain is approximately 14 premature deaths, 400 asthma attacks, and 7000 restricted activity days nationwide for one year of increased fiberglass output. Of the health impacts associated with increased insulation manufacturing, 83% is attributable to the supply chain emissions from the mineral wool industry, which is mostly associated with the direct primary PM2.5 emissions from the industry (98%). Reduced energy consumption leads to 1.2 premature deaths, 33 asthma attacks, and 600 restricted activity days avoided per year, indicating a public health “payback period” on the order of 11 years. Over 90% of these benefits were associated with direct emissions from power plants and residential combustion sources. In total, the net present value of economic benefits over a 50-year period for a single-year cohort of new homes is $190 million with a 5% discount rate, with 49 fewer premature deaths in this period.

Conclusion

Recommendation and Outlook. We have developed and applied a risk-based model to quantify the public health costs and benefits of increased insulation in new single-family homes in the US, demonstrating positive net economic and public health benefits within the lifetimes of the homes. More broadly, we demonstrated that it is feasible to incorporate exposure and risk concepts into I-O LCA, relying on regression-based intake fractions followed by more refined dispersion modeling. The refinement step is recommended especially if primary PM2.5 is an important source of exposure and if stack heights are relatively low. Where secondary PM2.5 is more important, use of regression-based intake fractions would be sufficient for a reasonable risk approximation. Uncertainties in our risk-based model should be carefully considered; nevertheless, our study can help decision-makers evaluate the costs and benefits of demand-side management policy options from a combined public health and life cycle perspective.