A risk-based approach to health impact assessment for Input-Output Analysis. Part I

Goal, Scope and Background

Incorporation of exposure and risk concepts into life cycle impact assessment (LCIA) is often impaired by the number of sources and the complexity of site-specific impact assessment, especially when input-output (I-O) analysis is used to evaluate upstream processes. This makes it difficult to interpret LCIA outputs, especially in policy contexts. In this study, we develop an LCIA tool which takes into account the geographical variability in both emissions and exposure and which can be applied to all economic sectors in I-O analysis, relying on screening-level risk calculations and methods to estimate population exposure per unit emissions from specific geographic locations.

Methods

We develop our analytical approach with reference to the case of increasing insulation for new single-family homes in the US. We quantify the public health costs from increasing insulation manufacturing and compare them with the benefits from energy savings, focusing on mortality and morbidity associated with exposure to primary and secondary fine particles (PM2.5) as well as cancer risk associated with exposure to toxic air pollutants. We use OpenLC to estimate the incremental economic outputs induced by increased insulation and reduced fuel consumption and calculate emissions from a sector-specific pollution intensity matrix. We calculate sector-specific intake fractions (dimensionless ratios between the amount of pollutant intake and the amount of a pollutant emitted) using previously-derived regression models and apply these values to the supply chain emissions of fiberglass and fuel sources. We refine the exposure estimates for selected emission sites and pollutants that contribute significantly to total health impacts, running site-specific air dispersion models. We estimate health impacts using concentration-response functions from the published literature and compare the costs and benefits of the program by assigning monetary values to the health risks. In the second part of this paper, we present the results of our case study and consider the implications for incorporating exposure and risk concepts into I-O LCA.