Tuesday, November 2, 2010

Hazardous air pollutants- Highlights from EPA Workshop

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Estimating the Benefits of Reducing Hazardous Air Pollutants: Summary of 2009 Workshop and Future Considerations

(26 page pdf, Environ Health Perspect., Oct. 4, 2010)

Key Quotes:

“Challenges related specifically to benefits analysis for air toxics include uncertainties in emissions information, air quality and exposure modeling, effects estimation, and economic valuation, as well as distribution considerations”


  • “Emissions. EPA maintains an inventory of emissions for most of the 187 air toxics, although the data are less reliable than the inventory for the six criteria pollutants.

  • Air quality and exposure modeling. Exposure assessment of average or cumulative exposures may miss significant acute exposures…NATA does not provide estimates of ingestion risks (which are important for certain air toxics like mercury and lead)

  • Health and environmental effects estimation…characterizing the health effects of air toxics at ambient levels can be subject to a very high level of uncertainty and therefore more difficult for use in economic benefits assessments.

  • Economic valuation…Currently benefits are estimated by aggregating reduced mortality risks to an expected number of “deaths avoided” which are then multiplied by an aggregate willingness-to-pay (WTP) figure called the “value of a statistical life” (VSL)

  • Efficiency vs. Distributional Considerations…protecting the most exposed individuals rather than maximizing risk reduction over the entire exposed population may be the guiding objective”


  • “A clear definition of the purpose(s) of HAPs benefits analysis to frame long-term research priorities is needed

  • Grouping by emissions sources would address more closely the issue of hotspots or highly exposed populations

  • accounting for the heterogeneity in temporal and spatial distribution, specifically for emissions and receptors (e.g., children and other vulnerable populations) is critical for benefits analysis.

  • The National Health and Nutrition Examination Survey work on exposure distributions could be used to inform both exposures and health endpoints

  • Analytical methods to define and measure equity considerations should be better supported.

  • critical need to improve dose-response estimations

  • More research on surveillance and bio-monitoring is needed

  • More support is needed for research on the use of predictive biomarkers of exposure and health effects would allow for an early measurement of the impact in reduction of air toxics”

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