How have you addressed and communicated uncertainty in risk assessments?

Please discuss the adequacy of default assumption choices, and efforts to use alternatives to these default assumptions.

Please describe the ways in which children and potentially unique or vulnerable populations are specifically considered in your office’s risk assessments. Please provide examples.


Current Practice
  • Statutory basis/current approach and paradigms for risk assessment (specific to each program office)

    • Examples and best practices

    • Gaps and problems

  • Uncertainty analysis

    • Examples

    • Communication of risk and uncertainty

  • Sensitive and vulnerable subpopulations (e.g., children, elderly, tribes, endangered species)

    • Examples of physical attributes and unique exposures that impact risk

    • Problems and challenges

  • Challenges for risk assessment in a regulatory process

    • Examples

    • Problems and challenges

General Comment

The 2004 Agency document “An Examination of EPA Risk Assessment Principles and Practices” (EPA 2004a) provides a good resource for understanding the Agency as well as OAR’s approach to risk assessment. Consistent to the focus of the NAS committee charge this response does not address ecological risk assessment. Protection of ecosystems from adverse impacts from of air pollution is an important mission of our Office and we could provide additional information in this area if requested.

There are two programs within OAR that best illustrate the use of risk assessment in our Office. First, are assessment activities that support the development of national ambient air quality standards (NAAQS) for the 6 “criteria” air pollutants, and, second, those conducted in consideration of emissions controls for hazardous air pollutants (HAPs or air toxics).

National Ambient Air Quality Standards (NAAQS)

The “criteria” air pollutants are the six pollutants—ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide and lead—the presence of which in the ambient air results from numerous or diverse sources, and for which there are established public health concerns at historic ambient levels. These pollutants have been extensively studied

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