An NRC committee will evaluate the scientific and technical bases of approaches used by EPA for estimating ozone mortality risk reduction and associated benefits of health-based standards over time. It will assess methods for estimating reductions in premature mortality due to diminished short-term exposure to ozone, increases in life expectancy, economic valuation of the increased life expectancy, and associated uncertainties and their general implications for decision making. In addition, the committee will recommend approaches for characterizing and communicating each of those aspects in regulatory health benefit analyses. Specifically, the committee's evaluation will include consideration of the following aspects:o The committee will take into account the relevant reports of past NRC and IOM committees, as well as risk assessment for particulate matter (PM) carried out by the EPA.o Relative contributions of recent studies (especially those published since 2003) for characterizing the size of the ozone-mortality effect in the context of benefits analysis. o Potential implications of methods used in the recent studies on reported benefits estimates (e.g., selection of data considered in the studies, selection of mortality effect estimates from within the considered data, control for effect moderators [such as temporal trends], treatment of potential publication bias, or other factors). Include consideration of the likely direction and magnitude of any influences that may result from choice of methods.o Available data and methods to account for the relative roles of potential confounders, such as copollutants, and the influence they have on estimates of ozone mortality effects. o The most appropriate exposure metrics for use in developing a concentration-response function designed to quantify the number of premature mortalities associated with specific regulatory options. How does the choice of exposure metrics affect benefits estimation? Include consideration of dose estimation, particularly for sensitive groups.o Adequacy of a basis for estimating the likely impact on life expectancy from reductions in short-term daily exposures to ozone. If there is an adequate basis, provide specific recommendations, if possible, on approaches for how EPA should quantitatively express the magnitude and associated uncertainties of this impact.o Strengths and weaknesses of the data, methods, and assumptions employed by EPA for sensitivity analyses in the context of an ozone-mortality effect relationship.o Quantitative approaches for estimating the degree of uncertainty in premature mortality estimates associated with reductions in ambient ozone concentrations. Aspects to be considered will include both parameter and model uncertainty in the concentration-response function, differences within and between the epidemiologic and toxicologic data bases, reliance on surrogates of personal exposure, identification of sensitive populations, and other factors. Identify methods of presenting the quantitative uncertainty estimates. o Scientific approaches for assigning economic values to reductions in mortality risk when the reduction in risk results in changes in life-expectancy of varying lengths. If there is an adequate basis for quantifying those changes, consider: - How the current understanding of premature mortality associated with short-term ozone exposure informs the most appropriate scientific approach to economic valuation of benefits. Consider methods to account for baseline health status, baseline and the magnitude of the change in life-expectancy, differences across various sectors of the population, uncertainty, and other relevant factors. - Applicability of the economics literature on mortality risk valuation and the associated methodologies developed for economic valuation of premature mortality reductions in the context of the health effects of ozone. - Issues that are specific to ozone and those which may be more broadly applicable to benefits assessments for other risk reduction strategies. o Major gaps in knowledge about ozone-mortality benefits analysis and the most promising research strategies to close those gaps. Identify any additional data, analyses, or research needed to separate the relative contributions of ozone and other gaseous or particulate components of the air pollution mix to the total short term premature mortality effect documented in the literature. In assessing the methods for estimating ozone mortality risk, the committee will not develop its own estimate of such risk. In assessing the methods for economic valuation of reductions in mortality risk, the committee will not itself judge the appropriateness of values assigned to a life saved or life years added.The project is sponsored by the Environmental Protection Agency.The approximate start date for the project is September 21, 2006.NOTE: The project duration has been extended and a prepublication version of the report is currently expected to be released by March 31, 2008.