Estimating Mortality Risk Reduction and Economic Benefits from Controlling Ozone Air Pollution (2008) / Chapter Skim
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2 Overview of Ambient-Ozone Standards Development and Benefits Assessment
2 Overview of Ambient-Ozone Standards Development and Benefits Assessment
Pages 23-47
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SETTING NATIONAL AMBIENT AIR QUALITY STANDARDS FOR OZONE Beginning in 1970, the U.S. Clean Air Act (CAA)
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. As illustrated in Figure 2-1, under the 1997 NAAQS, ozone nonattainment has occurred largely in heavily populated areas east of the Mississippi River, 1 In December 2006, EPA indicated that after the current ozone NAAQS review process, it would no longer use the historical terminology of criteria document to summarize the science and staff paper to summarize staff risk assessment and recommendations to the administrator.
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1979 Ozone 0.12 ppm 1h More than 1 d/y with Move to ozone-specific effects; three clinical studies found maximal hourly reduction in pulmonary function or symptoms as having lowest average above effect level in humans at 0.15-0.3 ppm with evidence of lower 0.12 ppm effect levels in animals (Bachmann 2007) 1993 Ozone Determination that no change was necessary 1997 Ozone 0.08 ppm 8h Annual 4th-highest Many new studies over a decade found effects at daily maximal 8-h concentrations below 1979 standard with increased importance average concentration, of 6-8-h exposures; key studies found lung-function averaged over 3 y decrements, respiratory symptoms, increased sensitivity to irritants, indicators of pulmonary inflammation increasing across range of 0.08, 0.1, and 0.12 pm for 6- to 8-h exposures with subjects engaged in intermittent exercise; numerous epidemiologic studies found increased hospital admissions and emergency-room visits for respiratory causes attributed primarily to ozone; proposal highlighted risk assessment for children (nine-city)
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26 FIGURE 2-1 Counties violating 1997 primary 8-h NAAQS for ozone and other photochemical oxidants. Source: EPA 2007d.
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. Defining a PRB is unnecessary for establishing a level above which ozone is harmful to human health or for estimating changes due to a spe cific regulatory action, nor is it needed for quantifying human health re sponses to short-term ozone levels or monetizing risk changes in response to ozone changes, which are the primary foci of this study.
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28 FIGURE 2-2 Counties with monitors readings that would violate alternate 8-h ozone standards of 0.070 and 0.075 ppm proposed by EPA in June 2007 (on basis of 2003-2005 monitoring data)
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The likelihood of poor air quality in turn sets off broad-based publicinformation efforts to alert residents, especially such sensitive populations as the elderly or asthmatic, to restrict activity that might increase exposure. In the case of ozone, regulatory actions at state and federal levels have taken many forms and have resulted in controls on emissions of volatile organic compounds and nitrogen oxides -- the two primary precursors of ozone and other photochemical oxidants -- from fuels, on-road and nonroad engines, electricpower facilities, manufacturing facilities, consumer products (such as paints)
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Recent Scientific Conclusions About Risks Posed by Ozone Exposure Overall, extensive toxicologic, epidemiologic, and clinical research on the effects of exposure to ozone has yielded strong evidence of effects on respiratory end points at or near current regulatory levels, and in a variety of populations. However, clinical studies have shown substantial variability in individual responses; even sensitive populations, such as asthmatics, exhibit a range of responses and nonresponse (EPA 2006a)
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further concludes that there is clear and convincing evidence of causality for lung function decrements in healthy children under moderate exertion for 8-hr average ozone exposures. We also judge that there is strong evidence for a causal relationship between respiratory symptoms in asthmatic children and ozone exposures and between hospital admissions for respiratory causes and ambient ozone exposures.
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. Those actions were justified largely by cost-benefit analyses based on the substantial potential mortality benefits estimated from the ACS study and later reanalyses and extended analyses (Krewski et al.
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Those considerations caused EPA to fund of studies of the short-term mortality effects of ozone that are a primary focus of the present committee's review. REGULATORY BENEFITS ASSESSMENT FOR SETTING AND IMPLEMENTING NATIONAL AMBIENT AIR QUALITY STANDARDS Quantitative assessment of the potential health benefits of actions planned to improve air quality has become a central component of regulatory impact analysis in the United States and other countries.
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Concepts of Economic Valuation of Mortality Risk Reduction for Regulatory Benefits Assessment A charge to the present committee is to address the quantification and economic valuation of mortality-risk reductions in the context of cost-benefit analysis. Cost-benefit analysis is the comparison of a monetary measure of the welfare gain for those who benefit from a policy or program with a monetary measure of the welfare loss for those who are harmed (that is, who incur costs)
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His analysis showed that if people's altruism toward others is general regarding the others' enjoyment and satisfaction, there is no need to add WTP values for others' mortality risk reductions to WTP for people's own mortality risk reduction in a cost-benefit analysis. It is only in the case of what Jones-Lee calls "paternalistic altruism" that an argument could be made for adding WTP values that a person has for another's mortality risk reduction in a cost-benefit analysis.
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There are many unanswered questions about how the VSL might vary in different contexts and in populations with different characteristics. One important and controversial question is whether WTP for mortality-risk reduction is expected to be proportional to remaining life expectancy.
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Of course, the specific people whose deaths are prevented cannot be identified, and remaining life expectancy of any specific person is not known, but estimates can be made by using pollution-related risk estimates for age groups and using life tables that give average remaining life expectancies of people of different ages. This is discussed further in Chapter 4.
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• Second, and perhaps more important, an RIA is prepared for every major EPA rule designed to reduce emissions of NAAQS pollutants or their precursors from mobile, stationary, and other sources. Although the RIA does not have a statutory role in EPA's setting of the standard, the CAA provisions that authorize actions to meet a standard normally do include cost among the criteria to be considered, so the cost and benefit analyses conducted in an RIA often are important in determining which actions to reduce emissions may be most effective in improving health at the lowest cost.
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For example, assume that a pollution-reduction program costs $10 million and has two benefits: benefits to the commercial forest industry that can be quantified and benefits to forest ecosystems that cannot be quantified. If the benefit to the commercial forest industry is estimated at $7 million, the benefit to forest ecosystems would have to be worth more than $3 million for the total benefits to exceed the costs.
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discusses the quantification and economic valuation of mortality risk reductions. OMB does not require the use of any specific measure of effectiveness, such as lives saved or life-years saved, but encourages agencies to report results using multiple metrics that may provide different insights and perspectives.
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. ENVIRONMENTAL PROTECTION AGENCY'S APPROACH TO ESTIMATING OZONE MORTALITY IMPACTS AND VALUING MORTALITY RISK REDUCTION3 Several examples show how EPA's benefits assessments include quantified and monetized ozone health benefits.
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EPA's current primary approach for economic valuation of mortality risk reductions is a variation on their long-standing approach of using the same VSL for all annual mortality reductions. Starting with the RIA for the Clean Air Interstate Rule (EPA, 2005a)
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They further concluded that results in the empirical literature are also insufficient at this time to provide a basis for making quantitative adjustments to VSL according to the age or remaining life expectancy of the population at risk. In addition, they concluded that the empirical literature provides no support for the assumption implicit in the use of a constant VSLY that WTP for mortality risk reduction is proportional to remaining life expectancy.
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A few FDA analyses have presented alterna tive estimates of the value of mortality risk reductions using VSLY as well as VSL estimates [e.g., 68 Fed.
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. California The state of California conducted a benefits assessment during the process of making their latest revisions to the state ambient ozone standard in 2004.
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VSL estimates from the working age population were thus adjusted downward to reflect the age distribution of nonaccidental causes of mortality that are associated with air pollution. Health Canada is currently planning to update their procedures for selecting values for mortality risk reductions.
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. The ExternE authors converted this 10-year mortality risk change to its equivalent in increased life expectancy for each age/gender cohort and calculated the VSLY implicit in the WTP responses.
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