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Health Benefits Analyses: EPA Case Studies

The committee reviewed the health benefits analyses contained in the regulatory impact assessments (RIAs) prepared for the following EPA rule-makings: (1) “Particulate Matter and Ozone National Ambient Air Quality Standards” (EPA 1997), (2) “Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements” (EPA 1999a), and (3) “Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements” (EPA 2000a). The committee also reviewed the health benefits analysis completed for the EPA prospective analysis of the benefits and costs of the 1990 Clean Air Act Amendments (CAAA) (EPA 1999b), which used methods similar to those used in the other EPA analyses reviewed by the committee. Critical elements of the analyses are summarized in Tables 2-1 and 2-5, and the sections that follow provide a brief summary of the EPA analyses to aid the reader in understanding the critiques in the chapters that follow. Although the analyses provide methods and estimates for welfare benefits (all benefits other than health, such as improvements in visibility), the focus of the following discussion is human health benefits.

PARTICULATE MATTER AND OZONE NATIONAL AMBIENT AIR QUALITY STANDARDS

EPA is required by the Clean Air Act (CAA) to review National Ambient Air Quality Standards (NAAQS) at least once every 5 years and



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Estimating the Public Health Benefits of Proposed Air Pollution Regulations 2 Health Benefits Analyses: EPA Case Studies The committee reviewed the health benefits analyses contained in the regulatory impact assessments (RIAs) prepared for the following EPA rule-makings: (1) “Particulate Matter and Ozone National Ambient Air Quality Standards” (EPA 1997), (2) “Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements” (EPA 1999a), and (3) “Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements” (EPA 2000a). The committee also reviewed the health benefits analysis completed for the EPA prospective analysis of the benefits and costs of the 1990 Clean Air Act Amendments (CAAA) (EPA 1999b), which used methods similar to those used in the other EPA analyses reviewed by the committee. Critical elements of the analyses are summarized in Tables 2-1 and 2-5, and the sections that follow provide a brief summary of the EPA analyses to aid the reader in understanding the critiques in the chapters that follow. Although the analyses provide methods and estimates for welfare benefits (all benefits other than health, such as improvements in visibility), the focus of the following discussion is human health benefits. PARTICULATE MATTER AND OZONE NATIONAL AMBIENT AIR QUALITY STANDARDS EPA is required by the Clean Air Act (CAA) to review National Ambient Air Quality Standards (NAAQS) at least once every 5 years and

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations to revise standards when necessary to protect the public health and the environment (EPA 1997). By the mid-1990s, scientific evidence suggested that the standards for both particulate matter (PM) and ozone needed revision. Accordingly, EPA proposed new PM and ozone NAAQS and released an RIA evaluating the benefits and costs of the proposed standards (EPA 1997). The proposed PM and ozone standards were evaluated in the same RIA because of the similarities in precursors, sources, atmospheric residence times, and atmospheric chemistry. The RIA also included an assessment of a proposed regional haze rule; however, the committee focused on the health benefits analyses conducted for the PM and ozone standards because they were more closely related to its task. The proposed standards that were evaluated were (1) an annual mean PM2.5 standard of 15 micrograms per cubic meter (µg/m3) and a 98th percentile 24-hour (hr) average of 65 µg/m3 in conjunction with an annual mean PM10 standard of 50 µg/m3 and 99th percentile 24-hr average of 150 µg/m3, and (2) an 8-hr ozone standard of 0.08 parts per million (ppm) based on the fourth highest average daily maximum.1 Two alternative standards were also evaluated for PM2.5 and ozone. EPA evaluated a partial-attainment scenario that accounted for areas that would not be able to meet the proposed standards or alternatives based on current control technologies and a full-attainment scenario that assumed no residual nonattainment. EPA noted that more uncertainty was associated with the estimates for the full-attainment scenario because attainment was based on development of new technologies. The benefits were estimated in the year 2010 because EPA assumed that the majority of CAA-mandated controls would be achieved by that date. EPA used a six-step approach for estimating the benefits for the proposed and alternative PM and ozone standards. In the first step, EPA developed an emissions inventory for the year 2010. The inventory included estimates for volatile organic compounds (VOCs), nitrogen oxides (NOx), sulfur dioxide (SO2), secondary organic aerosols, PM2.5, PM10, and ammonia (NH3). To construct the 2010 inventory, EPA first generated a 1990 emissions inventory using source-specific emissions factors and activity levels, such as fuel consumed by electric utilities or miles traveled by motor vehicles. The 2010 emissions inventory was then projected using the 1990 1   PM10 refers to PM with an aerodynamic diameter of 10 µm or less, and PM2.5 refers to PM with an aerodynamic diameter of 2.5 µm or less.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations emissions inventory, sector-specific growth assumptions, and source-specific assumptions regarding future CAA-mandated controls expected to be achieved by 2010. In the second step, county-level baseline air-quality data for the continental United States were generated. For PM, a source-receptor matrix was first generated using the phase 2 climatological regional dispersion model (CRDM). Because the model was shown to overestimate the contribution of fugitive dust to fine PM, the source-receptor matrix was adjusted, and monitoring data were used to calibrate the matrix. Baseline annual mean PM10 and PM2.5 estimates for 2010 were then generated using the 2010 emissions data and the source-receptor matrix. PM estimates for nonmonitored counties were generated on the basis of the more complete data sets for the monitored counties. Peak-to-mean ratios were used to generate 24-hr averages. For ozone, a regional oxidant modeling (ROM) extrapolation method was used to generate county-level baseline air-quality data for ozone. Ozone air-quality monitoring data from 1990 and ROM air-quality modeling results for 2007 were used to generate ozone air-quality data for 2007. The data for 2007 were then extrapolated using 2010 emissions data and ozone modeling and monitoring data to give 2010 baseline ozone air-quality data. Data for nonmonitored counties were generated by interpolating data from surrounding monitored counties, assuming that the entire county population experienced the air pollution concentration estimated at the geographic center (or centroid) of the county. In the third step, EPA used the PM and ozone baseline air-quality data to identify counties that would exceed the proposed or alternative standards. In the fourth step, EPA selected control strategies to implement in the nonattainment counties and then estimated the potential costs and economic impacts of the proposed and alternative standards. In the fifth step, EPA estimated the post-control air-quality data on the basis of the control strategies selected in step four. For the partial-attainment scenario, EPA used the source-receptor matrix to estimate PM air-quality data and a quadratic rollback procedure to estimate ozone air-quality data. For the full-attainment scenario, a proportional and a quadratic rollback procedure were used to estimate PM and ozone air quality, respectively.2 2   Rollback procedures scale an exposure estimate by the changes modeled for the emissions estimates. Therefore, proportional rollback assumes that concentra-

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations In the sixth step, EPA estimated the human health benefits resulting from implementation of the proposed or alternative standards for each county in the continental United States and then summed across counties to give the national estimates. EPA estimated the reductions in the incidences of a number of human health effects (see Table 2-1). Although EPA indicated that a few additional health effects were quantified, the results were not included in the analysis. Human health effects that could not be quantified but were associated with exposure to the pollutants were also listed. The human health benefits were estimated on the basis of the differences in pre- and post-control air-quality data and quantitative concentration-response functions derived from the epidemiological literature. The Pope et al. (1995) study was used to determine mortality reductions resulting from PM reductions. For ozone, a meta-analysis of nine epidemiological studies was used to determine mortality reductions resulting from ozone decreases. Clinical studies were used to support data for effects of ozone exposure. One important assumption made in this analysis was that the health benefits were realized in the year in which the exposure reductions occurred. The benefits were monetized to derive a total benefits estimate that could be compared with the cost estimate. The analytical uncertainty was partially reflected by providing a plausible range of benefits estimates.3 For the high-end estimates, an effects threshold of 12 µg/m3 was assumed for PM2.5-related long-term mortality, mortality benefits (deaths avoided) were estimated for reductions in ozone concentration using a meta-analysis of nine epidemiological studies, ancillary PM benefits were included in the ozone benefits estimates,4 and an approach based on the value of a statistical life (VSL) was used to monetize the mortality benefits. For the low-end estimate, an effects threshold of 15 µg/m3 was assumed for all PM2.5-related health outcomes, no mortality benefits were estimated for reductions in ozone concentration, no ancillary PM benefits were included in the ozone benefits analysis, and an approach based on the value of a statistical life year (VSLY) was used to value the     tions and emissions are proportionally related, and a quadratic rollback assumes a quadratic relationship between emissions and concentrations. 3   EPA noted that the plausible ranges provided were not equivalent to upper and lower statistical confidence bounds. 4   Reduction in precursors resulting from measures to control ozone formation will also result in reduction of PM. The benefits derived from the reduction in PM in this case are referred to as ancillary PM benefits.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-1 Elements of Selected EPA Benefits Analyses Parameters PM and Ozone NAAQS (EPA 1997)a Tier 2 Emissions and Gasoline Sulfur Standards (EPA 1999a) Heavy-Duty Engine and Diesel-Fuel Standards (EPA 2000a) Year in which benefits evaluated (justification) 2010 (anticipated date when standards will be implemented) 2030 (anticipated date when fleet will be fully turned over) 2030 (anticipated date when fleet will be fully turned over) Scenarios Evaluated partial and full attainment of standards for three PM and ozone alternatives Evaluated conditions with and without the standards being proposed Evaluated conditions with and without the standards being proposed Pollutants modeled and methods used for air-quality modeling for benefits analysis Ozone – quadratic air-quality rollback procedures (partial and full attainment scenarios) based primarily on regional oxidant model and monitoring data PM – source-receptor matrix based on climatological regional dispersion model (partial-attainment scenario); proportional rollback procedure (full-attainment scenario) Ozone – regional-scale version of the urban airshed model PM – source-receptor matrix based on the climatological regional dispersion model Ozone – regional-scale version of the urban airshed model-variable grid (note: modeling results for western U.S. not used in benefits analysis) PM – national-scale version of the regulatory modeling system for aerosols and deposition Geographic scale of models used to estimate air quality Ozone – 18-km grid squares or county level (size varies) PM – county level (size varies) Ozone – 12 or 36-km grid squares for eastern U.S. and 56-km grid squares for western U.S. PM – county level (size varies) Ozone – 12 or 36-km grid squares for eastern U.S. (note: western U.S. not included in analysis) PM – 36-km grid squares

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations Health outcomes quantified and monetizedb Ozone – mortality; hospital admissions (all respiratory, pneumonia, COPD, and emergency dept.visits for asthma); acute respiratory symptoms (asthma attacks and minor restricted-activity days); mortality from air toxics PM – mortality (short- and long-term); bronchitis (chronic and acute); hospital admissions (all respiratory [all respiratory, pneumonia, and COPD], congestive heart failure, and ischemic heart disease), lower and upper (shortness of breath, asthma attacks) respiratory symptoms; work-loss days; minor restricted-activity days Ozone – chronic asthma; minor restricted-activity days and acute respiratory symptoms; hospital admissions (respiratory and cardiovascular); emergency room visits for asthma PM – premature mortality; bronchitis (chronic and acute); hospital admissions (respiratory and cardiovascular); emergency room visits for asthma; lower and upper respiratory illness; shortness of breath; minor restricted-activity days and acute respiratory symptoms; work-loss days Ozone – minor restricted-activity days; hospital admissions (respiratory and cardiovascular); emergency room visits for asthma; asthma attacks PM – premature mortality; bronchitis (acute and chronic); hospital admissions (respiratory and cardiovascular); emergency room visits for asthma; asthma attacks; lower and upper respiratory illness; minor restricted-activity days; work-loss days Concentration-response function used for primary estimates of mortality benefits Pope et al. (1995) Pope et al. (1995) Krewski et al. (2000), a re-analysis of the Pope et al. (1995) study Threshold assumptions High-end estimate of benefits assumed 12 µg/m3 mean threshold for PM2.5-related long-term mortality; low-end estimate of benefits assumed 15 µg/m3 threshold for all PM-related health outcomes No thresholds above background concentrations assumed for modeled health effects No thresholds above background concentrations assumed for modeled health effects

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations Parameters PM and Ozone NAAQS (EPA 1997)a Tier 2 Emissions and Gasoline Sulfur Standards (EPA 1999a) Heavy-Duty Engine and Diesel-Fuel Standards (EPA 2000a) Lag-time assumptions No lag times assumed; benefits assumed to occur in the year that exposure is reduced 5-year lag structure assumed for PM-related premature deaths with 25% in years 1 and 2 and 16.7% in years 3, 4, and 5 5-year lag structure assumed for PM-related premature deaths with 25% in years 1 and 2 and 16.7% in years 3, 4, and 5 Quantification of uncertainty 1. Presented plausible range of benefits estimates calculated by varying key assumptions in analysis; estimates are not upper and lower statistical bounds 2. Conducted several sensitivity analyses, such as one to evaluate using a proportional rollback procedure to estimate ozone air quality 1. Provided alternative calculations of primary benefit estimates by varying key assumptions 2. Conducted sensitivity analysis for alternative lag structures and PM threshold assumptions 1. Provided alternative calculations of primary benefit estimates by varying key assumptions 2. Conducted sensitivity analysis for alternative lag structures and PM threshold assumptions Study populations evaluated for health outcomes Majority of benefits appear to be estimated for adult population; however, PM- and ozone-related “all respiratory” hospital admissions were estimated for elderly adults (over 65 yr) Majority of benefits estimated for adult populations; PM-related acute bronchitis estimated for children aged 8 to12, lower respiratory symptoms estimated for children aged 7 to 14, upper respiratory symptoms estimated for children aged 9 to 11, and shortness of breath estimated for African American children aged 7 to 12; ozone-related chronic asthma estimated for adult males Majority of benefits estimated for adult populations; PM-related cardiovascular, pneumonia, and COPD hospital admissions estimated for elderly population (over 64 yr) and PM-related acute bronchitis and upper and lower respiratory symptoms estimated for children (ages between 7 and 14 yr) with upper respiratory symptoms estimated specifically for asthmatic children

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations aThis regulatory impact assessment (RIA) also included an evaluation of a proposed regional haze rule; however, because the PM and ozone analyses were more closely related to the committee’s task, the committee focused on these analyses. bMany health effects were listed as unquantified for ozone and PM in all three RIAs. Unquantified health effects were also listed for carbon monoxide (CO) and hazardous air pollutants in Tier 2 rule-making, and for sulfur dioxide, nitrogen oxides, CO, and nonmethane hydrocarbons in heavy-duty engine and diesel-fuel rule-making. Abbreviations: PM, particulate matter; NAAQS, National Ambient Air Quality Standards; COPD, chronic obstructive pulmonary disease.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations mortality benefits. EPA also indicated that several sensitivity analyses of key assumptions were conducted. One such analysis investigated alternative rollback procedures to estimate post-control ozone air quality. EPA also qualitatively discussed uncertainties relevant to various phases of the analyses and provided an opinion on whether the uncertainty would lead to an overestimate (positive bias) or an underestimate (negative bias) of results. Annual benefits (avoided cases of morbidity and mortality) of the proposed ozone and PM2.5 standards are shown in Table 2-2 for the partial-attainment scenario in 2010. Annual benefits of the proposed ozone standard are incremental to the current ozone standard, and those of the proposed PM2.5 standard are incremental to the current ozone and PM10 standards. Monetized values are also provided. TIER 2 MOTOR VEHICLE EMISSIONS STANDARDS AND GASOLINE SULFUR CONTROL REQUIREMENTS The Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements Rule (Tier 2 rule) sets new federal motor-vehicle emissions standards and establishes limits on sulfur concentrations in gasoline (EPA 1999a). The emissions standards apply to all passenger cars, light trucks, and medium-duty passenger vehicles, which include sport utility vehicles (SUVs) and passenger vans. The standards are designed to limit emissions, such as NOx, that contribute to ozone and PM formation and, therefore, will help states meet the ozone and PM NAAQS. Full compliance with the emissions standards should be achieved by 2009, with phase-in periods dependent on vehicle class. Full compliance with the gasoline sulfur limits should be achieved by 2006. The benefits of the rule were assessed for the year 2030, when full implementation is expected through turnover of the existing vehicle fleet. EPA used a four-step approach for the Tier 2 benefits analysis. First, reductions in motor-vehicle emissions anticipated from the standards were used to estimate the impact on emissions inventories of NOx, SO2, nonmethane hydrocarbons (NMHCs), PM2.5, PM10, and NH3 for the continental United States in 2030.5 Compliance assumptions were not clearly stated in the discussion of the benefits analysis. 5   The RIA appeared to equate nonmethane hydrocarbons (NMHCs) with VOCs as this class of compounds was later listed instead of NMHCs.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-2 Annual Benefits (Avoided Cases of Morbidity and Mortality and Monetized Value) of the Proposed Ozone and PM2.5 Standards for the Partial-Attainment Scenario in 2010 Health Outcome Avoided Cases (Low- to High-End Estimates) Monetized Value (1990$ in millions) Ancillary PM Benefits Included in Ozone High-End Estimatea PM-Related Outcomes Mortality 3,300-15,600b 1,800-75,100 80 ($400); 250 ($1,210)c Chronic bronchitis 45,000-75,000 11,700-19,400 530 ($140) Hospital admissions All respiratory illnesses (all ages) 3,600-5,700 42-72 90 ($1) Congestive heart failure 1,200-2,100 30-35 20 ($0) Ischemic heart disease 1,200-2,400 30-49 20 ($0) Acute bronchitis 12,000-20,000 1 400 ($0) Lower respiratory symptoms 179,000-299,000 2-4 4,670 ($0) Upper respiratory symptoms 36,000-60,000 1 430 ($0) Work-loss days 1,900,000-3,148,000 156-261 50,440 ($4) Minor restricted-activity days 15,697,000-26,128,000 600-1,000 420,300 ($16) Ozone-Related Outcomes Mortality 0-80 0-380 — Hospital admissions All respiratory illnesses (all ages) 300d 4 — Acute respiratory symptoms (any of 19) 29,840d 1 — Mortality from air toxics 1d 6 — aAncillary PM benefits are those benefits derived from PM reductions due ozone control measures. Avoided cases are provided with monetary estimates provided in parentheses in millions of 1990 dollars. bEstimates were designated as mortality estimates for short-term exposure; however, the low-end estimate represents short-term exposure and the 15 µg/m3 threshold, and the high-end estimate represents long-term exposure and the 12 µg/m3 threshold (B. Hubbell, EPA, personal communication, June 4, 2002). cMortality estimate for short-term exposure; mortality estimate for long-term exposure. dRange not provided. Source: Data from EPA 1997.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations Second, air-quality modeling of ozone and PM was conducted for a base year (1996) and two future scenarios: 2030 with and without the standards implemented. Ambient ozone was modeled using the urban airshed model variable (UAM-V). Monitoring data from 1996 were used to calibrate the model, and data for nonmonitored areas were generated by interpolating values from nearby monitoring sites. The eastern and western United States were modeled separately with finer resolution used in the eastern United States (12- or 36-km grids versus 56-km grids). Two simulation periods (July 12-24, 1995, and July 5-15, 1995, for the eastern United States and July 5-15, 1996, and July 18-31, 1996, for the western United States) were used to generate the ozone data for the benefits analysis. Similar to the analysis for the PM NAAQS, ambient PM2.5 and PM10 were modeled using a source-receptor matrix based on CRDM. The source-receptor matrix was adjusted for the overestimate of the contribution of fugitive dust to PM2.5 and then calibrated using monitoring data. The criteria air pollutant modeling system (CAPMS) was used to estimate health benefits on the basis of the projected changes in ambient concentrations of ozone and PM and concentration-response functions derived from epidemiological studies. Many health outcomes were quantified (see Table 2-1), and many health outcomes were listed as “unquantified effects” for ozone and PM, as well as for carbon monoxide (CO) and hazardous air pollutants (HAPs). EPA noted that the effects for CO and HAPs were not quantified because no appropriate air-quality models were available. To translate relative risk concentration-response functions into absolute numbers of cases, baseline incidences of each health outcome were estimated within specific age groups. A single concentration-response function for each outcome was applied to the entire country. The Pope et al. (1995) study was used to estimate PM-related premature mortality. No mortality estimates were calculated for ozone because they were assumed to be accounted for in the PM estimates. No thresholds above background concentrations were assumed when modeling the health effects. A 5-year lag structure was assumed for PM-related premature mortality (25% in the first and second years and 16.7% in each of the remaining 3 years). In the final step, the benefits were monetized for comparison with the cost estimates. EPA used the VSL approach to monetize the premature mortality estimates. The uncertainty in the analysis was evaluated by identifying key assumptions and presenting alternative calculations. For example, alternative calculations for premature mortality were presented using the Dockery et

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-3 Annual Health Benefits (Avoided Cases of Mortality and Morbidity and Monetized Value) for Tier 2 Regulation in 2030 Health Outcome Avoided Casesa Monetized Benefit (1997$ in millions)b PM-Related Health Outcomes Premature mortality (adults, ages 30 and over) 4,300 (2,700-5,900) 23,380 Chronic bronchitis 2,300 (600-4,100) 730 Hospital admissions   Respiratory causes 1,200 (400-2,100) 10 Cardiovascular causes 500 (100-1,100) 10 Emergency room visits for asthma 900 (400-1,400) <1 Acute bronchitis (children, ages 8-12) 7,900 (0-16,300) <1 Lower respiratory symptoms (children, ages 7-14) 87,100 (39,900-131,100) <5 Upper respiratory symptoms (children with asthma, ages 9-11) 86,500 (25,500-144,600) <5 Shortness of breath (African Americans with asthma, ages 7-12) 17,400 (4,700-29,500) <1 Work-loss days (adults, ages 18-65) 682,900 (597,800-771,800) 70 Minor restricted-activity days and acute respiratory symptoms 3,628,500 (3,034,100-4,177,200) 170 Ozone-Related Health Outcomes Chronic asthma (adult males, ages 27 and over) 400 (100-800) 10 Hospital admissions   Respiratory causes 1,000 (200-1,800) 10 Cardiovascular causes 300 (0-500) <5 Emergency-room visits for asthma 400 (100-600) <1 Minor restricted-activity days and acute respiratory symptoms 2,226,500 (1,014,400-3,414,800) 100 Decreased worker productivity (adult working population) Not reported 140 aMean value provided with 5th and 95th percentile values shown in parentheses rounded to the nearest 100. bMean value of monetized value provided for reference. Source: Adapted from EPA 1999a,c.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations The benefits of the HD engine and diesel-fuel rule were evaluated using the general procedure used for the Tier 2 rule. However, several aspects differ among the analyses, such as air-quality models used, health outcomes evaluated, concentration-response functions selected, and valuation techniques used. Similarities and differences are highlighted in the following discussion. Similar to the Tier 2 benefits analysis, a four-step approach was used to estimate benefits for the HD engine and diesel-fuel rule. First, emissions inventories were developed for two scenarios for the year 2030—a baseline scenario in which the rule was not implemented and a control scenario in which the rule was fully implemented. The year 2030 was chosen because it provided “a snapshot of benefits and costs in a future year in which the heavy duty fleet consists almost entirely of vehicles and fuels meeting” the HD engine and diesel-fuel standards. Emissions estimates were developed for NOx, NMHC, SO2, and PM. Compliance assumptions were not clearly presented in the discussion of the benefits analysis. Second, ambient air concentrations of ozone and PM (PM10 and PM2.5) across the continental United States were modeled for a base-year (1996) and for the baseline and control scenarios in 2030. Both air-quality models used for the analysis simulated the physical and chemical processes in the atmosphere that affect pollution transport and transformation and provided temporal and spatial concentration estimates. Inputs to the models included emissions inventories, meteorological data, and land-use information. Similar to the Tier 2 analysis, ambient ozone concentrations were estimated using a regional-scale version of the urban airshed model-variable grid (UAM-V). However, for the benefits analysis of the HD engine and diesel-fuel rule, EPA did not include the modeling results for the western United States because of poor model performance in that region (the model significantly underestimated observed concentrations). Hourly ozone concentrations were simulated within 12- or 36-km grid squares covering the eastern United States for three brief periods in the summer (June 12-24, July 5-15, and August 7-21, 1995), which were selected because they represented a recent time period and “contained several periods of elevated ozone over the Eastern U.S.” The modeling results were corrected using calibration factors developed from comparison of modeled and monitor data for the base-year of 1996. The modeling results were extrapolated to a 5-month ozone “season” (May-September). Ozone data for nonmonitored areas were obtained by interpolation of data from nearby monitoring sites. Air-quality estimates for PM were developed using a national-scale

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations version of the regulatory model system for aerosols and dispersion (REMSAD). This modeling procedure differed from that used for the Tier 2 analysis. Three-hour average PM concentrations were simulated for a full year within 36-km square grids for the continental United States. PM species modeled included primary coarse fraction PM (2.5 to 10 µm diameter range), primary fine particles (under 2.5 µm diameter), and several secondary fine particles, such as sulfates, nitrates, elemental carbon, and organics. All fine-particle components were summed to obtain PM2.5 estimates. Because insufficient PM2.5 monitoring data were available across the United States, the PM2.5 simulations could not be calibrated. Similar to the Tier 2 analysis, CAPMS was used to estimate health benefits on the basis of differences in ambient air concentrations in the baseline and control scenarios for 2030 and concentration-response functions derived from epidemiological studies. However, there were a few differences in health outcomes evaluated and concentration-response functions selected between the Tier 2 analysis and HD engine and diesel-fuel analysis. For example, chronic asthma and shortness of breath were not evaluated as primary health outcomes for ozone and PM, respectively; however, asthma attacks were evaluated for both ozone and PM. An adjustment was made to the estimates for minor restricted-activity days to avoid double-counting of effects. In addition, the concentration-response function used to estimate PM-related premature mortality was taken from the re-analysis of the Pope et al. (1995) study (Krewski et al. 2000). To translate relative risk concentration-response functions into absolute numbers of cases, baseline incidences of each health outcome were estimated within specific age groups. A single concentration-response function for each outcome was applied to the entire country. No thresholds above background concentrations were assumed, and a 5-year lag structure was assumed for PM-related premature mortality (25% in the first and second years and 16.7% in each of the remaining 3 years). Finally, benefits were monetized and compared with cost estimates. A VSL approach was used to monetize the mortality benefits. Estimates were not provided using a VSLY approach; however, alternative calculations were provided using an age-adjusted VSL approach. The benefits estimates for this analysis were adjusted to reflect growth in real income. Uncertainties in this analysis were evaluated using the same approach as that used in the Tier 2 analysis. Alternative calculations were presented for key assumptions and included calculations for avoided cases of prema-

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations ture mortality using an age-adjusted VSL approach, for avoided cases of chronic asthma for ozone, and for avoided cases of other health outcomes using different concentration-response or valuation functions. Sensitivity analyses were used to evaluate lag structures and threshold assumptions. Supplemental calculations were also presented for several health outcomes, such as premature mortality resulting from short-term PM or ozone exposure and infant mortality resulting from PM exposure. These supplementary estimates were not considered additive to the primary benefits estimates. The annual health benefits estimated for the HD engine and diesel-fuel regulation are summarized in Table 2-4 for the year 2030. Monetized benefits are also provided. As indicated in the table, the mortality benefits dominate the overall estimate when the benefits are monetized. PROSPECTIVE ANALYSIS OF THE 1990 CLEAN AIR ACT AMENDMENTS “The Benefits and Costs of the Clean Air Act, 1990-2010” (EPA 1999b) analyzed the benefits and costs of Titles I-V of the 1990 Clean Air Act Amendments (CAAA). Critical elements of the analysis are summarized in Table 2-5. Each title of the CAAA targets different sources or types of air pollutants. Specifically, Title I, which targets primarily stationary sources, establishes a program for meeting and maintaining the NAAQS; Title II establishes regulations for mobile sources and requirements for reformulated gasoline; Title III regulates hazardous air pollutant (HAP) emissions and defines HAPs to be regulated; Title IV establishes a program for controlling precursors of acid rain (primarily SO2 emissions from electric utilities); and Title V “requires a new permitting system for primary sources of air pollution.” The benefits and costs of Title VI, which limits the emissions of stratospheric ozone-depleting chemicals, are also reported in the study; however, they are based on a previous regulatory impact assessment (RIA), and the methods used to derive them are not discussed further here. Because each title consists of many individual rules, the analysis is much broader than in most RIAs, including those discussed in this chapter. EPA analyzed two scenarios: a pre-CAAA condition in which all pollution controls are frozen at 1990 levels of stringency and effectiveness and a

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-4 Annual Health Benefits (Avoided Cases of Morbidity and Mortality and Monetized Value) for the HD Engine and Diesel-Fuel Regulation for 2030 Health Outcome Avoided Casesa Monetized Benefit (1995$ in millions)b PM-Related Health Outcomes Premature mortality (adults, ages 30 and over) 8,300 (4,800-11,700) 62,580 Chronic bronchitis (adults, ages 26 and over) 5,500 (1,900-9,500) 2,430 Hospital admissions   Pneumonia (adults, ages 65 and over) 1,100 (600-1,600) 20 COPD (adults, ages 64 and over) 900 (200-1,600) 10 Asthma (ages 65 and younger) 900 (400-1,400) 10 Cardiovascular (adults, ages 65 and over) 2,700 (2,300-3,100) 50 Emergency room visits for asthma (ages 65 and younger) 2,100 (900-3,200) <5 Asthma attacks (all ages) 175,900 (61,000-291,900) Not monetized Acute bronchitis (children, ages 8-12) 17,600 (• •100-35,900) <5 Lower respiratory symptoms (children, ages 7-14) 192,900 (88,300-295,800) <5 Upper respiratory symptoms (children with asthma, ages 9-11) 193,400 (65,300-325,400) 10 Work-loss days (adults, ages 18-65) 1,539,400 (1,337,300-1,733,300) 160 Minor restricted-activity days (adults, ages 18-65) 7,990,400 (6,806,700-9,104,800) 430 Ozone-Related Health Outcomesc Hospital admissions   Respiratory causes (all ages) 1,200 (200-2,100) 20 Cardiac dysrhymias (all ages) 300 (0-600) <5 Emergency room visits for asthma (all ages) 300 (100-500) <1 Asthma attacks (all ages) 185,500 (70,400-305,800) Not monetized Minor restricted-activity days (adults, ages 18-65) 1,848,100 (988,600-2,706,600) 100 Decreased worker productivity (adult working population) Not reported 140 aMean value provided with 5th and 95th percentile values shown in parentheses rounded to the nearest 100. bMean value of monetized value provided for reference. The estimates have been adjusted for growth in real income. cEstimates provided are for eastern United States only. Abbreviation: COPD, chronic obstructive pulmonary disease. Source: Adapted from EPA 2000a,b.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-5 Elements of the Prospective Analysis of the 1990 Clean Air Act Amendments Parameters Benefits evaluation points 2000 and 2010 Scenarios Evaluated conditions with and without implementation of Titles I-V of the 1990 Clean Air Act Amendments Pollutants modeled and methods used for air-quality modeling for benefits analysis Ozone – regional-scale version of the urban airshed model (UAM-V) for eastern and western United States; UAM-IV for Los Angeles, San Francisco, and Phoenix PM10 and PM2.5 – regional acid deposition model/regional particulate model for the eastern United States; regulatory modeling system for aerosols and acid deposition for the western United States CO, NOx, and SO2 – linear scaling procedure based on percent reduction in emissions Health outcomes quantified and monetizeda Ozone – chronic asthma; minor restricted-activity days and respiratory symptoms; hospital admissions (respiratory and cardiovascular illness); emergency room visits for asthma PM – premature mortality; bronchitis (chronic and acute); hospital admissions (respiratory and cardiovascular illness); emergency room visits for asthma; lower and upper respiratory symptoms; shortness of breath; minor restricted-activity days and respiratory symptoms; work-loss days CO – hospital admissions (respiratory and cardiovascular illness) NOx – hospital admissions (respiratory and cardiovascular illness); respiratory illness SO2 – hospital admissions (respiratory and cardiovascular illness); chest tightness, shortness of breath, or wheeze Concentration-response function used to estimate mortality benefits Pope et al. (1995) Threshold assumptions No thresholds above background concentrations assumed for modeled health outcomes

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations Parameters Lag-time assumptions 5-year lag structure assumed for PM-related premature deaths with 25% in years 1 and 2 and 16.7% in years 3, 4, and 5 Quantification of uncertainty 1. Calculated 5th and 95th percentiles that reflected within-study variance and across-study variability in both the health effects estimation and the economic valuation steps; 2. Provided alternative calculations for key assumptions; 3. Conducted sensitivity analyses Study populations evaluated for health outcomes Majority of benefits estimated for adult populations. PM mortality estimated for population 30 yr and older. Some hospital admissions studies use entire population; others use the population over 65 yr aMany other health outcomes were listed as unquantified for the listed pollutants. A few health outcomes were quantified but were not monetized because they were included in another benefits category. post-CAAA condition in which all rules stemming from passage of the 1990 CAAA are implemented. However, the post-CAAA condition does not include the recent regulations described in this chapter (PM and ozone NAAQS, Tier 2 emissions standards, and HD engine and diesel-fuel standards). EPA noted that the recent regulations use the prospective post-CAAA scenario as the baseline; therefore, the benefits estimates in those analyses are considered incremental to those estimated for the prospective analysis (EPA 1999b). Benefits are analyzed in the aggregate for Titles I-V, and annual estimates of benefits and costs are presented for the years 2000 and 2010. The present value of benefits and costs over the period 1990 to 2010 are also calculated. Categories of benefits estimated include health, visibility, agricultural, and ecological benefits. The process used to calculate the benefits is similar to that used to evaluate benefits for the Tier 2 and the HD engine and diesel-fuel rules. First, the changes in emissions of PM (PM2.5 and PM10), SO2, NOx, VOCs, and CO were estimated for the base-year 1990 and for the pre- and post-CAAA scenarios in 2000 and 2010. The changes in emissions are primarily associated with Titles I, II, and IV. The impacts of Title III on HAP emissions were not calculated; consequently, the health benefits

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations resulting from reductions in HAP emissions were also not calculated. Title V has no direct impact on emissions of the criteria air pollutants. The emissions estimates were then used to model or calculate changes in ambient air concentrations of ozone, PM, SO2, NOx, and CO. Ozone concentrations were modeled using UAM-V for the eastern and the western United States and UAM-IV for three metropolitan areas (Los Angeles, San Francisco, and Phoenix). Spatial resolution of the model was greater for the eastern United States (12- or 36-km square grids) than for the western United States (56-km square grids). Spatial resolution within the cities was still greater (4- or 5-km square grids). One or two simulation periods ranging from 2 to 10 days were used to generate hourly ozone concentrations. PM concentrations in the western United States were modeled using REMSAD, and PM concentrations in the eastern United States were modeled using the regional acid deposition model (RADM)/regional particulate model (RPM). Spatial resolution of the modeling was greater for the western United States (56-km grid squares) than for the eastern United States (80-km grid squares). Daily PM2.5 and PM10 concentrations were generated using “30 randomly selected 5-day periods spanning a four-year period” for the eastern United States and using one 10-day period for each season for the western United States. PM and ozone were modeled for the base-year 1990 and the pre- and post-CAAA scenarios in 2000 and 2010. Ambient concentrations used for the benefits analysis were calculated by adjusting the observed ambient pollutant concentrations in 1990 by a ratio of the predicted concentrations for 2000 or 2010 to the predicted concentrations for 1990. Data were interpolated for the nonmonitored sites in the country. Ambient concentrations of SO2, NOx, and CO were calculated using a linear scaling approach and the assumption that ambient concentrations are reduced by the same percent as the estimated emissions reductions. Accordingly, observed ambient concentrations were multiplied by the ratio of the predicted emissions for 2000 or 2010 to the emissions for 1990. Differences in ambient air concentrations, population estimates at given locations, and concentration-response functions for given health outcomes were used as inputs into CAPMS to generate benefits estimates for 2000 and 2010. The health benefits that were quantified and monetized in the study are summarized in Table 2-5 and included avoided cases of premature mortality and chronic bronchitis associated with PM, hospital admissions

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations associated with PM, ozone, CO, NOx, and SO2, and minor restricted-activity days associated with PM and ozone. Many other health outcomes were listed, but were not quantified (or were not included in the analysis) because of a lack of data or possibility of double-counting. Estimates of avoided cases of premature mortality were based on the Pope et al. (1995) study. No thresholds above background concentrations were assumed, and a 5-year lag structure was assumed for PM-related premature mortality (25% in the first and second years and 16.7% in each of the remaining 3 years). Uncertainties in the analysis were addressed by quantitative estimates, qualitative discussions, alternative calculations for key assumptions, and sensitivity analyses. EPA calculated 5th and 95th percentiles that reflected within-study variance and across-study variability in both the health effects estimation and the economic valuation steps. The statistical estimates did not reflect uncertainty in other phases of the analysis (emissions and air-quality modeling). Each stage of the analysis included qualitative discussions about the bias and significance of key uncertainties for that stage of the analysis. Alternative calculations were presented for a few key assumptions. For example, the Dockery et al. (1993) study was used to estimate avoided cases of premature mortality rather than the Pope et al. (1995) study, and a VSLY approach was used to value the premature mortality rather than the VSL approach, which was used for the primary estimate. Several sensitivity analyses were conducted, including one intended to evaluate the influence of the largest source of uncertainty. The annual mean health benefits for the prospective analysis of the 1990 CAAA are summarized in Table 2-6 for 2010. The monetized values of the health benefits are also provided. As in the other analyses evaluated, the mortality benefits dominate the monetized benefits. REFERENCES Dockery, D.W., C.A. Pope, X. Xu, J.D. Spengler, J.H. Ware, M.E. Fay, B.G. Ferris, and F.E. Speizer. 1993. An association between air pollution and mortality in six U.S. cities. N. Engl. J. Med. 329(24):1753-1759. EPA (U.S. Environmental Protection Agency). 1997. Regulatory Impact Analyses for the Particulate Matter and Ozone. National Ambient Air Quality Standards (NAAQS) and Proposed Regional Haze Rule. Regulatory Economic Analysis Inventory. A.97.9. Office of Air Quality Planning and Standards, Office of Air and Radiation, U.S. Environmental Protection Agency, Research Triangle Park, NC.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations TABLE 2-6 Annual Mean Health Benefits (Avoided Cases of Morbidity and Mortality and Monetized Values) for the Prospective Analysis of the 1990 CAAA for 2010 Health Outcome Pollutant Avoided Casesa Monetized Value (1990$ in millions) Mortality (ages 30 and older) PM 23,000 (14,000-32,000) 100,000 Chronic bronchitis PM 20,000 (5,000-34,000) 5,600 Chronic asthma Ozone 7,200 (1,800-12,000) 180 Hospitalization   All respiratory illness PM, CO, NO2, SO2, Ozone 22,000 (13,000-34,000) 130 Total cardiovascular illness PM, CO, NO2, SO2, Ozone 42,000 (10,000-100,000) 390 Emergency room visits for asthma PM, Ozone 4,800 (430-14,000) 1 Acute bronchitis PM 47,000 (0-94,000) 2 Upper respiratory symptoms PM 950,000 (280,000-1,600,000) 19 Lower respiratory symptoms PM 520,000 (240,000-770,000) 6 Respiratory illness NO2 330,000 (76,000-550,000) 6 Moderate or worse asthmab PM 400,000 (80,000-720,000) 13 Asthma attacksb Ozone, PM 1,700,000 (920,000-2,500,000) 55 Chest tightness, shortness of breath, or wheeze SO2 110,000 (290-520,000) 0.6 Shortness of breath PM 91,000 (26,000-150,000) 0.5 Work-loss days PM 4,100,000 (3,600,000-4,600,000) 340 Minor restricted-activity days and any of 19 respiratory symptoms Ozone, PM 31,000,000 (25,000,000-37,000,000) 1,200 aMean value provided with 5th and 95th percentile values shown in parentheses. bThese results were not included in the total benefits estimate because they overlap with health outcomes included in the category for minor restricted-activity days and any of 19 respiratory symptoms. Source: Adapted from EPA 1999b.

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Estimating the Public Health Benefits of Proposed Air Pollution Regulations EPA (U.S. Environmental Protection Agency). 1999a. Regulatory Impact Analysis—Control of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements. EPA 420-R-99-023. Engine Program and Compliance Division, Office of Mobile Sources, Office of Air and Radiation, U.S. Environmental Protection Agency. December 1999. [Online]. Available: http://www.epa.gov/OMS/regs/ld-hwy/tier-2/frm/ria/r99023.pdf [accessed September 10, 2002]. EPA (U.S. Environmental Protection Agency). 1999b. Final Report to Congress on Benefits and Costs of the Clean Air Act, 1990 to 2010. EPA 410-R-99-001. Office of Air and Radiation, U.S. Environmental Protection Agency. November 1999. EPA (U.S. Environmental Protection Agency). 1999c. Final Tier 2 Rule: Air Quality Estimation, Selected Health and Welfare Benefits Methods, and Benefits Analysis Results. EPA 420-R-99-032. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. December 1999 . [Online]. Available: http://www.epa.gov/otaq/regs/ld-hwy/tier-2/frm/tsd/r99032.pdf [accessed September 10, 2002]. EPA (U.S. Environmental Protection Agency). 2000a. Regulatory Impact Analysis: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements. EPA 420-R-00-026. Office of Air and Radiation, U.S. Environmental Protection Agency, Washington, DC. December 2000. EPA (U.S. Environmental Protection Agency). 2000b. Final Heavy Duty Engine/Diesel Fuel Rule: Air Quality Estimation, Selected Health and Welfare Benefits Methods, and Benefit Analysis Results. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. December 2000. [Online]. Available: http://www.epa.gov/ttnecas1/regdata/tsdhddv8.pdf [accessed September 10, 2002]. Krewski,D., R.T.Burnett, M.S.Goldberg, K.Hoover, J.Siemiatycki, M.Jerrett, M. Abrahamowicz, and W.H. White. 2000. Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of Particulate Air Pollution and Mortality, A Special Report of the Institute's Particle Epidemiology Reanalysis Project. Final Version. Health Effects Institute, Cambridge, MA. July 2000. [Online]. Available: http://www.healtheffects.org/pubs-special.htm [accessed September 10, 2002]. Pope, C.A. III, M.J. Thun, M.M. Namboodiri, D.W. Dockery, J.S. Evans, F.E. Speizer, and C.W. Heath. 1995. Particulate air pollution as a predictor of mortality in a prospective study of U.S. adults. Am. J. Respir. Crit. Care Med. 151(3 Pt 1): 669-674.