ENVIRONMENTAL POLICY ANALYSIS
AIR QUALITY
UV-B Screening by Tropospheric Ozone: Implications for the National Ambient Air Quality Standard RANDALL LUTTER, CHRISTOPHER WOLZ U.S. Office of Management and Budget Washington, DC 20503
Tropospheric ozone reduces human exposure to harmful ultraviolet-B (UV-B) radiation. A 10-ppb decrease in seasonal average concentrations of ozone (about 20%) is estimated to lead to increases in cancers and cataracts valued at $0.29 billion to $1.1 billion annually. EPA in its ongoing review of the National Ambient Air Quality Standard for ozone should set a standard to minimize all identifiable health effects, including UV-B radiation-related effects. If these estimates are confirmed, this approach may reduce avoidable cancers, cataracts, and deaths by leading to a different standard than that recently proposed in a program already costing more than $20 billion annually.
1 4 2 A • VOL. 3 1 , NO. 3, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
Tropospheric ozone, which has well-known adverse effects on the human respiratory system, reduces human exposure to damaging ultraviolet-B (UV-B) radiation in a manner similar to ozone (03) in the stratosphere. Although this effect is well recognized (2), EPA has not formally considered it in developing its recent proposal (2) to tighten the National Ambient Air Quality Standard (NAAQS) for tropospheric 03—a standard that underlies EPA's flagship air pollution control program. Under the Clean Air Act, EPA is mandated to set the health-based "primary" NAAQS to protect public health with an adequate margin of safety, based on an assessment of all identifiable healdi effects (3). The current standard-setting effort has focused exclusively on protection from the adverse respiratory effects of 0 3 . Consideration of the UV-B screening effect by tropospheric 0 3 may lead to a form and level of the standard quite different from what would otherwise be set. Our preliminary analysis suggests that the value of increased UV-B-related health effects from tropospheric 0 3 reductions may be similar in magnitude to the value of decreased respiratory health effects In addition we find the exposure periods of con~ for respiratory effects Eire generally no more ttitin 8 h (the averaging time for EPA's proposed revised NAAQS) and are decades for most UV-B effects Consideration of all the effects of tropospheric O mav be necessary in setting regulatory standards that ensure the fullest protection of public health Ozone chemistry and federal standards Ozone is a naturally occurring reactive gas present in the troposphere (up to 10 km altitude) and in the stratosphere. In the troposphere, 0 3 occurs through downward transport from the stratosphere or by photochemical production involving solar radiation, volatile organic compounds (both anthropogenic and biogenic), and nitrogen oxides (largely anthropogenic) (4). Ozone varies significantly by season, latitude, time of day, and weather conditions. Average July daily high hourly concentrations for tropospheric 0 3 are 60-65 ppb in polluted areas and 50 ppb in areas that attain the current stcindcird; lows tire less man 20 ppb (5). Peak hourly urban concentrations often Tcirifife from 70 to 160 ppb (6), although because of ozone's large diurnal variations these concentrations do not necessarily imply levels in excess of EPA's proposed 80-ppb standard for an 8-h average concentration Ozone throughout the atmosphere absorbs UV-B radiation, thereby reducing risks of UV-B-induced skin cancers and cataracts (2, 7). Increases in such risks have become a concern since 1974, when chlorofluorocarbons (CFCs) and other manufactured chemicals were identified as likely to deplete stratospheric 0 3 (8). Stratospheric 0 3 loss attributed largely 0013-936X/97/0931-142AS14.00/0 © 1997 American Chemical Society
to emissions of synthetic ozone-depleting substances has been measured (9), and increases in UV-B radiation at ground level have been reported {10). EPA regulates and bans ozone-depleting chemicals at a total annual cost to the United States of more than $1.2 billion (1994 dollars) (11, 12). Tropospheric 0 3 , as well as cloud cover and aerosols such as sulfate particles, has been widely recognized as playing a role in attenuating UV-B radiation (1, 9,13-17). This screening effect is, however, independent of any depletion of stratospheric 0 3 and exists in its absence. The only consideration of stratospheric 0 3 relevant in assessing tropospheric 0 3 health impacts is the generally quite small effect of stratospheric 0-. depletion on the magnitude of UV-B screening by tropospheric 0 3 .
The ozone NAAQS The Clean Air Act directs EPA to set primary ambient air quality standards for certain pollutants, "the attainment and maintenance of which in the judgement of the Administrator, based on such criteria and allowing an adequate margin of safety, are requisite to protect the public health (3)." The act also directs EPA to establish a secondary standard "to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air." Ozone in the troposphere has been a regulatory priority of EPA because of the effect of 0 3 on human respiratory function. EPA established the current 0 3 primary NAAQS in 1979 at 120 ppb, measured as a daily maximum hourly average, not to be exceeded more than three times over three successive years (18). EPA set that level on the basis of identified effects of O. on lung function and symptoms from short-term acute exposures (1 to 3 h) at levels above 120 ppb and in consideration of effects on sensitive subpopulations. The effects of exposures to 0 concentrations of 80 ppb over 6 to 8 h on adults exercising at moderate and heavy levels include discomfort coughing some loss of lung function increased airwav responsiveness and inflammation In healthy adults these effects are generally transient and fully reversible within 24 h Human health effects from chronic exposure to elevated levels of 0 have not been documented although permanent structural damapp to lung tissue has bppn identifiprl in animals siihiprt to chronic eynosurp leading to concern about possible links to chronic bronchitis and emphysema in humans (19) About 110 million U.S. residents live in "nonattainment" areas that fail to meet the current 0 3 NAAQS (20). In its program to meet the NAAQS, EPA regulates emissions of 0 3 precursors from a broad range of sources such as motor vehicles, fuels, power
plants, and printing operations. Estimates of the current cost of controls to reduce 0 3 exceed $20 billion— yet these controls are not sufficient to attain the standard in all areas (21, 22).
EPA's review of the NAAQS EPA has proposed a new 0 3 standard that would require that the three-year average of the third highest daily maximum 8-h reading for a year not exceed 80 ppb. EPA has committed to making its final decision by June 1997 (2). EPA's proposal states that a revised standard is called for to protect against the health effects of exposures of up to 8 h and to provide increased protection for sensitive subpopulations. EPA's analysis indicates that such a revised standard could increase the size and number of "nonattainment" areas to include approximately 30 million additional people (23). In its proposal EPA also asked for public comment on the adoption of a separate secondary standard based on a measure of daytime O- over three months. An important part of EPA's decision-making record for this NAAQS review is the "Criteria Document" (CD) called for in the Clean Air Act to "accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health or welfare which may be expected from the presence of such pollutant in the ambient air, in varying quantities" (24). EPA's June 1996 "Staff Paper," based on this CD, concluded that the current NAAQS does not provide adequate public health protection and recommended adoption of an 8-h average 0 3 NAAQS, between 70 and 90 ppb, not to be exceeded more than one to five times per year on average over three successive years (25). EPA's Clean Air Scientific Advisory Committee (CASAC) reviewed the CD and Staff Paper and endorsed EPA staff recommendations for an 8-h, 70- to 90-ppb primary standard (26). CASAC also endorsed EPA staff recommendations for a distinct secondary standard based on daytime concentrations over three months to protect public welfare from known or anticipated adverse effects EPA's published proposal the CD and the Staff Paper do not discuss the health effects or welfare-related effects of UV-B screening by tropospheric O
Health effects of tropospheric ozone UV-B screening by tropospheric 0 3 is generally acknowledged by researchers investigating the effects of stratospheric 0 3 depletion on UV-B (1,10) and has been identified by direct measurement. For example, in Los Angeles during the 1980s, UV-B absorption by 0 3 , as well as N 0 2 and S0 2 , was estimated to have reduced erythemal irradiance for July by 6-8% of the value for "clean skies" (27). In Chicago in July unVOL. 31, NO. 3, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 1 4 3 A
Health effects of a decline in tropospheric ozone The U.S. Department of Energy's Office of Health and Environmental Research has estimated that a 10-ppb reduction in seasonal average tropospheric ozone would increase the number of deaths caused by skin cancers and raise the number of cataract cases yearly (29). Nonmelanoma skin cancers, total cases: 2000-11,000 Melanoma skin cancers Total cases: 130-160 Fatalities: 25-50 Cataracts, total: 13,000-28,000
der "clear skies," a 10-ppb decline in 0 3 was associated with a 1.3±1.2% increase in (erythemal) UV-B {16). On the basis of a preliminary estimate by EPA that a 10-ppb reduction in seasonal average tropospheric 0 3 (below 2 km altitude) would yield a reduction to total column 0 3 of 1.6 Dobson units, or about 0.5% (28), Department of Energy (DOE) staff developed estimates of the health effects that would result from such a change. These include 25-50 annual deaths caused by melanoma skin cancers, and 13,000-28,000 cataracts per year (29) (see box). In an apparent response to these estimates, EPA stated in the regulatory impact analysis (RIA) in support of its proposal that it has conducted an analysis and review of the extent to which the kinds of O reductions anticipated for the difference between the current 1-h and possible [8-h] standards might produce UV-B-related health effects. According to EPA's RIA "[t]he review concluded '(1) the numbers resulting from these calculations are quite small and (2) the limitations of the accuracy and reliability of the input to the calculations produce numbers that cannot be defended whether large or small' " (30) DOE also noted the likelihood of "UV-B enhanced immunosuppressive effects that activate latent viruses or increase incidence and/ or severity of some infectious diseases" (29, 31). DOE recommended that EPA give "consideration to both the beneficial health effects of reducing tropospheric 0 3 concentrations and the potentially harmful effects that these reductions will have due to increased penetration of UV-B." Estimates similar to DOE's are straightforward to derive using published methods. United Nations Environment Programme (UNEP) analysis (1) implies that a 10-ppb reduction in average July 0 3 levels at a latitude of 40° north (e.g., Philadelphia) and with a constant 0 3 mixing ratio to 10 km altitude would lead to increases in DNA-weighted dose of about 4% in July and 3% in January. (Such a dose weighs increases in UV of different wavelengths by effects on DNA.) This UNEP estimate is equivalent to an increase of 2.5% in erythemal UV-B dose, given a radiation amplification factor for erythemalweighted dose of 1.2 and for DNA-weigh ted dose of 1.9 (1). This figure is roughly twice the comparable estimate in Frederick et al. (16) which is for clear skies and a higher latitude It is also larger than the 0 6% increase in erythemal UV-B dose that would result from the 0 5% decrease in total column O underlying DOE's analysis We estimate that the nonmelanoma skin can1 4 4 A • VOL. 31, NO. 3, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
cers (NMSC) resulting from a 10-ppb decline in tropospheric 0 3 , given the alternative estimated increases of 1.3% and 2.5% in erythemal-weighted UV-B dose, would range from 4200 to 8100 cases per year. We use biological amplification factors (BAFs) for squamous and basal skin cancer of 2.5±.7 and 1.4±.4, and a baseline of 100,000 squamous and 500,000 basal cell carcinomas annually in the United States (32), assumed to occur in 0 3 nonattainment areas in proportion to population. We assume, based on Frederick and Weatherhead (27), that 80% of UV-B exposure occurs in the warmer months when the 10ppb reduction would result. Using lower bound BAFs and the UV-B dose increase from Frederick et al. (16) would yield 3000 NMSC cases per year; the upper bound BAFs and the UV-B dose increase from UNEP (1) would give about 10 000 cases. Mortality incidence from NMSCs is about 0.3% (33), implying an increase of 9-30 deaths from NMSC per year. This estimate would range from 37 to 130 per year using the range of 3000-10,000 NMSCs and mortality assumptions previously used by EPA (34). The true uncertainty in these estimates is much larger than the range presented here. For example, the lower bound of the 95% confidence interval in Frederick et al. (16) is about 8% of their best estimate. This uncertainty should be evaluated formally and compared, for example, with the uncertainty in the estimated risk of 03-related respiratory effects. These preliminary estimates illustrate the risk assessment method and show that the UV-B-related health effects are sufficiently well documented and large to merit consideration in setting the NAAQS. Quantitative estimates of other health effects such as cataracts are not developed here but are possible using existing methods (1, 34). These preliminary estimates are not definitive but may help corroborate DOE's estimates of NMSCs. These estimated UV-B-related health effects are relevant only if current and foreseeable emission controls adopted to attain a revised 0 3 NAAQS are expected to lead to reductions in the range of 10 ppb. No direct measures of changes in seasonal average 0 3 levels resulting from emission controls exist. EPA estimated, however, that in one district in Philadelphia summer 0 3 concentrations (90th percentile) would have to fall from 72 ppb to 54 ppb to attain an 80-ppb, 8-h, one expected violation of the standard (slightly more stringent than the proposed revised standard) (35). Further, 0 3 reductions in this range have been observed for some areas that, despite still fail to meet the current NAAQS. In Chicago an annual decline of 0.5% in daily maximum 1-h O concentrations was estimated between 1981 and 1991 (36); in Los Angeles a decline over a decade in 24-h average O of 4 6± 3 ppb was measured (27); and measurements in California nonattainment areas show declines of more than 5 DDb throughout the sunniest hours of the day from 1982 to 1987 (5) Implications for NAAQS The existence of identifiable adverse human health effects that increase as tropospheric 0 3 levels decrease raises questions about how to set the NAAQS under the Clean Air Act. A primary standard that rec-
ognizes the tradeoff between the adverse respiratory effects and the reductions in UV-B-related health risks may correspond best with the act's requirement that the primary standard be set to "protect the public health." Similarly, a secondary standard set in consideration of all effects, including, for example, detrimental effects of UV-B on crop yields— analyzed by EPA for other programs {34)—may better match the statutory directive to protect "public welfare." Similar risk-risk tradeoffs in other contexts have previously been noted and incorporated in standard-setting efforts {37). Recognition of this tradeoff for the primary NAAQS would require EPA to develop estimates of the incidence of various health effects. The calculation of incidence is feasible but complex because of the variability in individual sensitivity to 0 3 and UV-B and because of the variability in exposure, which depends on atmospheric conditions and individual behavior. Even with incidence estimates in hand, the question of how to set the NAAQS remains. If such estimates could be aggregated, however, EPA could identify a standard that would minimize all identifiable health effects of tropospheric 0 3 . One way to aggregate would be to use qualityadjusted life-years (38), an approach common in the medical community but rare in regulatory decision making. EPA commonly uses an alternative aggregation methodology based on estimates of willingness to pay for reductions in mortality and morbidity risks (and non-health risks). Valuing changes in health risks in dollar terms is an analysis endorsed by guidance from the Office of Management and Budget {39). Indeed, EPA has analyzed the costs and benefits of the recent proposed NAAQS revision {30) so as to comply with Executive Order No. 12866 on Regulatory Planning and Review {40), even though the Clean Air Act does not allow consideration of costs by EPA in decisions to set the health-based primary NAAQS. An example of a health benefit valuation prepared by EPA in 1992, the stratospheric 0 3 program phase-out of CFCs {11), included the valuation of the average costs of NMSCs at about $4000 for a basal cell carcinoma case and $7000 for a case of squamous cell carcinoma. The average cost for a case of cutaneous malignant melanoma was estimated to be $15,000. EPA estimated social willingness to pay to avoid cataracts at $15,000. The value of reduced risk of mortality was estimated to be between $3 million and $12 million per statistical life, somewhat above other recommended ranges {41). Using these EPA unit values we calculate the annual value of adverse health effects presented earlier as between $0.29 billion and $1.1 billion per year (see box, "Valuation of annual UV-B-related health effects"). This estimate understates total value by excluding unquantified effects and by using avoided medical costs rather than the willingness to pay. This valuation also ignores delays in changes in risk relative to changes in exposure; such delays imply that these effects should be discounted. EPA has estimated the economic value of respiratory health improvements that would result if air quality improved from attainment of the current stan-
Valuation of annual UV-B—related health effects By combining the Department of Energy's projections of health effects (previous box) with prior EPA estimates of the cost of these health effects {11), the following calculations of the potential increased health costs of a 10-ppb decline in tropospheric ozone were made (in millions of 1994 dollars). Skin cancers Nonmelanoma cases: $10-52 Melanomas Cases: $2.0-2.5 Fatalities: $79-630 Cataracts: $210-440 Total: $290-1100
dard to attainment of alternative standards that are similar to EPA's recent proposal {30). For example, an 8-h standard of 80 ppb with 4 annual violations of the standard would provide annual benefits of between $5 million and $1.44 billion, with a "best" estimate—depending on the estimation method—of $12 million or $32 million per year (figures adjusted to 1994 dollars). Of the upper bound benefits estimate, $1.42 billion per year is attributable to an association with daily deaths observed by Moolgavkar et al. {42) in Philadelphia, but not, for example, in Los Angeles, which has significantly higher 0 3 concentrations {43). Attainment of the proposed standard would give slightly larger benefits. These preliminary data suggest that the UV-Brelated adverse health effects of reducing tropospheric 0 3 to comply with the current 0 3 NAAQS or to attain EPA's proposed more stringent NAAQS may be similar in magnitude to the respiratory-related beneficial health effects of such an 0 3 reduction. These estimated values are not entirely comparable, because the value of the UV-B-related effects is for a 10-ppb decline in seasonal average 0 3 , whereas EPA's estimated benefits are for improvements in 0 3 from attainment of the current standard to attainment of a new standard as recently proposed. Nonetheless, a "health-optimal" O NAAQS might differ significantly from a NAAQS set without consideration of UV-B-related deaths and disease and it could even be less stringent than the current O NAAQS Many of the beneficial effects of UV-B screening by tropospheric 0 3 appear to be related to longterm exposures, whereas the identified adverse respiratory effects are related primarily to exposures to peak 0 3 levels over 6-8 h or less {1,19). (Some melanoma skin cancers and relatively poorly understood long-term lung damage provide the key exceptions.) Thus a standard that minimizes all health effects of 0 3 could lead to the establishment of a short-term peak maximum concentration (i.e., 1 or 8 h) and a seasonal average minimum concentration. Attainment of such a standard may require control strategies that lower peak concentrations of 0 without lowering seasonal averages. Such "peak reducing" strategies may protect public health better than annual or seasonal strategies to control O EPA's ability under the Clean Air Act to such peakreducing control strategies is uncertain (441 UV-B-related cancers and cataracts associated VOL. 31, NO. 3, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 1 4 5 A
with foreseeable reductions in tropospheric 0 3 are sufficiently understood to be considered in setting the 0 3 NAAQS. In its ongoing revision of the 0 : ! NAAQS, EPA could set a primary standard that would minimize the aggregate health effects of tropospheric 0 3 , including identifiable protective effects on UV-B-related cancers and cataracts. Such an approach would be consistent with the Clean Air Act's requirement to protect the public health. Such a health-optimal standard would represent a challenging departure from current practice but is feasible given current analytic techniques. This change to the standard setting may be necessary to reduce avoidable cancers, cataracts, and deaths. In setting a secondary welfare-based standard EPA could also consider UV-B-related effects on crops Other regulated pollutants, such as NOx> S0 2 , and particulate matter [also the subject of a recent NAAQS proposal (45)] have been noted as screening UV-B (i, 15), and the quantification of these UV-Brelated health effects should be pursued in current standard-setting efforts.
Acknowledgments T h a n k s to Rick Belzer, l o h n Frederick, a n d a n o n y m o u s reviewers. Special t h a n k s goes to Art Fraas for helpful s u p p o r t . T h e a u t h o r s are with t h e U.S. Office of M a n a g e m e n t a n d Budget. T h e views e x p r e s s e d in this p a p e r are entirely t h e i r o w n a n d n o t n e c e s s a r i l y t h o s e of a n y g o v e r n m e n t agency. (Received for review F e b r u a r y 15, 1996. Revised m a n u s c r i p t received N o v e m b e r 19, 1996. Accepted N o v e m b e r 20, 1996.)
References (1)
(2) (3) (4)
(5) (6)
(7) (8) (9)
(10) (11)
(12) (13)
(14) (15) (16) (17) (18) (19)
Environmental Effects of Ozone Depletion: 1994 Assessmen,, United Nations Environment Programme: Nairobi, Kenya, 1994. Fed. Regis.. 1996, 61, 65716. "CleanAir Act"; Public Law 101-549,1970; 42 United States Code 7409. National Research Council. Rethinking the Ozone Problem in Urban and Regional Air Pollution; National Research Council: Washington, DC, 1991. Henderson, J. V. American Economcc Review 1996, 86(4), 789. "National Air Quality and Emissions Trends Report 1993"; Office of Air a n d Radiation. Office of Air Quality Planning and Standards, Technical Support Division. U.S. Environmental Protection Agency: Research Triangle Park, NC, October 1994; No. 454/R-94-026. Setlow, R. B. Proc. Nat. Acad. Sci. USA 1974, 71 (9), 3363. Molina, M. I.; Rowland, F. S. Natuee 1974, 249, 810. Scientific Assessment of Ozone Depleiion: 1994; World Meteorological Organization, Global Ozone Research and Monitoring Project: Geneva, Switzerland, 1995; Report No. 37. Herman, J. R. et al. Geophys. Res. Lett. 1996, 23(16), 2117. Regulatory Impatt Analysis: Compliance with Section 604 of the Clean Air Act for the Phaseout of Ozone Depleting Chemicals. Prepared by ICF Incorporated for U.S. Envir o n m e n t a l Protection Agency, Office of Air and Radiation, Global C h a n g e Division: Washington, DC, 1992. Fed. Regist. 1993, 58, 65018. "Environmental Effects of Ozone Depletion: 1991 Update, Panel Report"; United Nations E n v i r o n m e n t Prog r a m m e : Nairobi, Kenya, November 1991. Liu, S. C ; McKeen, J. A.; Madronich, S. Geophys. Res. Lett. 1991, 12, 2265. Seckmeyer, C ; McKenzie, R. L. Natuee 1992, 359, 135. Frederick, I. E. et al. /. App.. Meteorology, 1993, 32, 1883. Bruhl, C ; Crutzen, P. J. Geophys. Res. Lett. 1989, 16(7), 703. Code Fed. Reg. 40, 50.9(a). Air Quality Criteria for Ozone and Related Photochemical Oxidants; Office of Health and E n v i r o n m e n t a l Assessment. Environmental Criteria a n d Assessment Office. U.S. E n v i r o n m e n t a l Protection Agency: Research Triangle Park, NC, 1996; EPA/600/P-93/004aF-cF.
1 4 6 A • VOL. 31, NO. 3. 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
(20) MEMORANDUM: Distribution of Updated Condensed Nonattainment List, July 29,1996 (press release); Air Quality Trends Analysis Group, Office of Air Quality Plann i n g a n d S t a n d a r d s . U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency: Research Triangle Park, NC, 1996. (21) Hahn, R. Nationll Resources Journal 1994, 34(1), 312. (22) Catching Our Breath: Next Steps for Reducing Urban Ozone, July 1989. U.S. Congress, Office of Technology Assessment: Washington, DC, 1989; OTA-O-412. (23) Air Quality Maps for Alternative Standards and Supporting Materials, Aprll 25, 1994. O z o n e / C a r b o n Monoxide Programs Branch, Air Quality M a n a g e m e n t Division, Office of Air Quality Planning a n d Standards. U.S. Environmental Protection Agency: Research Triangle Park, NC, 1994. (24) "Clean Air Act"; Public Law 101-549, 1970; 42 United States Code 7408. (25) Review of National Ambient Air Quality Standards for Ozone, Assessment of Scientific and Technical Information, OAQPS Staff Paper. Office of Air Quality Planning a n d Standards. U.S. Environmental Protection Agency: Research Triangle Park, NC, 1996; EPA-452/R-96-007. (26) Wolff, G. T. Letter(s) to H o n o r a b l e Carol Browner, Administrator, U.S. Environmental Protection Agency; EPASAB-CASAC-LTR-96-(002, 006). Appendix G of EPA-452/ R-96-007. (27) Frederick, J.; Weatherhead, E. "Regional Variations in Surface Ultraviolet Irradiance: An Analysis Based o n Gaseous Air Pollutants"; final report to the Alternative Fluo r o c a r b o n s Environmental Acceptability Study on Contract CTR90-12/P90-031; D e p a r t m e n t of the Geophysical Sciences, The University of Chicago; Chicago, IL, 1992. (28) Impatt of Changes in Tropospheric Ozone on UV-B Flux: Preliminary Calculations by EPA Staff, Novembrr 15,1994. Submitted with DOE remarks at March 21, 1995, Public Meeting of Clean Air Scientific Advisory Committee, Review of Criteria D o c u m e n t for Ozone and Related P h o tochemical Oxidants, Chapel Hill, NC; U.S. Environmental P r o t e c t i o n Agency Science Advisory Board Public M e e t i n g File; W a s h i n g t o n DC 1995; ECAO-CD-920746 (29) U.S. D e p a r t m e n t of Energy, Office of Health and Envir o n m e n t a l Research; remarks p r e s e n t e d at March 21, 1995, Public Meeting of Clean Air Scientific Advisory Committee; U.S. Environmental Protection Agency Science Advisory Board Public Meeting File; Washington, DC, 1995; ECAO-CD-92-0746. (30) Regulatory Impatt Analysis for Proposed Ozone National Ambient Air Quality Standard, Ch. IV; U.S. Environmental Protection Agency: Research Triangle Park, NC, Dec. 1996. (31) Science 1992, 257, 1211. (32) Grant-Kels, J. Pediatric Dermatology 1993, 10, 1. (33) Wingo, R A. et al. Ca Cancer J. Clin. 1995, 45, 8. (34) Regulatory Impatt Analysis: Protection of Stratospheric Ozone Volume I, Ch. 2; Office of Air a n d Radiation. U.S. Environmental Protection Agency: Washington, DC, Dec. 1987. (35) Johnson, T. et al. "Estimation of Ozone Exposures Experienced by O u t d o o r Workers in Nine U r b a n Areas Using a Probabilistic Version of NEM," C o n t r a c t No. 63-D30094; p r e p a r e d for U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency, Office of Air Quality Planning and Standards; Research Triangle Park, NC, 1996. (36) Cox, W ; Chu, S. Atmo.. Environ. 1993, 278(4), 425. (37) Graham, J.; Weiner, J. Risks versus Risks, Tradeoffs in Protecting Heatth and the Environment; Harvard University Press: Cambridge, MA, 1995. (38) Tolley, G.; Kenkel, D.; Fabian, R. Valuing Health for Policy: An Economcc Approach; University of Chicago Press: Chicago, IL, 1994. (39) Economcc Analysis of Federal Regulations Under Executive Order 12866; U.S. Office of M a n a g e m e n t a n d Budget: W a s h i n g t o n , DC, J a n u a r y 1996. At: h t t p : / / w w w . whitehouse.gov/WH/EOP/OMB/html/miscdoc. (40) Fed. Regist. 58, 51735, Oct. 4, 1993. (41) Viscusi, W. K. Journal of Economcc Literature 1993, 31 (4), 1912. (42) Moolgavkar, S. et al. Epidemiol. 1995, 6(5), 476. (43) Kinney, P. L.; Ozkaynak, J. Environ. Res. 1991, 54, 99. (44) "Clean Air Act"; Public Law 101-549, 1970; 42 United States Code 7602. (45) Fed. Regis.. 1996, 61, 65638.
