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On December 8, 2009, the United Stat es Environmental Protection Agency (“EPA” or the “Agency”) proposed revisions to its primary National Ambient Air Quality Standards (“NAAQS”) for sulfur dioxide (“SO 2 ”). 74 Fed. Reg. 64810 (Dec. 8, 2009) (“Proposed Rule”). Specifically, the Agency proposed to adopt a new SO 2 NAAQS to limit the annual 99 th percentile daily maximum hourly SO 2 concentration, averaged over three years, to a level within the range of 50 to 100 parts per billion (“ppb”) and to revoke the present annual arit hmetic average standard of 0. 03 parts per million (“ppm”) (30 ppb) and 24-hour average standard of 0. 14 ppm (140 ppb) that may not be exceeded more than once a year. Id. at 64810/1. EPA also sought comment on the alternative of a daily maximum 1-hour SO 2 standard as high as 150 ppb. Id. at 64845/1. Finally, the Agency addressed various pr ovisions for implementing any new SO 2 NAAQS. Id. at 64846/1 - 64864/3. These are the comments of the Utility Air Regulator y Group (“UARG”) on the Proposed Rule. 1 UARG has participated actively th roughout the current review of the SO 2 NAAQS, submitting comments to EPA and to its Clean Air Scientific Advisory Committee (“CASAC” of the “C ommittee”) on drafts of the Integrated Science

1 UARG is a voluntary, nonprofit group of individual electric generating utilities and industry trade associations. UARG’s pu rpose is to participate on behalf of its members collectively in EPA’s rulemaking and other Clean Air Act proceedings that affect the interests of electr ic generators, and in related litigation. Since 1977, UARG has participated in virtually all key rulemaki ngs, related litigati on, and other arenas of policy development under the Clean Air Act t hat affect electric utility companies.2 Assessment (“ISA”), 2 and of the Risk and Expos ure Assessment (“REA”) 3 on which the Administrator relies in the Proposed Rule. 4 Those comments, which are hereby incorporated by reference in these comm ents on the Proposed Rule itself, address in

2 EPA, Integrated Science Assessment for Sulfur Oxides -- Health Criteria (September 2008).

3 EPA, Risk and Exposure Assessment to Support the Review of the SO 2 Primary National Ambient Air Qualit y Standards: Final Report (July 2009).

4 See Comments of the Utility Air Regula tory Group on the Risk and Exposure Assessment to Support the Review of the SO 2 Primary National Ambient Air Quality Standards: Second Draft (March 2009) (Docket ID. No. EPA-HQ-OAR-2007-0352- 0031.1) (June 11, 2009) (“Second Draft REA Co mments”); Anne E. Smith, Ph.D., Comments to CASAC on Draft #2 of the SO 2 Risk And Exposure Assessment, Public Comments Session, CASAC M eeting (Apr. 16-17, 2009) (Comments prepared on behalf of UARG), available at http://yosemite.epa.gov/sab/SABPRODUCT. NSF/PeopleSearch/F99F04D90A9425BE8 52575450067337C?OpenDocument; Comments of t he Utility Air Regulatory Group on the First External Review Draft of the Risk and Exposure Assessm ent to Support the Review of the SO 2 Primary National Ambient Air Q uality Standards: Second Draft (July 2008) (Docket ID No. EPA-HQ-OAR-2007- 0352-0014.1) (Aug. 28, 2008, corrected Sept. 4, 2008) (“First Dra ft REA Comments”); Comments of the Utility Air Regulatory Group on the Second External Re view Draft of the Integrat ed Science Assessment for Sulfur Oxides -- Health Criteria (M ay 2008) (Docket ID No. EPA-HQ-ORD-2006-0260- 0020.1) (Aug. 11, 2008) (“Second Draft ISA Comments”); Ti mothy H. Savage, Ph.D., Comments on Risk and Exposure Assessment to Support the Review of the SO 2 Primary National Ambient Air Quality Standards: First Dra ft (Presentation on behalf of UARG to CASAC meeting of Dec. 5-6, 2007) ; J. Turim, Ph.D., S. Moolgavkar, M.D., Ph.D., E. Anderson, Ph.D., A.T.S.F. , Comments on EPA’s Integrated Science Assessment for Sulfur Oxides -- Health Cr iteria: Summary (Dec. 3, 2007) (written presentation to CASAC meeting of Dec. 5-6, 2007); Comments of the Utility Air Regulatory Group on the First External Re view Draft of the Integrated Science Assessment for Sulfur Oxides -- Health Cr iteria (Sept. 2007) (D ocket ID No. EPA-HQORD-2006-0260-0009.1) (Nov. 30, 2007) (“First Dr aft ISA Comments”). Statements to CASAC do not appear to have been added to the public docket, although EPA states that the Administrator cons idered them in developing her rationale for the Proposed Rule. 74 Fed. Reg. at 64814/2. Copies of the presentations to CASAC by Timothy H. Savage, Ph.D. and by J. Turim, Ph.D., et al . are attached hereto as Attachments A and B respectively.3 detail EPA’s assessment of the science concerning SO 2 health effects and the risk of such health effects in contem porary ambient American air. For the reasons explained below and in those earlier comments, UARG does not support the proposed 1-hour NAAQS in the r ange of 50 to 100 ppb, or even one at the alternative 150 ppb level. The human clinic al evidence concerning health effects potentially associated with SO 2 is not indicative of adverse effects in the most sensitive population, exercising asthmatics, fr om exposure to short-term SO 2 peaks of less than 600 ppb. The epidemiological evi dence cannot determine that SO 2 is a cause of or a contributor to hospital admissions (“HA”), emergency department (“ED”) visits or respiratory symptoms, the effect s cited in the Proposed Rule. See 74 Fed. Reg. at 64818/1-2. Moreover, as demons trated in the REA, a 1-hour NAAQS in the range of 50 to 150 ppb would not reduce the risk of such e ffects in current ambient air. Thus, no such standard is requisite (or necessary) to protect the public health with an adequate margin of safety. Even if EPA rejects UARG’s advice on the lack of justification for a new standard, however, the Agency should m odify some aspects of its plans for implementing any new NAAQS. I. Scientific Information Does No t Demonstrate that Short-term SO 2 Concentrations Below 600 ppb Cause Po tentially Adverse Effects on Public Health. Section 109 of the Clean Air Act (“C AA” or the “Act”) requires the EPA Administrator (“Administrator”) to set primary NAAQS for ce rtain criteria pollutants, including SO 2 , at levels that in her judgment are “requisite to protect the public health” while “allowing an adequate margin of safety.” 42 U.S.C. § 7409(b)(1), CAA § 109(b)(1) (hereinafter, citations are given only to the Ac t). In determining what level is requisite to protect public health, she must consider the health of sensitive groups (or4 subpopulations), such as thos e with particular medical conditions and those in particular age groups, but not the most sensitive individuals within those groups. See S. Rep. 1196 at 10 (1970), reprinted in 1 A L EGISLATIVE H ISTORY OF THE C LEAN A IR A CT A MENDMENTS OF 1970 410 (1974) (“1970 Legis. Hist.”). Interpreting this congressional instruction not long after it was given, EPA established the initial NAAQS for lead at a leve l that it estimated w ould protect 99.5% of children under five years of age (which it iden tified as a the group most sensitive to lead exposure) against “potentially adverse” health effects. 43 Fed. R eg. 46246 (Oct. 5, 1978). At that time, EPA recognized that certain children might be at “enhanced risk” due to factors such as genetics, diet or re sidence, but did not tr eat them as an even more susceptible subgroup. See id. at 46252. The U.S. Court of Appeals for the District of Columbia u pheld the lead NAAQS. See Lead Indus. Ass’n v. EPA , 647 F.2d 1130 (D.C. Cir. 1980). Indeed, EPA has consis tently acknowledged that NAAQS are not intended to protect each member of a sensitive gr oup or subpopulation. 5 Further, Congress intended the NAAQS to pr otect the public against the risk of “adverse” health effects , 1970 Legis. Hist. at 410, not all health effects. EPA has therefore always set primary NA AQS at the level the Admini strator judges adequate to protect public health from onl y such adverse effects. See, e.g. 36 Fed. Reg. 8186, 8186/2 (Apr. 30, 1971) (noting that the Admini strator “has in each case promulgated a national primary stand ard which includes a margin of safety adequate to protect the public health from adverse effects suggested by the available data.”). The level for such5 a standard need not protect against all risks, only “significant” ones. See Ethyl Corp. v.
EPA , 541 F.2d 1, 12-32 (D.C. Cir. 1976). EPA has acknowledged that NAAQS are not to be “zero risk” standards. 6 In determining the significance of the risk posed by the pollutant (in this case SO 2 ) in the ambient air, the Admini strator must consider that risk in the context of the real world. Whitman v. Am. Trucking Ass’ns , 531 U.S. 457, 494-95 (2001) (Breyer, J., concurring in part and concurring in judgment). The Administrator must base her judgment concerning the adversity of effects and the significance of risks posed by a pollutant like SO 2 on air quality criteria that “adequately reflect the latest sci entific knowledge useful in indicating the kind and extent of all identifiable effects on human health . . . which may be expected from the presence of such pollutant in the ambient air in va rying quantities.” CAA § 108(a)(2). She may not set a NAAQS at a level that is more st ringent than necessary to protect public health with an adequate margin of safety. Whitman , 531 U.S. at 473, 476. In reaching her judgment, she must consider advice rece ived from CASAC but is not bound to follow that advice or draw the same conclu sions as drawn by that Committee. See CAA § 307(d)(3) (stating that if the Administrator’s proposal in a proposed rulemaking “differs in any important respect” from CASAC’s adv ice, the Administrator must include an explanation for such differences in the proposed rule); Am. Farm Bureau Fed’n v. EPA , 559 F.3d 512, 522 (D.C. Cir. 2009) (remanding but not vacating a rule on the PM

5 See, e.g. , 74 Fed. Reg. 34404, 34405 n.1 (July 15, 2009); 73 Fed. Reg. 16436, 16437 n.1 (Mar. 27, 2008); 71 Fed. Reg. 61144, 61145 n.1 (Oct. 17, 2006); 44 Fed. Reg. 8202, 8210/1 (Feb. 8, 1979).

6 See e.g., 62 Fed. Reg. 38856, 38857/2 (Jul y 18, 1997); 62 Fed. Reg. 38652, 38653/2 (July 18, 1997).6 NAAQS, holding that the Admi nistrator had failed to provide a sufficient explanation for not following CASAC’s advice, but stating that if the Agen cy could explain its decision adequately, it was free not to follow CASAC’s advice). Indeed, the Administrator may not del egate judgment regarding the requisite levels for the NAAQS to any person. CAA § 301. It is the Administrator who must “make a judgment as to the le vel of physiological response that should be considered adverse.” 50 Fed. Reg. 37484, 37496/1 (Sep t. 13, 1985). Additionally, when reviewing an existing NAAQS (which previously was de termined to be at the level requisite to protect human health according to the CAA), the Administrator must provide a reasoned explanation for any conclusion that the existing NAAQS is no longer at the level requisite to protect public healt h with an adequate margin of safety. 7
In the last review of the primary NAAQS for SO 2 , the Administrator concluded that no revision of the existi ng NAAQS was necessary at that time to protect public health. 61 Fed. Reg. 25566 (May 22, 1996) (“1996 NAAQS Rule”). Focusing on the same types of lung function changes and resp iratory symptoms in exercising asthmatics that are at issue in the current proceeding (i.e., increased specific airway resistance (“sRaw”), decreased forced expiratory volu me (“FEV”), and respiratory symptoms such as chest tightness, wheezing and shortness of breath), 8 the Administrator noted that

7 See Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co. , 463 U.S. 29, 42 (1983) (“an agency changing course by resci nding a rule is obligated to supply a reasoned analysis for the change beyond that which may be required when an agency does not act in the first instance”); Atchison, Topeka and Santa Fe Ry. Co. v. Wichita Bd. of Trade , 412 U.S. 800, 808 (1973) (an agency must “explain its departure from prior norms”); AT&T Corp. v. FCC , 263 F.3d 729, 736 (D.C. Cir. 2001) (reasoned decision making standard requi res explanation of departure from prior decision).

8 Id. at 25570/3.7 variability in lung function is a typical feature of asthma. 9 She recognized that lung function in asthmatics tends to be better at ce rtain times of the day than at others and may be affected by a variety of common stim uli, such as cold air, pollen and other allergens, which asthmatics encounter on a daily basis. 10 Exercise alone triggers bronchoconstriction in many asthmatics, a condi tion that is exacerbated if the exercise takes place in cold, dry (albeit clean) air. 11 Additionally, the Administrator noted that asthmatic responses to peak SO 2 exposure are transient -- unlike health effects associated with other stim uli, such as pollen, there are no “late phase” responses -- lung function typically returns to normal within an hour after exercise or exposure to SO 2 ends. 12 She also noted that the responses in asthmatics to SO 2 during exercise are “transient,” generally return ing to normal within an hour. Id. at 25570/3. Lung function started to improve if the ex ercise stopped, even if the SO 2 exposure continued. Id. at 25572/2. The Administrator concluded that “repeated occurrences” -- as opposed to a single incident -- of the re sponses of the more sensitiv e asthmatic subjects to SO 2 concentrations in the range of 0.6 to 1.0 ppm “should be regarded as significant from a public health standpoint.” Id. at 25573/3. 13 Taking into account the infrequent, localized

9 Id. at 25570/3.

10 Id. at 25570/2-3.

11 Id. at 25570/3.

12 Id. at 25570/3. The responses often diminished even as the SO 2 exposure and exercise continued. See Linn WS, Avol EL, Peng RC, Shamoo DA, Hackney JD. (1987) Replicated Dose-Response Study of Sulfur Dioxide Effects in Normal, Atopic, and Asthmatic Volunteers. Am. Rev. Respir. Dis. 136:1127-34, at 1129.

13 The Administrator noted that the effect s in asthmatics exercising in 0.6 ppm were more pronounced than those in asthmatics exercising in lower SO 2 (continued on next page)8 and site-specific nature of the responses, the Administrator concluded that revision of the NAAQS was not warranted. Id. at 25575/3. In response to a challenge of the 1996 NAAQS Rule by the American Lung Association and the Environmental Defense F und, the U.S. Court of Appeals for the District of Columbia Circuit held that the Administrato r is required to provide an explanation of her use of the discret ion delegated to her under the CAA. See Am. Lung Ass’n v. EPA , 134 F.3d 388, 392 (1998) (“Where . . . Congress has delegated to an administrative agency the critical task of a ssessing the public health and the power to make decisions of national import . . . that agency has the heaviest of obligations to explain and expose every step of its r easoning.”). The court remanded the 1996 NAAQS Rule to the Agency, not becaus e it disagreed with the Administrator’s interpretation of the scientific evidenc e, but because the Administrator had not explained adequately her judgment that the existing NAAQS we re requisite to protect public health, and therefore did not require revision. See id. at 392-93 (“[T]he Administrator may well be within her authority to decide that [the existing NAAQS is requisite to protect public health]. But unless she describes the standard under which she has arrived at this conclusion . . . we hav e no basis for exercising [judicial review] . . . . Given the gaps in the Final Decision’s r easoning, we must remand this case to permit the Administrator to explain her conclusions more fully.”). In the Proposed Rule, the Administrator fails to provide a reasoned explanation for changing course by now concluding that the existing NAAQS do not to protect public

concentrations. Id. at 25571/2. In addition to pointi ng to group mean decreases in FEV of 15% or greater at 0.6 ppm SO 2 , she pointed to sRaw incr eases of 200% or greater (continued on next page)9 health with an adequate margin of sa fety and require revision. See Motor Vehicle Mfrs Ass’n, 463 U.S. at 42

. She has not explained why the “latest scientific knowledge” now indicates an adverse effect on human heal th “which may be expected from the presence of [SO 2 ] in the ambient air.” CAA § 108(a)(2 ). She has failed to justify her conclusion that effects that were not considered adverse in 1996 should be deemed adverse now. A. New clinical evidence does not justif y a change in conclusions from the prior review. The Proposed Rule states that EPA’s conclusion that there is a causal relationship between respiratory morbidity and short term SO 2 exposure is based primarily on human clinical studies. 74 F ed. Reg. at 64816/2. The new clinical evidence presented in the ISA, however, does not represent a change in the character of the scientific evidence regarding effects of SO 2 exposure since the last review. 14 Rather, the changed conclusions ar e the result of changes in EPA’s interpretation of the evidence. Only if she can supply a “r easoned analysis” for these changes can the Administrator rely on them for a change to the 1996 conclusion that effects of public health significance begin at 600 ppb, or for a reversal of the 1996 decision that no new short-term NAAQS was needed to protect public health with an adequate margin of safety. She has failed to present such an analysis. See 61 Fed. Reg. at 25573/3. EPA’s definition in the Proposed Rule of what constitutes an adverse health effect is inconsistent with the definition of effects considered to be of public health

and FEV decreases of 20% or greater in some individuals. Id. at 25571/2.

14 See id. at 64816/3 (describing th e newer human clinical studies as “supportive” of the evidence considered in the last review).10 significance in 1996, and with the definitio n’s purported basis. The Administrator acknowledges that her definiti on of adversity is different fr om that in the 1996 review. Specifically: [W]hereas the conclusions in the prior review of the SO 2 NAAQS were based on SO 2 exposure concentrations which resulted in large decrements in lung function and moderate to severe respiratory symptoms, the ISA’s current review of data from controlled human ex posure studies focused on moderate to large SO 2 -induced decrements in lung function and/or respiratory symptoms ra nging from mild . . . to severe. 74 Fed. Reg. at 64816/2. The genesis of this change is obscure. First, the Proposed Rule seems to postulate that the health risk to asthmatics who experience lung function effects without symptoms might be greater than the health risk to t hose who experience both symptoms and lung func tion decrements. See id. at 64816/2. It is simply implausible that a failure to experi ence symptoms is worse than having them. Second, the Proposed Rule points to advice from CASAC as justificati on for the focus on moderate as well as large lung function decrements. Id. at 64817/3. But the Administrator culls this advice from comments of individual CA SAC members in the transcript of a CASAC meeting; it is not reflected in the letter from the complete CASAC that followed that meeting. Finally, the Administrator simply provides no explanation of why she now considers mild symptoms to be adv erse health effects. Clear ly, this does not constitute a reasoned analysis in suppor t of the change to the definition of adversity. The Administrator also states that the Agency’s definition of “adversity” is derived from a statement of the American Thoracic Society (“ATS”). See id. at 64816/3. In the Proposed Rule, however, EPA mischaracterize s and deviates substantially from the11 ATS adversity definition. According to ATS, “a small, transient loss in lung function, by itself, should not automatically be des ignated as adverse,” but should only be considered adverse when accompanied by symptoms. American Thoracic Society, What Constitutes an Adverse Heal th Effect of Air Pollution? , 161 Am. J. Respir. Crit. Care Med. 665, 670 (2000) (hereinafter “ATS Statement”). Additionally, ATS considers symptoms to be adverse at t he individual level when they decrease quality of life or cause a change in clinical status. Id. at 671. As quoted above, though, in the Proposed Rule and contrary to the ATS Statement, EPA states that it is treating lung function decrements accompanied by even mild symptoms to be adverse effects. 74 Fed. Reg. at 64816/3. With respect to adversity at the popul ation level, based on the ATS Statement, the Proposed Rule argues that “an air polluti on-induced shift in a population distribution of a given health-related endpoint (e.g. lung function) should be considered adverse, even if this shift does not result in the immediate occurrence of illness in any one individual in the population.” Id. at 64816/3. The Proposed Rule attributes this definition of an adverse effect to the ATS Statement. Howe ver, EPA is not applying the ATS Statement appropriately in this context. ATS gives the following illustration of its population level standard: A population of children wi th asthma could have a distribution of lung function su ch that no indi vidual child has a level associated with impairment. Exposure to air pollution could shift the distribution toward lower levels without bringing any individual child to a level that is associated with clinically relevant consequences . Individuals within the population would, however, have diminished reserve function and are at potentially increased risk if affected by another agent, e.g. a viral infection.12 ATS Statement at 668. The scenario that ATS sets forth does not apply to the risks associated with SO 2 exposure primarily for two reasons. Fi rst, when they occur, the effects of SO 2 exposure on exercising asthmatics (the sensitive subp opulation here, analogous to the asthmatic children in the ATS illust ration) are transient. See discussion supra at p. 7. As EPA has acknowledged, lung function returns to bas eline levels within an hour, when either exercise or SO 2 exposure ceases. Therefore, a detec table shift in the lung function of the asthmatic population would never occu r such that the popul ation would become more susceptible to other agents as a result of diminished reserve capacity. Moreover, variation in lung function is a characteristic of asthma. See supra at 6-7. Second, in evaluating the effects of SO 2 exposure on public health in th is review, the Administrator has focused on the responses of a small gr oup of individuals that has responded to lower levels of SO 2 than the rest of the exer cising asthmatic subjects. See, e.g., 74 Fed. at 64842/2. As described infra at p. 14-15, there is no indication that these individuals are a distinct s ubpopulation that may be affected in the manner described in the ATS Statement. It is unclear why the Administrator di verges from the guidance of the ATS Statement in determining adver sity at the individual level or why she applies ATS’s definition of adversity at t he population level, without explanat ion, to a scenario to which the definition is not applicable. It appear s that she may be interpreting the ATS Statement in a manner that supports her ow n speculation about the scientific research. Indeed, the Administrator’s conclusions in the Proposed Rule are based in large part on speculation. The range of possible le vels for the proposed 1-hour NAAQS in the13 Proposed Rule is justified in part on the basis that the participants in the clinical studies are most likely not the mo st severe asthmatics, see id. at 64844/2, and that more severe asthmatics may respond to lower levels of SO 2 . There is a significant legal problem with the Agency’s reasoning -- the Ad ministrator’s judgment must reflect the “latest scientific knowledge” regarding the relevant health effects from SO 2 in the ambient air, CAA § 108(a)(2), and she may not base her judgment on speculation. Am. Petroleum Inst. v. Costle , 665 F.2d 1176, 1186-87 (D.C. Cir. 1981) (“[T]he Administrator’s conclusions must be support ed by the record, and [s]he may not engage in sheer guesswork.”). It is clearly speculat ive for the Administrator to base the level of the proposed NAAQS on the idea that individual s with asthma more severe than those that participated in clinical studies may expe rience health effects at lower levels -- there is nothing to support the idea that more seve re asthmatics are likely to respond to lower levels of SO 2 -- in fact, there is evidence to the contrary. There is published, peer-reviewed clinic al evidence that, among asthmatics, responses to SO 2 exposure are not dependant on the clinical severity of asthma. Linn, et al. (1987) tested the effect of SO 2 exposure on lung function in exercising asthmatics, including a group of “minimal/mild” as thmatics and a group of “moderate/severe” asthmatics, and found that responses to SO 2 were not predictable based on either the severity of the disease or the subjects’ tolerance for exercise. 15 In fact, the Linn study concluded that “the subjects at highest risk [of temporary respiratory disturbances from

15 Linn WS, Avol EL, Peng RC, Shamoo DA, Hackney JD. (1987) Replicated Dose-Response Study of Sulfur Dioxide Effects in Normal, Atopic, and Asthmatic Volunteers. Am Rev Re spir Dis 136:1127-34.14 ambient SO 2 ] can be identified only by actually measuring their responses to SO 2 .” 16 EPA is aware of the Linn study -- it is cited in the Proposed Rule to support the proposition that SO 2 -induced responses for individuals ar e reproducible. 74 Fed. Reg. at 64824/2. Thus, the Administrator acknow ledges the portion of Li nn’s findings that seems consistent with her speculation -- that an asthmatic participant’s sensitivity to SO 2 exposure was predictable on an individual basis (the same participants were shown to exhibit the same level of sensitivity to SO 2 in repeated trials) -- but ignores Linn’s main finding -- that an asthma tic participant’s sensitivity to SO 2 exposure was not predictable based on the severity of the parti cipant’s asthma. The inappropriateness of the Administrator’s speculation, therefore, is exacerbated by the fact that she ignores scientific evidence that contradicts her assumption. The Proposed Rule also states that EPA believes that 200 ppb does not represent a threshold below which adverse effects do not occur, based only on the fact that a relatively small percentage (5-30% ) of exercising asthma tics experienced lung function decrements at 200-300 ppb, the lowest level tested in chamber studies. Id. at 64822/1. The Administrator’s reliance on her assumption that some asthmatics will respond to SO 2 exposure at levels lower than other asthmatics is also contrary to congressional intent. As mentioned above, in setting the NAAQS, the Administrator must consider the health of sensitive s ubpopulations, but not the most sensitive individuals within those subpopulations. See discussion supra at p. 3-4. Asthmatics are a distinct subpopulation definable by biological criteria, a nd it is appropriate for the Administrator to consider the unusual susceptibility of asthmatics to SO 2 exposure in

16 Id. at 1132.15 setting the standard. However, it is beyond her authority to base her judgment on a consideration that certain individuals respond to lower levels of SO 2 . These “responders” are not a sensitive subpopulation; they are merely individuals with no identifiable common characteri stics. Even ATS recognizes that “[r]esearch now shows that some highly susceptib le individuals may respond to common exposures that are often unavoidable . . . [and that ] by definition, susceptible individuals cannot have the same margin of safety as the nonsuscept ible groups within the population.” ATS Statement at 669. It is inappropriate for the Administrato r to consider these responders and to extrapolate from individual results to assume without evidence that these responders are part of some uni dentified subpopulation. In short, the Administrator has not provided a reasoned explanation for her definition of what constitutes an adverse hea lth effect for purposes of interpreting the evidence from human clinical studies. Re sponses of exercising asthmatics to SO 2 exposure in recent studies merely suppor t the findings of studies considered in promulgating the 1996 NAAQS Rule. Indeed, the lowest SO 2 concentration that arguably represents a public heal th concern among exercising asthmatics continues to be 600 ppb, as it was in 1996. The Administrator’s speculation in the Proposed Rule that there may be a population of severe asthmatics or subs et of asthmatics that is more sensitive to exposure at lower SO 2 concentrations is unavailing. The clinical studies do not support a conclusion that even exercising asthmatics require protection from brief SO 2 exposures below 600 ppb.16 B. New epidemiological evidence does not justify change in conclusions from prior review The Proposed Rule states that in addition to clinical studies, “the ISA based its causal finding of an association betw een short-term . . . exposure to SO 2 and respiratory morbidity on result s from epidemiologic studies of respiratory symptoms, as well as [emergency department] visits and hospit alizations for all respiratory causes and asthma.” 74 Fed. Reg. at 64818/2-3. Although the Proposed Rule acknowledges uncertainties with respect to the epidemiologic studies, it fa ils to account fully for the nature and magnitude of uncertain ty that surrounds the epidemiologic research. This failure has persisted throughout the current review of the SO 2 NAAQS. As a result, although the epidemiologic research cites health e ffects, such as HA and ED visits, that are unquestionably adverse, there is no clear indi cation that these effe cts are the result of SO 2 exposure. In fact, there is evi dence to suggest that they are not. The epidemiologic studies cited in the Proposed Rule are inconsistent with the results of clinical studies. The Proposed Ru le states that “[e] pidemiologic studies provide evidence of associations between SO 2 concentrations and more serious health endpoints (e.g., [HAs] and [ED visits]) that cannot be assessed in controlled human exposure studies.” Id. at 64815/3. This statement is curious. Although no one would suggest that clinical studies could or s hould be conducted with the intent of sending people to the hospital, there is also no indi cation from the clinical studies of any population that would be susceptible to SO 2 such that a brief exposure to a low concentration could lead to hospital visits. As discussed above, research indicates that responsiveness to SO 2 in asthmatics is not dependant on the severity of the asthma. See discussion of Linn et al. (1987) supra at p. 13-14. Additio nally, clinical studies17 conducted at SO 2 concentrations far above ambient levels 17 report only effects in asthmatics that are transient and revers ible and that dissipate rapidly. See supra at p. 7. EPA recognizes that human clinical studies “provide directly applicable information for determining causality” while for epidemio logical studies “the degree of uncertainty introduced by confounding variables (e.g., ot her pollutants) affects the level of confidence that the health effects bei ng investigated are attributable to SO 2 exposures.” 74 Fed. Reg. at 64815/3 - 64816/1. Thus, the discrepancy between the nature of effects attributed to SO 2 in epidemiologic studies at ambi ent levels and those in clinical studies at much higher SO 2 concentrations must call into question the reliability of the epidemiological studies as evidence of effects from SO 2 exposure. Although EPA acknowledges that confoundi ng is an issue in epidemiologic research, the Agency fails to account for it appropriately. As epidemiologic studies are observational in nature, confounding by co -pollutants and other environmental factors can never be ruled out, but researchers c an evaluate the possibi lity of confounding through the use of co-pollutant models. Ho wever, many of the epidemiologic studies that EPA relied on for the conclusions drawn in the ISA and that the Administrator cites as “key studies” in the Proposed Rule fail to account for confounding. For example, of the five epidemiologic studies cited in the Proposed Rule that studied respiratory symptoms, none appropriately accounted for c onfounding. The Proposed Rule states that the results of Mortimer et al. (2002) and Schildcrout et al. (2006) “remained robust and statistically significant” in co-pollutant models. Id. at 64818/2, 3. However, both of

17 Clinical studies show pronounced, though tr ansient, effects following exposure to SO 2 concentrations beginning at 0.6 - 1.0 ppm (600 - 1000 ppb). 61 Fed. Reg. at (continued on next page)18 these studies used regional monitoring as a surrogate for exposure, which leads to measurement errors in the estimate of SO 2 exposure, but also in exposure estimates for all of the other potentially confounding co-pollutants. 18 When all of the co-pollutants are measured with error, robustness of the association of one pol lutant in multi-pollutant models is not sufficient to infer an absence of confounding. Schwartz et al. (1994) found that there was a possi bility of confounding by PM 10 . See id. at 8; 74 Fed. Reg. at 64818/3. Neither of the other two studies in cluded multi-pollutant models. 74 Fed. Reg. at 64818/3. Likewise, only thr ee of the ten “key studies” on HAs and ED visits included multi-pollutant models, and mult i-pollutant models in those three studies reported mixed results. See id. at 64819/2-3. It is particularly i nappropriate to rely on such studies when, as here, EPA has previously concluded t hat the very effects investigated in the studies are caused by co-pollutants. 19 Another issue with the treatment of epidem iologic research in the Proposed Rule is the lack of statistical significance in many of the studies cited. Although the Administrator notes the importance of the strength of statistical associations in

25571/3.

18 See J. Turim, Ph.D., C. Frankenfeld, Ph.D., S. Moolgavkar, M.D., Ph.D., Comments on EPA’s Integrated Sc ience Assessment for Sulfur Oxides-Health Criteria (Second External Review Draft) (July 25, 2008) at 7-8, attached as Enclosure 1 to Second Draft ISA Comments (“Turim 2007”).

19 Each of the Agency’s 2006 PM 2.5 NAAQS, 2008 ozone NAAQS, and 2010 NO 2 NAAQS are based, at least in part, on epidemi ologic evidence associating each of those pollutants with HAs and ED visi ts for respiratory causes. See National Ambient Air Quality Standards for Particulate Matter; Fi nal Rule, 71 Fed. Reg. 61143, 61145/1 (Oct. 17, 2006); National Ambient Air Quality Standards for Ozone; Fi nal Rule, 73 Fed. Reg. 16436, 16436/3 (Mar. 27, 2008); Primary National Ambient Air Quality Standards for Nitrogen Dioxide: Final Rule (Jan. 22, 2010), at 24.19 epidemiologic studies, 74 Fed. Reg. 64816/1, she relies heavily on studies where there is no statistically significant association. See, e.g. , id. at 64819/1 (“Taken together, [the ten “key” epidemiologic studies on HAs and ED visits] generally reported positive, but frequently not statistically significant associations between ambient SO 2 and ED visits and [HAs] for all respiratory causes and for as thma.” (emphasis added )). This lack of statistical significance indicates a likelihood th at the positive results of these studies are inaccurate, and they may well be indi cating no effect at all. Finally, EPA has failed to address recent st udies relevant to the health effects of SO 2 exposure, even after UARG called them to the Agency’s attention over two years ago in its comments on the first draft of the ISA. 20 These studies, which EPA has failed to account for in this NAAQS review, r eported results that counter the Agency’s conclusions regarding the health effects of SO 2 exposure. For example, Donoghue and Thomas reported “no evidence of any positive relation between peak SO 2 concentrations [ranging from 0 to 8700 μ g/m 3 ] and hospital presentations or admissions for asthma, wheeze or shortne ss of breath.” Donog hue et al. (1999) at 232. Erbas and Hyndman examined the sensitivity of asso ciations between air pollution and HAs and reported that “the effe cts of . . . sulfur dioxide we re highly sensitive to model specification for both COPD and asthma [HAs].” S ee Turim 2007 at 10.

20 See First Draft ISA Comments at 10 n. 28 (noting that neither Erbas, B & Hyndman, RJ (2005) Sensitivity of the esti mated air pollution-respiratory admissions relationship to statistical model choice. Int. J. Environ. Health Res. 15:437-48 nor Donoghue, AM & Thomas M (1999) Point s ource sulphur dioxide peaks and hospital presentations for asthma. 56 Oc cup. Environ. Med. 56:232-36 is discussed in the ISA). Neither study was mentioned in subsequent drafts of the ISA or the REA, and neither is mentioned in the Proposed Rule.20 EPA is required to consider all of the “lat est scientific knowledge ” relevant to the effects of SO 2 exposure on human health. CAA § 108(a)(2). It is just as important that EPA consider scientific research such as this, t hat indicates that ther e is no effect, as it is that the Agency consider research that indicates an effect -- the Agency must examine the entire range of outco mes in order to formulate a judgment that reflects the latest scientific knowledge. The fact that EPA has failed to examine, or even acknowledge the existence of these studies after they were pointed out in public comments, is a striking indication that EPA has not fulfilled it s duty under the CAA. II. Information on Both Exposure and Risk Demonstrates No Need for the Proposed 1-hour SO 2 NAAQS. As discussed above, the Administrator is required to set primary SO 2 NAAQS at a level that in her judgment is “requisite to protect the public he alth” while “allowing an adequate margin of safety.” CAA § 109(b)(1). In determining what level is requisite, she must base her judgment on air quality cr iteria that “adequately reflect the latest scientific knowledge useful in indicating the ki nd and extent of all identifiable effects on human health . . . which may be expected from the pres ence of such pollutant in the ambient air in varying quantities.” CAA § 108(a)(2 ) (emphasis added). In other words, the Administrator must set the NAAQS at a level that is necessary to protect public health from risks presented by exposure to SO 2 in the ambient air, at levels that exist at the time of the review or t hat are expected to exist in th e future. In doing so, she may not set the NAAQS at a level that is more stringent than necessary to protect public health with an adequate margin of safety. See Whitman , 531 U.S. at 473, 476 (2001). According to information provided by EPA, there is no unacceptable risk to public health posed by current ambient levels of SO 2 and none is expected in the future. In21 effect, the Proposed Rule s eeks to fix a problem that does not exist. EPA has acknowledged repeatedly that SO 2 concentrations in the United States have been decreasing over the past several decades and that it expects this trend to continue. EPA reported in December 2009 that, as of 2008, annual SO 2 emissions had decreased by 56% compared with 1980 levels and 52% co mpared with 1990 levels. EPA, Acid Rain and Related Programs: 2008 Highlights, 2 (Dec. 2009). Additionally, the national composite average of the annual m ean ambient concentration of SO 2 decreased by 71% between 1980 and 2008. 21 Id. at 5. In EPA’s most recent National Air Quality Status and Trends Report, the Agency ci ted a downward trend in ambient SO 2 concentrations. EPA, National Air Quality Status and Trends Through 2007, 27 (Nov. 2008). The Agency attributed this trend to va rious national emissions control programs, including the NAAQS, and stated that it expects air quality to continue to improve in the coming years. Id. at 3, 27. Accordingly, any existing health risks from SO 2 exposure will be expected to decline in the future. Significantly, however, EPA has not identif ied any health risks from exposure to current ambient concentrations of SO 2 . Although the REA and the Proposed Rule include some information on risks at current ambient levels of SO 2 , both the REA and the Proposed Rule focus on risks that would exis t if air quality were adjusted to just meet the current NAAQS (either the 24-hour standard or the annual standard, whichever is controlling for a particular area) and to just meet pot ential alternative onehour daily maximum standards of 50, 100, 150, 200 and 250 ppb respectively.

21 EPA specifically noted that the decline in SO 2 emissions from the power industry has improved air quality. Id.22 Throughout this NAAQS review process, UARG has commented repeatedly that EPA should base its analyses on the effects of current air quality and not air quality modeled to just meet the current standard or alte rnative standards. 22 There are a number of serious issues with EPA’s use of modeled air quality. First, as described above, the Administrator, in reviewing and re vising the NAAQS, is required to consider risks to public health associated with air qua lity under current conditions or conditions that are expected to exist in the future. EPA has been quite clear that current air quality has improved dramatically over the past se veral decades and that it is expected to continue to improve in the future. See discussion supra at p. 20-21. It is far better than needed to meet the current NAAQS in all but three areas in the continental United States. 23 Thus, ambient SO 2 concentrations are not expect ed to increase to just meet the current standard in the futu re, and setting aside the fact that EPA has stated that it expects SO 2 concentrations to continue decreasing, EPA has not identified any event or condition that could lead to a deteriorati on of air quality that would cause ambient SO 2 concentrations to reach the current NAAQS. Although they are not reported in t he Proposed Rule and apparently were not considered in the preparation thereof, the REA contains so me data that address risk at current air quality. EPA has stated that the pur pose of the proposed 1-hour standard is to protect against 5-minute SO 2 concentrations above 200 to 400 ppb. 74 Fed. Reg. at

22 See First Draft REA Comments at 3-9; Se cond Draft REA Comm ents at 4-9.

23 See , EPA’s Green Book nonattainment areas for sulfur dioxide (primary standard), available at http://www.epa.gov/oar/oaqps /greenbk/snc.html (listing Armstrong County, PA, Hayden (Pinal C ounty), AZ and Laurel Area (Yellowstone County), MT as nonattainment area for the primary SO 2 NAAQS.23 64842/3; REA at 392. Thus, this is the le vel of risk that the Administrator has determined to be acceptable. 24 However, EPA’s evaluation of data from 809 ambient SO 2 monitors, given the annual average SO 2 concentration between 1997-2006, reported that only approx imately 1% of days included a 5-minute SO 2 concentration of 200 ppb, and less than 1% of days included a 5-minute SO 2 concentration of 300 or 400 ppb. REA at 127-28. Thus, 5-minute SO 2 concentrations in the range of interest are very rare, and health effects can only be related to such infrequent SO 2 levels if susceptible people (in this case, sensitive exercising asthmatics) are exposed to such levels. Additionally, as air qua lity is improving, 5-minute SO 2 concentrations in this range are likely to be even lower today. EPA’s REA included risk and exposure analysi s case studies of asthmatics -- the subpopulation that EPA has identified as susceptible -- in St. Louis and in Greene County, Missouri. The Agency examined spec ifically the number of asthmatics living within 20 kilometers of a major SO 2 source experiencing 5-minute SO 2 exposures to 100, 200, 300 and 400 ppb while at elevated br eathing rates, and modeled air quality to represent attainment of eac h of the targeted levels. Id. at 10. EPA reported that the exposure results for Greene County using “as is ” air quality were sim ilar to those for air quality adjusted to meet the proposed 99 th percentile 1-hour daily maximum standards of 50 and 100 ppb, with few people being exposed, and that the results for St. Louis indicated that exposure results for “as is” air quality were within the range of exposures using the proposed 50 and 100 ppb standards. Id. at 312.

24 The NAAQS is not intended to eliminate all risk. See discussion supra at p. 4- 5.24 EPA’s risk modeling indicates that the risks associated with current ambient air quality are consistently compar able to or lower than the risks that are estimated to exist upon attainment of an y of the 1-hour SO 2 standards under consider ation. For example, Table 9-8 of the REA presents EPA’s data on the percentages of asthmatic children engaged in moderate or gr eater exertion that are estimat ed to experience at least one lung function response per year associated with exposure to SO 2 concentrations at various levels in each of St. Louis and Greene County, Missouri. See id. at 338. Table 9-8 of the REA is reproduced below:

As indicated in Table 9-8, EPA’s St. Louis analysis reported that, using the 2- parameter logistic model, the percentage of asthmatic childr en engaged in moderate or greater exercise who are estimated to ex perience an increase in specific airway resistance (sRAW) of 100% or gr eater at least once in a year from exposure to current ambient air is 1.4%, which is lower than the percentage of ch ildren estimated to25 experience such a response upon ex posure to air that meets a 99 th percentile daily maximum 1-hour standard of either 100 ppb (2 .9%) or 150 ppb (5.4%). Although the percentage estimated to experience such a response upon exposure to air that meets the 50 ppb standard appears slightly lower (0.9 %), it is indisti nguishable from the percentage responding to current air quality, as it falls within the 95% credible interval (0.5% - 3.8%). The same is true using the probit model, with 0.8% estimated to respond following exposure to current air quality, compared to 2.1% and 4.6% estimated to respond following exposure to ai r meeting either of the proposed 100 or 150 ppb standards respectively, and 0.4% esti mated to respond following exposure at the proposed 50 ppb level (which is within the 95% credible interval of 0.2% - 2.8%). Similarly, the Greene County analysis report ed that, using either the 2-parameter logistic model 25 or the probit model, 26 the percentage of asthmatic children predicted to experience an increase in sRAW of 100% or great er at least once in a year is identical for current air quality, and for air quality that attains a 99 th percentile daily maximum 1- hour standard of 50 ppb, and lower with current air quality than with a 99 th percentile daily maximum standard of 100 ppb, or 150 ppb. Indeed, EPA’s modeling indicates that the comparability among the levels of residual risk permitted by current air quality and

25 According to EPA, in Greene County, 0. 4% of exercising asthmatic children would be expected to experience at least one lung function response associated with SO 2 per year following exposure to current air quality and following exposure to air meeting the 50 or the 100 ppb standard, and 0.5% would be expected to experience such a reaction upon exposure to air meeting the 150 ppb standard.

26 According to EPA, in Greene County, 0. 1% of exercising asthmatic children would be expected to experience at least one lung function response associated with SO 2 per year following exposure to current air quality or air m eeting the proposed 99 th percentile daily maximum 1- hour standard of either 50 or 100 ppb, and 0.2% would be expected to respond to air meeting the 150 ppb standard.26 by the proposed 1-hour standards of 50, 100 and 150 ppb holds true for EPA’s estimates of the number 27 and percent 28 of asthmatics engaged in moderate or greater exertion estimated to experienc e an increase in sRAW of 100% or greater at least once in a year; the number of occurrences of such an increase in sRAW among asthmatics; 29
the number of asthmatic children estimated to experience such an increase in sRAW; 30
and the number of occurrences of such an increase in sRAW among asthmatic children. 31 The same is also true of EPA’s estimates of decreases in FEV 1 of 15% and 20% following exposure to current air qualit y and air adjusted to meet the proposed 1- hour standards of 50, 100 and 150 ppb, which appear in Appendix C. 32

27 See id. at 334, Table 9-4.

28 See id. at 335, Table 9-5.

29 See id. at 336, Table 9-6.

30 See id. at 337, Table 9-7.

31 See id. at 339, Table 9-9.

32 See REA Appendix C at 4-18, Table 4-3 (number of occurrences in a year among asthmatics engaged in moderat e or greater exertion); 4- 19, Table 4-4 number of occurrences in a year among asthmatic children engaged in mode rate or greater exertion); 4-22, Table 4-7 (number of asthmatics engaged in moderate or greater exertion estimated to experi ence one such response in year); 4-23, Table 4-8 (number of asthmatic children engaged in moderate or greater exertion estimated to experience one such response in year); 4-26, Table 4- 11 (percent of asthmatics engaged in moderate or greater exertion estimated to ex perience one such response in year); and 4-27, Table 4-12 (percent of asthmati cs engaged in moderate or greater exertion estimated to experience one such response in year). In each case, the number or percentage estimated for current air quality is indistinguishab le from or lower than the number or percentage estimat ed for air quality adjusted to meet the proposed 1-hour standards of 50, 100 and 150 pp b (or the number or perc entage for the proposed standard is within the 95% credible interval for the estimate at current air quality).27 Moreover, EPA overestimates the risk to the health of asthmatics and asthmatic children associated with current air quality an d attainment of any of the alternative standards as a result of the techniques used in the analysis. 33 In addition, the Agency’s analysis fails to reflect that only repeated ex posures or lung function changes should be deemed to be of public health significance. It is important to note that, although the REA is not a comprehensive examination of risk nationally, it examined risks in areas where SO 2 emissions were among the highest currently found in the U.S. R EA at 189 (“In a rankin g of estimated SO 2 emissions reported in the National Emi ssions Inventory . . . Missouri ranked 7 th out of all U.S. states for the number of stacks with annual emissions greater than 1,000 tons.”). Additionally, the estimates of current ai r quality are actually based on air quality information from 2002. Id. at 332. Thus, these numbers ar e not representative of the United States now that SO 2 levels have fallen and likely overstate current risks. Even within this limited Missouri data set, EPA consis tently emphasizes the results of the St. Louis analysis and disregards the results of the analysis in rural Greene County. 34 This

33 See Memorandum from Edmund Crouch, Ph.D., to Utility Air Regulatory Group, Response to EPA-HQ-ORD-2006-02 60-0036 3-4 (Feb. 5, 2010) (Attached hereto as Attachment C) (e xplaining that EPA has failed to respond in any meaningful way to his technical comments on the draft REA on behalf of UARG, detailing substantial technical errors that led to si gnificant overprediction of risk, and that EPA has failed to account properly fo r such overprediction of risk).

34 See, e.g. , 74 Fed. Reg. at 64827/2 (“when c onsidering the risk and exposure results as they relate to the adequacy of th e current standards, t he REA concluded that the St. Louis results were more informative [than the Greene Co unty results] in terms of ascertaining the exte nt to which the current standards protect against effects linked to various benchmarks”); Id. at 64842/3 to 43/1 (basing determination of the level of the proposed 1-hour standard on the St. Louis risk and exposure analyses but not mentioning the Greene County analyses).28 is inappropriate. As indicated in the REA, 35 Greene County is a reasonable model for exposures in rural areas. In summary, as described above, in the REA and the Proposed Rule, EPA has vastly overestimated the public health risk presented by SO 2 concentrations. In fact, risks are below those ident ified by EPA as dangerous, or unacceptable, and will continue to decrease as air quality continues to improve. Theref ore, there is no justification for the proposed 1-hour NAAQS. 36 III. The Agency Must Base Nonattainment Decisions on Monitors Qualifying as Federal Reference Method Monito rs Under The Agency’s New Specifications. In the Proposed Rule, the Administrato r proposes to establish a new Federal Reference Method (“FRM”) for meas uring ambient levels of SO 2 , 74 Fed. Reg. 64846/1, and to update the performance based requirem ents for Federal Equivalent Method (“FEM”) analyzers. Id. at 64847/1. She proposes further to retain the current FRM for a period of time after the final rule (including the new FRM) is promulgated in order to

35 See, e.g. , REA at 311 (noting that the St. Louis and Greene County exposure analyses “[t]aken together . . . provide usef ul insights about urban and rural counties with SO2 emission sources”).

36 The health evidence at most suggests that exercising asthmatics should be protected from brief exposures to 600 ppb. Assuming that the ratio between a 5-minute peak and a 1-hour average is in the range of 2 or 3 to 1, an hourly standard in the range of 200 to 300 ppb would appear protective . Any such standard should use the 98 th percentile form given that only multiple responses by an asthmatic to SO 2 might legitimately be considered of public heal th significance. Moreover, the 98 th percentile form would be consistent with the form us ed for the Agency’s recently promulgated 1- hour primary NAAQS for NO 2 and the Agency’s 24-hour primary NAAQS for PM 2.5 . No such standard is requisite to protect public health, however, because SO 2 levels currently found in ambient air are alr eady protective against such effects.29 avoid disruption of the SO 2 monitoring network. Id. at 64848/1-2. Wh ile UARG agrees that a new FRM for judging co mpliance with a new 1-hour SO 2 NAAQS is appropriate, the proposed approach for implementing it is c ontrary to the term s of the CAA, and therefore must be abandoned. The Proposed Rule acknow ledges that any data to be used in determining compliance with the SO 2 NAAQS must be collected using either an FRM or an FEM. Id. at 64846/1. One primary purpose of FRMs is “to provide a s pecified, definitive methodology for routinely measuring concentrat ions of various ambient air pollutants for comparison to the NAAQS. Id. at 64846/2. An FRM is designated is to ensure consistency and fairness when judging co mpliance with a NAAQS. Thus, EPA designates a single FRM for judgi ng compliance with each NAAQS. 37 Therefore, if the Administrator promulgates a new 1-hour NAAQS for SO 2 , she must specify a single FRM for that standard, and only data collected using that FRM (or monitors designated as an FEM with regard to the FRM) can be used to assess compliance with that NAAQS. 38

37 See 40 C.F.R. App. A (specifyi ng a single FRM for the SO 2 NAAQS codified in 40 C.F.R. 50.4 & 50.5), App. C (describ ing a single measurem ent principle and calibration procedure defining an FRM for th e carbon monoxide NAAQS codified in 40 C.F.R. 50.8), App. D (descr ibing a single measurement principle and calibration procedure defining an FRM fo r the ozone NAAQS codified at 40 C.F.R. 50.9, 50.10 & 50.15), App. G (specifying a single FRM for the lead NAAQS codified at 40 C.F.R. 50.12 & 50.16) and App. L (specifyi ng a single FRM for the PM 2.5 NAAQS codified at 40 C.F.R. 50.7 & 50.13).

38 EPA would have the option of retaining the existing FRM for judging compliance with the 3-hour, 24, hour and annual NA AQS to the extent that any or all of those standards are retained. Certainly, EPA has designated different FRMs for measuring different regulated forms of parti culate matter. It might be less burdensome for the States, however, for EPA to des ignate a single FRM for all of the SO 2 NAAQS.30 With regard to EPA’s decision to use a different FRM to judge compliance with any new SO 2 NAAQS, UARG agrees that that is appropriate. The ability of this monitor to accurately measure low hourly concentrations of SO 2 has not, to UARG’s knowledge, ever been demonstrated. In fact, as the Proposed Rule explains: The existing FRM is primarily a 24-hour integrated method, whereas a 1-hour SO 2 FRM measurement capability would be needed to implement the proposed 1-hour SO 2 NAAQS. . . . While the existing manual reference method can produce 1-hour averages, it is clearly im practical for routine use in making 1-hour SO 2 measurements. Al so, the 1-hour mode of the manual methods is no t a good standard for approving new FEMs with 1-hour measurement capability, because scores of 1-hour measurem ents would be needed during equivalency testing

. 74 Fed. Reg. at 64846/3. The proposal to specify a different FRM to judge compliance is therefore entirely reasonable. UARG is generally supportive of the proposed specifications for a new FRM. We question, however, the Agency’ s proposed total interferent limit. EPA proposed to reduce the allowable interferenc e equivalent limits fo r the total of all interferents from 60 ppb to 20 ppb. Id. at 64848/3. Although this is a substantial reduction, even 20 ppb is a significant perc entage of any of the 1-hour NAAQS that EPA
proposes. 39 UARG therefore recomm ends that the Agency further limit the total of all interferents. 40

39 The Administrator’s proposed total inte rferent limit of 20 ppb amounts to 20- 40% of the proposed NAAQS (5 0-150 ppb). Eric S. Edgert on, Comments on Proposed SO 2 Rule 1 (Feb. 3, 2010) (Attach ed hereto as Attachment D).

40 See id. (demonstrating that the Administrator’s proposed total interferent limit is likely to lead to false positive exceedances of the proposed NAAQS).31 As EPA recognizes, specification of a new FRM has implications for existing SO 2 monitoring networks. See 74 Fed. Reg. at 64848/3. Fo r the reasons discussed above, however, EPA’s proposal to retain the existing FRM for several years -- thus having two FRMs specified for a given NAAQS -- is not viable. See id. at 64848/2. Although EPA states that the existing FEMs t hat constitute the bulk of the SO 2 monitoring network “are adequate for the current and the proposed SO 2 NAAQS,” Id. at 64848/1, the Agency has provided no support for th is statement. Although they may be adequate “for many other purposes,” Id. at 64848/1-2, they may only to used to judge compliance with the 1- hour NAAQS if they are shown to qualif y as FRMs or FEMS under the new FRM definition. EPA therefore would have two options for making initial designations with regard to any 1-hour NAAQS that it adopt s. First, it could designate all areas as unclassifiable until adequate data have been collected using the new FRM. Second, if the Agency believes that many of the monitors in the existing networks might qualify as new FRMs or FEMs, the Agency could take advantage of its authority to extend the deadline for designations by a year, see CAA § 107(d)(1)(B), 41 and use that year to determine which monitors would qualify under the new FRM and FEM definitions. For those monitors that qualify, EPA could then appropriately rely on existing data to make designations.

41 EPA recently used this provision to defer designations for the 2008 ozone NAAQS by a year while it re considers that rule. 75 F ed. Reg. 2936 (Jan. 19, 2010). Extending the date for designations in light of the lack of data fr om monitors then qualified as FRMs or FEMs would be at l east as appropriate as that use of the provision.32 IV. Other Implementation Concerns A. Monitoring Network Design EPA proposes to revise the design of the monitoring network for SO 2 to reflect two components: (1) a requirement for moni toring tied to an EPA-developed populationweighted emissions index based on populations and the em issions inventory of a CBSA, and (2) monitoring tied to total state-level SO 2 emissions. See 74 Fed. Reg. at 64851/2 to 53/3. UARG’s primar y concern with this network design is its reliance on old emissions data. For electric utilities which report their SO 2 emissions to EPA annually, the use of more recent data would be appropriate. UARG believes that it is appropriate to tie the monitoring network for a standard intended to protect public healt h to the size of the population in an area, as opposed to the alternative approach to network design on which EPA is soliciti ng comments. That approach would appear to focus solely on monitoring near SO 2 sources. See id. at 64854/3. Moreover, that approach would be laborious. It would rely on highly conservative screening models for selecting which sources might require a monitor, and would then require further modeling with AE RMOD to site monitors. EPA recognizes that AERMOD will likely require adjustments before it would be suitable for use with a new 1-hour SO 2 standard. Id. at 64862/1. More basically, however, AERMOD would simply not be appropriate for siting a monitor at the likely site of the expected maximum 1-hour concentration -- the model has been validated by compari ng it with observed high ambient concentrations, but its perform ance for matching concentrations at a specific time or location has not been evaluated.33 B. Data Interpretation The Proposed Rule also contains provisions to ensure data completeness. See Id. 64856/2-3. These provisions suggest that at least 75% of the monitoring data that should have resulted from monitoring in a ccordance with the schedul e during a calendar quarter must be available. Id. 64856/2. If it is not, but 50% percent of the expected data is available, the Administrator’s pl an “would substitute a high hypothetical concentration for as much of the mi ssing data as needed to meet the 100% requirement.” Id. at 64856/3. The concentrations t hat would be substituted would be the highest daily maximum 1-hour concentra tion observed during the same calendar quarter. Id. 64856/3. Finally, the Proposed Rule w ould give the Administrator “general discretion to use incomplete data,” either at the request of a st ate or on her own. Id. at 64856/3. UARG agrees that there should be comple teness criteria for compliance data. However, there are several flaws with the Ad ministrator’s approach. First, giving the Administrator authority to use incomplete data despite the rule on data completeness renders the rule meaningless and opens the po ssibility of arbitrar y decisions, or decisions that appear arbitrar y. The rule should incl ude a system for determining the circumstances under which incomplete data should be used, rather than giving unfettered discretion to the Administrator. Second, substituting the highest reported concentrations for missing data will lead to data sets that are not representative of actual conditions. If the rule provides fo r substitution of hypothet ical data, those data should be set at values that would have been likely to be recorded and not at extreme values. Third, given that only 75% of t he expected data are required for completeness, if hypothetical data are substituted, onl y enough to make up 75% of the expected data34 should be substituted, as opposed to 100%. The goal of the monitoring program should be to obtain an accurate measurement of ambient SO 2 levels and the measurement will be more accurate, not only the higher the per centage of expected data points are used, but also the higher the percent age of such data points that represent actual monitored data. C. Exceptional Events The Proposed Rule provides further that, with respect to exceptional events, to the extent 2011 data is considered for SO 2 designations, “2011 data must be flagged and detailed event documentati on submitted 60 days after the end of a calendar quarter in which the event occurr ed or by March 31, 2011.” Id. 64858/1-2. This proposal seems so odd that UARG suspects that it may be an error. According to Table 6 of the Proposed Rule, the detailed documentation s ubmission deadline for 2011 occurs after the deadline for 2010 documentation. See Table 6, 74 Fed. Reg. at 64858 (listing the deadline for 2010 as June 1, 2011 and the deadline for 2011 as the earlier of (i) 60 days after the end of the calendar quarter in wh ich the event occurred and (ii) March 31, 2011). March 31, 2011 is the end of the firs t calendar quarter of 2011 and will always occur before 60 days after any calendar quarter for 2011. Therefore, the Administrator’s framework fo r determining the 2011 deadline is at best arbitrary and at worst nonsensical. Finally, this deadline will not allow for consideration of a full year of data for 2011, something that would be required if any 2011 data were to be considered. See 74 Fed. Reg. at 64873/1 (defining a year as a calendar year). UARG suggests that t he deadline for detailed 2011 do cumentation submission should be March 31, 2012, or in the alternative, 60 days afte r the end of each calendar35 quarter. The deadline should be March 31 , 2013 if necessary to qualify FRMs and FEMs under new specifications. D. Issues Requiring Further Rulemaking The Proposed Rule suggests development of new screening tools, such as significant impact levels (“SIL s”), significant emissions rates (“SERs”) and significant monitoring concentrations (“SMCs”), to accompany the proposed 1-hour standard. Id. 64862/2-3. It also suggests that it may consider new PSD increments. Id. at 64861/1. 42 Furthermore, it suggests the need for anti-backslid ing provisions if either the annual or 24-hour NAAQS is repealed. Id. at 64863/3. The Proposed Rule does not provide sufficient details to provide for meaningful p ublic comment on these issues. As a result, the Proposed Rule does not pr ovide adequate notice of the Administrator’s plans for these regulations. Thus, if the Administrator intends to specify new requirements in these areas, she must conduct separate notice-and-comment ru lemaking before doing so, allowing adequate opportunity for inte rested parties to develop and provide thoughtful comments. V. Conclusion In summary, the scientific record and EPA’s own modeling of the risks associated with ambient SO 2 do not justify the Agency’ s proposed 1-hour primary SO 2 NAAQS.

42 Ideally, EPA would provide the regulator y framework for a PSD program at the time that it promulgates a new NAAQS. Clearly, that is not possible in this case. Promulgating a NAAQS without the framework to implement it -- whether that framework is a PSD program or models that can be used to provide realistic estimates of ambient air quality for pur poses of SIP development -- imposes a significant burden on States and source owners. The problems associated with an inadequately developed implementation progr am are exacerbated in this case, where States have only 18 months after a nonattainment designati on to submit an approved SIP to EPA. See CAA § 191(a).36 Nor do they establish a basis for a 1-hour NAAQS of 150 ppb. Indeed, given the low risk of short-term health effects posed by SO 2 in current ambient ai r, the record simply does not show that revision of the primary SO 2 NAAQS through promulgation of any 1- hour NAAQS is appropriate. If, cont rary to UARG’s recommendations, EPA nevertheless promul gates a 1-hour SO 2 NAAQS, the Agency should revise its implementation program fo r that standard as explained in these comments.1 Attachment A Timothy H. Savage, Ph.D., Comments on Risk and Exposure Assessment to Support the Review of the SO 2 Primary National Ambient Air Q uality Standards: First Draft (Presentation on behalf of UARG to CASAC meeting of Dec. 5-6, 2007)Comments on Risk and Exposure Assessment toSupport the Review of the SO2Primary NationalAmbient Air Quality Standards: First DraftDr. Timothy H. SavagePrepared on behalf of UARG2Three Issues in Five Minutes•Decline in the Number of Monitors•Prediction of 5-Minute Max Exceedances•Roll-Up to “Just-Meet” Standards3Decline in Number of Monitors•Draft REA documents large decline in the number of 5-minute max and 1-hour average SO2monitors.4Figure 6-11: Decline in 5-Min Max Monitors5Figure 6-17: Decline in 1-Hour Average Monitors6Assessing the Effect•EPA should explore the temporal and geographic patternsin which monitors have been removed.•In particular, EPA should focus on whether non-randommonitor closure could be introducing systematic bias in theprediction of exceedances.7Prediction Using Peak-to-Mean Ratio (PMR)•EPA employs a PMR to predict 5-minute max concentrationsfrom 1-hour average concentrations.•EPA’s current PMR is based on COV.•COV is useful for summarizing dispersion of data.•It is less appropriate as a predictive method in this setting.– Traditional standard deviation of normally distributed data.8Evidence of Over-Prediction for 400 PPB Level9Predicting Exceedances•EPA should recognize that it is predicting exceedances,which is a “rare” event.•EPA should consider using more standard parametricmodels for prediction.– Logistic, exponential, and/or log-normal.•EPA should document the quality of any prediction methodusing actual 5-minute max concentrations as a benchmark.•EPA should develop confidence intervals for any predictionmethod to assess the relevance of sampling variability.10Roll-Up Approach Stretches the Bounds of Realism•Following the NO2REA, EPA conducts a roll-up of the “asis” standard to a “just-meets” standard.•EPA’s roll-up factors used in the draft SO2REA are evenlarger than those used in the NO2REA.– Median factor is 3.75.– Top 25% of factors range from 4.47 to 15.85.•Process lacks scientific credibility as it requires anunwarranted degree of extrapolation from observed data.•Statistically, it is unclear whether an entire distribution canbe credibly “rolled up” in such a manner.11Timothy H. SavageCRA International1155 Avenue of the AmericasNew York, NY 10036(212) 520-7227tsavage@crai.com1 Attachment B J. Turim, Ph.D., S. Moolgavkar, M.D., Ph.D., E. Ander son, Ph.D., A.T.S.F., Comments on EPA’s Integrated Science Assessment for Sulf ur Oxides -- Health Criteria: Summary (Dec. 3, 2007) (written presentation to CASAC meeting of Dec. 5-6, 2007)

### COMMENTS ON EPA’S INTEGRATED SCIENCE ASSESSMENT FOR SULFUR OXIDES

- HEALTH CRITERIA

SUMMARY

J. Turim, PhD S. Moolgavkar, MD, PhD E.L. Anderson, PhD, ATSF Exponent, Inc.

December 3, 20072

COMMENTS ON EPA’S INTEGRATED SCIENCE ASSESSMENT FOR

SULFUR OXIDES

- HEALTH CRITERIA

SUMMARY

This is the summary o f a report prepared by Exponent, Inc. co mment ing on EPA’s Integrated Science Assessment for Sulfur Oxides

– Heal th Cri teri a (Fi rst External Review Draft) September 2007 (ISA). The full text was filed wi th comments of the Utilit y Air Regulatory Group to EPA on November 30, 2007. The report focused on Chapters 3 and 4 of th e ISA that summarized the clinical (chamber) and epidemio lo gi cal studi es of sulfur oxi des and the ISA interpretation of the totalit y o f th e lit erature. The emphasis of the report was on new human studies that may have significant impact on the EPA Ad ministrator’s decisio n on whether to revise the primary SO 2 NAAQS.

The ISA states “there is a causal rel at io nship between peak (1 h or l ess, ty pically 5 to 15 min) exposure to SO 2 and effects on the respiratory system, based on evidence from human clinical studies. Human clinical studies provide clear and consistent evidence of a causal relat io nshi

p between peak exposures to SO 2 at levels o f 0.5 to 1.0 ppm and effects on the respiratory system , namely decrements in lung funct io n in exercising asthmatic adul ts.”

F ive papers published in 1990 or later report ing on four clinical studies are included in ISA Table 5A

- 2 th at provides results on key human healt h effects of peak exposure to SO 2 (Magnussen et al (1990), Gong et al (1995), Tunnicliffe et al (2001, 2003), and Routl edge et al (2007)). Of the five publicat io ns , only two consi der exposures in the range of 0.5 to 1.0 ppm , and their results pr ovi de littl e addi ti onal support for th e ISA’s concl usi on of a causal relat io nship between peak exposure and respiratory system effects in exercising asthmat ics

. Magnussen et al. (1990) simply confirmed previous findings th at asthmat ics are more sensit ive t han non

- asthmati cs to SO 2 concentrations of 500 ppb.3

Gong et al. (1995) found a decrease in FEV1 and an increase in SRaw with increasing SO 2 exposure. Contrary to what would be expected, these trends did not increase wit h an increasing level of exercise

. Of th e rem aining three papers, the Tunnicliffe et al. (2001) and Routledge et al. (2007) studies offer, as described in the ISA, ‘weak and inconsistent evidence’ of changes in heart rate variabilit y at SO 2 exposures to 200 ppb for one

- hour durati on. Tu nnicliffe et al. (2003) did not show any change in lung funct io n in a group of asthmatic and non

- asthmat ic subjects exposed to SO 2 at 200 ppb. Although taken together, these five clinical studies may so mewhat contribute to the weight of evidence concernin g effects on the respiratory system and peak exposure to SO 2 , they do not contribute substant ively to the information that was available to EPA previously and lend only marginal support to the ISA’s conclusio n t hat a causal relati onship exists between peak exposure to SO 2 and effects on the respiratory system of exercising adult asthmat ics

. The ISA also concluded that “there is a likely causal relationship between short

- term (generally 24

- h average) SO 2 exposure at ambient levels and respiratory healt h eff ects,

mo st ly based on the epidemio lo gical studi es.” Fift een epidemio lo gical studi es, published since 1990 and conducted in the U.S. or Canada, are cited along with o lder studies in ISA Tables 5A

- 3 and 5A

- 4 as providing results on respiratory symptoms amo n g children and

on em ergency departm ent visits and hospital admissio ns in support of this finding. While th e ISA acknowledges the numerous methodological issues in the interpretation of the human studies o f a ir pollut io n, it does not discuss the implicatio ns of these issues specifically for SO 2 . A discussio n of these issues is particularly important for SO 2 because most of the studies on which the ISA relies, even those appearing after 1990, were published before the methodological difficult ies were recogn ized. The ISA fails to discuss recent literature that has direct bearing on these issues, its review of individual studies is not sufficient ly cr it ical, and it does not recognize significant limitations. Specific issues that are not addressed adequately in t he ISA include: treatm ent of exposure measurement error, the S

- plus convergence problem, publicat io n4

bias, effects of model cho ice, and interpretation of results in light of confounding by other pollutants, notably ozone and particulates. While the IS A acknowledges that exposure measurement error could seriously bias the results of epidemio lo gical studi es of ai r pollut io n, it should recognize that the correlat io n between ambient concentration measurements and personal exposures is poorly understood. Th e reanalyses of particulate time

- series studies prompted by the S

- pl us convergence problem indicate that reanalyses of sulfur dioxide studies c oul d be generally expected to result in effect estimates that beco me smaller and confidence intervals that become wider. A consequence o f SO 2 not having been the primary exposure of interest in recent studies is that the studies did not pay parti cular attenti on to optimizing analy ti c approaches and sensit ivit y a nalyses to the SO 2 associ at io ns wit h healt h effects. An oth er consequence is the very real possibilit y o f publicat io n bias in the SO 2 lit erature appearing in the last decade. With the generally small risks est imated in air pollut io n epidemio lo gy, and the lack of bio lo gical informat io n to guide the cho ice of mod els for control of weather, temporal trends and co

- pollutants, th e strategy fo r m odel select io n fo r the analyses o f t ime

- series data is of crit ical importance. Alt hough this problem o f “mo del cho ice” is increasingly recognized in the epi demi ol ogical litera ture, m ost of th e important papers on this issue have been ignored in t he ISA.

Alt hough t he ISA admits to the uncertaint ies surrounding the interpretation of the healt h evidence from the epidemio lo gical studi es associated wi th ambient short

- term SO 2 exposu re, i

t h as neit her discussed nor treated the m appropriately . Because of the prof ound unreso lved issues , the fifteen epidemio lo gi cal studi es published since 1990 with U.S. or Canadian cohorts can not be taken to support the existence of a likely causal rel at io nship between short

- term SO 2 exposure and respiratory effects.1 Attachment C Memorandum from Edmund Crouch, Ph.D., to Utility Air Regulatory Group, Response to EPA-HQ-ORD-2006-0260-0036 (Feb. 5, 2010).Cambridge Environmental Inc 58 Charles Street Cambridge, Massachusetts 02141 617-225-0810 FAX: 617-225-0813 www.Ca mbridgeEnvironmental.com 

## MEMORANDUM

To: Utility Air Regulatory Group From: Edmund Crouch, Ph.D. Subject: Response to EPA-HQ-ORD-2006-0260-0036 Date: February 5, 2010

Purpose of this memo As you requested, I have examined docket entry EPA-HQ-ORD-2006-0260- 0036 consisting of a memorandum entitled “Quality assura nce review of individual subject data presented in Table 3- 1 of the 2008 Integrated Science Assessment (ISA) for Sulfur Oxides” from Douglas Johns and Kirsten Simmons, EPA, NCEA-RTP to the Sulf ur Oxides NAAQS Review Docket and dated October 2, 2009 (“Johns & Simmons Memo”)

. I have also examined th e material in that docket associated with that memorandum (EPA-HQ-ORD-2006-0260-0036.1 through 0036.5, “Johns & Simmons Material”), and the final RE A document EPA-HQ-OAR-2007-0352-0033 (“Final REA”). This memorandum presents my evalua tion of the cited memorandum considered as a response to our previo us technical comments. The Johns & Simmons Memo is clearly a response to the discussion of data entry errors in our technical comments (EPA-HQ-OAR-2007-0352-0031.1, Attachment 1, “Our Comments”), and represents a welcome quality c ontrol step by the EPA, albeit one that should have been undertaken at the beginning of th e process of utilizing these data . It appears that EPA has now done a relatively good job of entering the individual data for the Linn et al . studies, for those studies for which individual data are available in the previous air docket (previously A-84-25, now EPA-HQ-OAR-2004-0112, “Previous Data”). EPA data entry quality control I have examined the quality of the new EPA data entry by comparison with my own entries for sRaw only (not FEV 1 ) for Linn et al. 1983 and 1987 (the sRaw data for the1983 study were not previously available; these data were provided by Ron Wyzga at EPA-HQ-OAR-2007-0352- 0038 and 0038.1 through 0038.8, “Wyzga Data”) and find that EPA now has only minor data entry errors for sRaw for these two studies. Specifically, for Linn et al. 1983 the following discrepancies still exist:Utility Air Regulatory Group Page 2 February 5, 2010

Cambridge Environmental Inc 58 Charles Street Cambridge, Massachusetts 02141 617-225-0810 FAX: 617-225-0813 www.Ca mbridgeEnvironmental.com Subject Condition When Column Presented EPA 582 2 Pre Mean 5.76 5.75 592 3 Pre Minute 7 2.67 2.69 584 3 Post Minute 4 7.56 7.59 416 2 Post Minute 7 5.62 5.66 416 2 Post Mean 6.05 6.03 Subject: subject ID used by Linn et al . 1983. Condition: the exposure group, as recorded in Wyzga Material. When: indicates pre or post exposure and exercise. Column: column in Wyzga Material, with “Mean” being the entry handwritten above the regular entry in Minute 7 (corresponding to “Presented average” in the Johns & Simmons Material). Presented: value given on the handwritten sh eet in the Wyzga Material (at 0038.2). EPA: value entered in the Johns & Simmons Material (at 0036.1). For Linn et al. 1987 the following discrepancies still exist: Subject Day Conc. When Column Presented EPA 879 2 0.6 ppm Post Measurement 4 35.78 35.75 1051 2 0.2 ppm Pre Measurement 4 22.07 22.09 611 2 0.2 ppm Post Measurement 2 14.51 14.54 1028 1 0.4 ppm Pre Measurement 4 4.56 4.54 892 2 0.4 ppm Post Measurement 4 29.46 29.76 Subject: subject ID used by Linn et al. 1987. Day: day number of experiment as recorded in the Wyzga Material and Previous Data. Conc: exposure concentration. When: indicates pre or post exposure and exercise. Column: name of the column in the Johns & Simmons material. Presented: column is the value given on the relevant handwritten sheets in the Wyzga Material (at 0038.3 through 0038.8), or equivalently in the Previous Data (at item IV-B-5). EPA: value entered in the Johns & Simmons Material (at 0036.2). The effect of the remaining data entry errors shou ld be negligible on any correct analysis of the data (such as that I performed in Our Comments ), although it might affect the EPA’s treatment (I have not checked) because EPA cat egorizes results as being above or below thresholds (so even minor differences in values can thro w the entry into the wrong category).
The data entries in the Johns & Simmons Material at 0036.3 check out against the Previous Data, but these are mean sRaw values only. EPA has apparently not located th e individual raw data values for sRaw for this experiment (Linn et al. 1988). Presumably EPA originally had such data to produce these mean values, but copied only the mean values to the Previous Data. I have not checked the data entry in the Johns & Simmons Materi al at 0036.4, for Linn et al

. 1990 for sRaw (this file also contains indivi dual raw FEV 1 entries for Linn et al . 1988). TheUtility Air Regulatory Group Page 3 February 5, 2010

Cambridge Environmental Inc 58 Charles Street Cambridge, Massachusetts 02141 617-225-0810 FAX: 617-225-0813 www.Ca mbridgeEnvironmental.com individual raw data are recorded in the Previous Data, but the quali ty is so low that I could not reasonably hope to decipher them within time and budget constraints. Effect of the data entry errors The Johns & Simmons Memo is carefully worded: In conclusion, the results of the full quali ty assurance review of the individual subject data presented in Table 3-1 of th e ISA, along with c onsideration of newly available data from Linn et al. (1983) do not result in any changes to the conclusions presented in the IS A for sulfur oxides (EPA, 2008). The conclusions presented in the ISA are qualita tive, and indeed correction of the data entry errors does not change those qual itative conclusions. However, the draft REA (the subject of Our Comments) attempted to use these data for a quantitative assessment, as did the Final REA. The Final REA however, takes no notice of the corrections noted in the Johns & Simmons Memo, nor indeed of the additional da ta made available there (from Linn et al . 1983). Indeed, the Final REA was added to docket EPA-HQ- OAR-2007-0352 on 8/12/09, almost two months before the Johns & Simmons Memo was written (10/2/ 09). This is despite the corrections in the entries of Table 3.1 (on which the whole REA analys is was based) that we re pointed out in Our Comments, and which have been confirmed by the Johns & Simmons Memo. The data entry in the Johns & Simmons Material a llows me to correct and augment the data used for quantitative assessments in ou r technical comments. I expect to provide an updated version of those quantitative assessments in a separate en try to the docket (this work will not be funded by UARG). However, I expect no substantial ch ange in the results ob tained — the methodology we used is insensitive to the minor changes involved. Responses to other technical comments The Johns & Simmons Memo acknowledges and corre cts data entry error we pointed out in Our Comments. The Final REA (at pages 326–327) acknowle dges the possibility of such errors, but does not correct them and ignores their potential consequences. 1 Apart from this, neither the Johns & Simmons Memo nor the Final REA responds in any meaningful way to Our Comments, despite the very substantial technical errors we identified and discussed at length. Indeed, the

1 EPA indicates that the effect of some data entry errors on the percentage responding was evaluated, but apparently there was no evaluation of the effect on the estimated dose -response parameters or number of events. The statement (Final REA, page 327) that “While st aff placed more confidence in the aver age values presented rather than the calculated average of the individual measurements,” f lies in the face of centuries of experience with hand calculations, and was of course contradicted by Professor Linn, who recommended reliance on the computed averages rather than the presen ted ones when they differed (Johns & Simmons Memo, page 2).Utility Air Regulatory Group Page 4 February 5, 2010

Cambridge Environmental Inc 58 Charles Street Cambridge, Massachusetts 02141 617-225-0810 FAX: 617-225-0813 www.Ca mbridgeEnvironmental.com Final REA is unchanged from the 2 nd draft REA in all aspects upon which we commented. In summary, the Final REA maintains the multiple e rroneous approaches we pointed out including:

• Use of a response marker (exercise-corrected in crement in sRaw) that is not predictive of symptoms, • Data entry errors, • The assumption of independence of obser vations a short time apart on the same individual, • Lack of accounting for variability in human re sponses and uncertainties in measurements, • Incorrect summing to obtain the total potenti al number of effects (by using 50 ppb bin sizes for exposures). The quantitative effect of retain ing these erroneous appr oaches is that the REA overestimates the number of pulmonary function events by a factor of approximately 80 or more. Such complete lack of response is discouragi ng — ours was the only tec hnical analysis of the REA, and our scientific analysis has been completely ignored. As stated above, I expect to provide to the Docket an updated analysis (not funded by UARG); this update will:

• Prove the independence assumption is untenable (using data in the Agency’s possession), • Update the calculations in Our Comments to incorporate corrections in data entry and the Linn et al . 1983 data, • More correctly sum the total number of eff ects (again using data in the Agency’s possession).1 Attachment D Eric S. Edgerton, Comments on Proposed SO 2 Rule (Feb. 3, 2010).Comments on Proposed SO 2 Rule Prepared by Eric S. Edgerton Atmospheric Research & Analysis, Inc. Cary, NC 27513

EPA is proposing new performance requirements for the continuous FRM that are generally reasonable and likely to be achievable with current UV fluorescent (UVF ) analyzers. It is not clear to me, however, that EPA has actually demonstrated compliance with all of the proposed new performance requirements. In addition, one major concern is the proposal to lower the allowable interference e quivalent from +/- 20 ppb to +/- 5 ppb for each interferent and from 60 ppb to 20 ppb for the tota l of all interferents. The latter amounts to 20-40% of the proposed NAAQS (50-100 ppb) and provides much too much room for false positives. Not only that, but it is unclear whether or not present day analyzers are capable of limiting “total interference” to 20 ppb.

The SEARCH network has amassed a r ecord of “total interference” becaus e of the unique approach it uses to zero SO 2 analyzers. SEARCH uses a “native” zeroi ng approach, which involves scrubbing SO 2 immediately upstream of the analyzer with a sodium carbonate impregnated annular denuder. The denuder removes SO 2 and acidic gases, but allows basic and neutral gases to pass more or less quantitatively into the UVF detection cell. Ambient air is diverted through the annular denuder for 10 minutes every 2 hours and the resulting zeroes are used to continuously adjust the SO 2 baseline by linear interpolation between successive zeros. The SO 2 baseline is then subtracted from the total SO 2 measurement to arrive at the “true” SO 2 concentration.

Figure 1 contains time series of maximum daily SO 2 zeros for two urban SEARCH sites (Jefferson Street (JST), Atlanta, GA and Birmingham (BHM), AL) for CY 2008 and CY2009. Values shown are 5-minute averages and reflect the last 5 minutes of data when th e zeroing scrubber is engaged. It should be noted that instrument baselines are initially set to 0.5-1.0 ppb with scrubbed zero air and therefore the “total interference” is roughly equal to the maximum daily SO 2 zero minus 1 ppb. Inspection of Figure 1 shows several relevant features. First, the lowest zeros are on the order of 0.5-1 ppb, the scrubbed zero air setpoint. This indicates there are times with little or no interference, but also strongly suggests that the preponderance of interferences in these two cities ar e positive (i.e., increase apparent concentrations). Second, “total interferences ” for both sites exceed 10 ppb, but maximum values at JST are more than twice those at BHM (i.e., 27 ppb vs. 12.5 ppb). This is significant because Birmingham, AL has many industrial sources, including metallurgy and steelmaking that are absent or much more limited in Atlanta, GA. If daily maximum zeros were higher at BHM than JST, we might ascribe such to unique industrial sources. Since this is not the case, we infer this level of interference to be wide spread among urban sites. Third,there is a strong seasonality in the zeros and this is much more apparent at JST than BHM. Highest zeros occur in the coldest months and lowest zeros in the warmest months. Maximum daily zeroes above 5 ppb are rare at JST from April through September, bu t much more common at BHM during the same time period. Given that these are intermit tent estimates of interference (i.e., every two hours) it is almost certain that that actual interferences were even higher than those shown in Figure 1.

The above results show that “total interference” in SO 2 measurements, using late model continuous analyzers, can be a serious issue and can potentially lead to false positive exceedances of the proposed NAAQS. It then becomes incumbent upon EPA to demo nstrate that FRM and FEM SO 2 analyzers have the capability to minimize interferences, not only in a laborator y setting, but on a continuing basis in the field.Figure 1. Maximum daily SO 2 zeros (5-minute average) for JST (upper) and BHM (lower), 2008-9.

JST Max SO2 Zero

0 5 10 15 20 25 301/1/082/1/083/1/084/1/085/1/086/1/087/1/088/1/089/1/0810/1/0811/1/0812/1/081/1/092/1/093/1/094/1/095/1/096/1/097/1/098/1/099/1/0910/1/0911/1/0912/1/09

BHM Max SO2 Zero

0.0 2.5 5.0 7.5 10.0 12.5 15.01/1/082/1/083/1/084/1/085/1/086/1/087/1/088/1/089/1/0810/1/0811/1/0812/1/081/1/092/1/093/1/094/1/095/1/096/1/097/1/098/1/099/1/0910/1/0911/1/0912/1/09